On 05/02/2022 17:55, Max Demian wrote:
> I once had a 78
> RPM record deck which had a heavy horseshoe magnet with a coil between
> the pole pieces and a moving iron holding the (use once) needle.

Mine is exactly like that.

Luckily, I found (and bought) in an antiques fair a "Wartime Economy
Gramophone Needle Sharpener" so that I can use a needle dozens of times
until it is too short to use again.

On 05/02/2022 18:50, Pamela wrote:
> On 16:35 5 Feb 2022, Indy Jess John said:
>
>> On 05/02/2022 01:32, Pamela wrote:
>>> On 16:05 2 Feb 2022, David Paste said:
>>>
>>>> Hello all,
>>>>
>>>> I return with yet more aerial related questions.
>>>>
>>>> The radio next to me has an AM radio with reception from 522 kHz to
>>>> 1629 kHz, giving approximate wavelengths of 574 metres to 184
>>>> metres. I understand that AM radio is vertically polarised in the
>>>> UK. A quarter wave dipole would be a bit unwieldy at those
>>>> wavelengths, so loop antennas are used.
>>>>
>>>> 1. How long should the wire that is looped be?
>>>>
>>>> 1(a). Can connecting the AM aerial terminal to the central heating
>>>> copper piping act as an aerial? I am discouraged from just trying
>>>> this in case there's something I am not aware of which results in a
>>>> release of the Magic Smoke.
>>>
>>> I have a 1940s valve radio which needs an external aerial like
>>> yours. I haven't used it in ages but we would use a long wire.
>>> Positioning a loop every time you tune a station would be too
>>> fiddly. Using an earth would be posh.
>>>
>>> The last time I tried it the creaky old thing was working well. It's
>>> almost identical to this one on eBay, although not as glossy and
>>> perfect. Mine has a wooden case and I love it to bits. Visitors
>>> think it's some broken old radio kept as an ornament but actually
>>> it's kept because it works.
>>>
>>> https://www.ebay.co.uk/itm/224819633440
>>
>> I have an old radiogram which has a 78s only deck so perhaps 1940s or
>> early 1950s. When I got it the radio motor-boated until I tapped each
>> valve and found that the rectifier being tapped sometimes brought the
>> radio into working order, and a replacement rectifier valve was all
>> it needed.
>>
>> I ran a wire from the aerial socket out of the window, and connected
>> it to the washing line that had a steel core and ran down the garden,
>> and the radio reception was excellent with that arrangement.
>>
>> Jim
>
> A radiogram is a big snazzy step upwards compared to a plain radio. Only
> for the well off.
>
With a bit of haggling having extracted the admission that it didn't
work properly, I got it surprisingly cheaply.

I also did a trade with someone else: a used but in good working order
rectifier valve in exchange for a silencer for a wartime ex-army Douglas
generator set which required exactly the same silencer as the early fire
pumps. That pump engine was subsequently modified into the power unit
for the Hillman Imp, and I had a spare Imp silencer. :-)

Jim

In article <XnsAE35BFBB96C037B93@144.76.35.252>,
Pamela <pamela.private.mailbox@gmail.com> wrote:
> On 16:35 5 Feb 2022, Indy Jess John said:

> > On 05/02/2022 01:32, Pamela wrote:
> >> On 16:05 2 Feb 2022, David Paste said:
> >>
> >>> Hello all,
> >>>
> >>> I return with yet more aerial related questions.
> >>>
> >>> The radio next to me has an AM radio with reception from 522 kHz to
> >>> 1629 kHz, giving approximate wavelengths of 574 metres to 184
> >>> metres. I understand that AM radio is vertically polarised in the
> >>> UK. A quarter wave dipole would be a bit unwieldy at those
> >>> wavelengths, so loop antennas are used.
> >>>
> >>> 1. How long should the wire that is looped be?
> >>>
> >>> 1(a). Can connecting the AM aerial terminal to the central heating
> >>> copper piping act as an aerial? I am discouraged from just trying
> >>> this in case there's something I am not aware of which results in a
> >>> release of the Magic Smoke.
> >>
> >> I have a 1940s valve radio which needs an external aerial like
> >> yours. I haven't used it in ages but we would use a long wire.
> >> Positioning a loop every time you tune a station would be too
> >> fiddly. Using an earth would be posh.
> >>
> >> The last time I tried it the creaky old thing was working well. It's
> >> almost identical to this one on eBay, although not as glossy and
> >> perfect. Mine has a wooden case and I love it to bits. Visitors
> >> think it's some broken old radio kept as an ornament but actually
> >> it's kept because it works.
> >>
> >> https://www.ebay.co.uk/itm/224819633440
> >
> > I have an old radiogram which has a 78s only deck so perhaps 1940s or
> > early 1950s. When I got it the radio motor-boated until I tapped each
> > valve and found that the rectifier being tapped sometimes brought the
> > radio into working order, and a replacement rectifier valve was all
> > it needed.
> >
> > I ran a wire from the aerial socket out of the window, and connected
> > it to the washing line that had a steel core and ran down the garden,
> > and the radio reception was excellent with that arrangement.
> >
> > Jim

> A radiogram is a big snazzy step upwards compared to a plain radio. Only
> for the well off.

Oh no. Just after hire purchase came in, I was in an e3ectrical shop in
Edinburgh and I overheard a mother and daughter. "Look at that radiogram,
it's only a pound deposit - we could give it and the payment book to Dad
for Christmas."

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 05/02/2022 18:50, Pamela wrote:
> A radiogram is a big snazzy step upwards compared to a plain radio. Only
> for the well off.

BBC;s Repair Shop get quite a few on for repair, there was one last
week. They found an identical on and swapped the radio part over and
got a record deck.

When they do repair them, the first thing the expert does is check all
the capacitors.

On 20:38 5 Feb 2022, Indy Jess John said:

> On 05/02/2022 18:50, Pamela wrote:
>> On 16:35 5 Feb 2022, Indy Jess John said:
>>
>>> On 05/02/2022 01:32, Pamela wrote:
>>>> On 16:05 2 Feb 2022, David Paste said:
>>>>
>>>>> Hello all,
>>>>>
>>>>> I return with yet more aerial related questions.
>>>>>
>>>>> The radio next to me has an AM radio with reception from 522 kHz
>>>>> to 1629 kHz, giving approximate wavelengths of 574 metres to 184
>>>>> metres. I understand that AM radio is vertically polarised in the
>>>>> UK. A quarter wave dipole would be a bit unwieldy at those
>>>>> wavelengths, so loop antennas are used.
>>>>>
>>>>> 1. How long should the wire that is looped be?
>>>>>
>>>>> 1(a). Can connecting the AM aerial terminal to the central
>>>>> heating copper piping act as an aerial? I am discouraged from
>>>>> just trying this in case there's something I am not aware of
>>>>> which results in a release of the Magic Smoke.
>>>>
>>>> I have a 1940s valve radio which needs an external aerial like
>>>> yours. I haven't used it in ages but we would use a long wire.
>>>> Positioning a loop every time you tune a station would be too
>>>> fiddly. Using an earth would be posh.
>>>>
>>>> The last time I tried it the creaky old thing was working well.
>>>> It's almost identical to this one on eBay, although not as glossy
>>>> and perfect. Mine has a wooden case and I love it to bits.
>>>> Visitors think it's some broken old radio kept as an ornament but
>>>> actually it's kept because it works.
>>>>
>>>> https://www.ebay.co.uk/itm/224819633440
>>>
>>> I have an old radiogram which has a 78s only deck so perhaps 1940s
>>> or early 1950s. When I got it the radio motor-boated until I tapped
>>> each valve and found that the rectifier being tapped sometimes
>>> brought the radio into working order, and a replacement rectifier
>>> valve was all it needed.
>>>
>>> I ran a wire from the aerial socket out of the window, and
>>> connected it to the washing line that had a steel core and ran down
>>> the garden, and the radio reception was excellent with that
>>> arrangement.
>>>
>>> Jim
>>
>> A radiogram is a big snazzy step upwards compared to a plain radio.
>> Only for the well off.
>>
> With a bit of haggling having extracted the admission that it didn't
> work properly, I got it surprisingly cheaply.
>
> I also did a trade with someone else: a used but in good working
> order rectifier valve in exchange for a silencer for a wartime
> ex-army Douglas generator set which required exactly the same
> silencer as the early fire pumps. That pump engine was subsequently
> modified into the power unit for the Hillman Imp, and I had a spare
> Imp silencer. :-)
>
> Jim

That's starting to sound like one of those competitions where someone
starts with a pencil and aims to keep trading it until they have a
house!

On 20:36 5 Feb 2022, charles said:

> In article <XnsAE35BFBB96C037B93@144.76.35.252>,
> Pamela <pamela.private.mailbox@gmail.com> wrote:
>> On 16:35 5 Feb 2022, Indy Jess John said:
>
>> > On 05/02/2022 01:32, Pamela wrote:
>> >> On 16:05 2 Feb 2022, David Paste said:
>> >>
>> >>> Hello all,
>> >>>
>> >>> I return with yet more aerial related questions.
>> >>>
>> >>> The radio next to me has an AM radio with reception from 522 kHz
>> >>> to 1629 kHz, giving approximate wavelengths of 574 metres to 184
>> >>> metres. I understand that AM radio is vertically polarised in
>> >>> the UK. A quarter wave dipole would be a bit unwieldy at those
>> >>> wavelengths, so loop antennas are used.
>> >>>
>> >>> 1. How long should the wire that is looped be?
>> >>>
>> >>> 1(a). Can connecting the AM aerial terminal to the central
>> >>> heating copper piping act as an aerial? I am discouraged from
>> >>> just trying this in case there's something I am not aware of
>> >>> which results in a release of the Magic Smoke.
>> >>
>> >> I have a 1940s valve radio which needs an external aerial like
>> >> yours. I haven't used it in ages but we would use a long wire.
>> >> Positioning a loop every time you tune a station would be too
>> >> fiddly. Using an earth would be posh.
>> >>
>> >> The last time I tried it the creaky old thing was working well.
>> >> It's almost identical to this one on eBay, although not as glossy
>> >> and perfect. Mine has a wooden case and I love it to bits.
>> >> Visitors think it's some broken old radio kept as an ornament but
>> >> actually it's kept because it works.
>> >>
>> >> https://www.ebay.co.uk/itm/224819633440
>> >
>> > I have an old radiogram which has a 78s only deck so perhaps 1940s
>> > or early 1950s. When I got it the radio motor-boated until I
>> > tapped each valve and found that the rectifier being tapped
>> > sometimes brought the radio into working order, and a replacement
>> > rectifier valve was all it needed.
>> >
>> > I ran a wire from the aerial socket out of the window, and
>> > connected it to the washing line that had a steel core and ran
>> > down the garden, and the radio reception was excellent with that
>> > arrangement.
>> >
>> > Jim
>
>> A radiogram is a big snazzy step upwards compared to a plain radio.
>> Only for the well off.
>
> Oh no. Just after hire purchase came in, I was in an e3ectrical shop
> in Edinburgh and I overheard a mother and daughter. "Look at that
> radiogram, it's only a pound deposit - we could give it and the
> payment book to Dad for Christmas."

So brilliant!

A friend used to run a car dealership and customers who were buying on
credit finance would only ask what the monthly payments were and for
how long but never ask about the total cost.

"Pamela" <pamela.private.mailbox@gmail.com> wrote in message
news:XnsAE35E223869B737B93@144.76.35.252...

>> Oh no. Just after hire purchase came in, I was in an e3ectrical shop
>> in Edinburgh and I overheard a mother and daughter. "Look at that
>> radiogram, it's only a pound deposit - we could give it and the
>> payment book to Dad for Christmas."
>
> So brilliant!
>
> A friend used to run a car dealership and customers who were buying on
> credit finance would only ask what the monthly payments were and for
> how long but never ask about the total cost.

Back in the days before any credit arrangement had to quote the total cost -
ie monthly cost x number of payment before you'd paid off the loan. One of
the things which is better nowadays than it used to be.

I fell foul of a company which had a hidden cost that did not materialise
until after I'd signed up, even though I'd asked "how many payments of £x
will I need to make - what is the total that I'll need to pay". As soon as I
got the paperwork and noticed the hidden charge, I cancelled immediately (*)
because the deal what I had been led to believe that it would be: a clear
case of mis-selling. This was before the days when companies had to state
up-front, but I *had* taken the precaution of asking - and I was lied to. I
should have reported it to trading standards in case anyone else got caught
out.

(*) I'd been led to believe that it was interest-free credit and therefore I
was not paying any extra for credit. After I found that I would pay extra, I
opted instead to pay the normal purchase price up-front (I could afford it,
but I wasn't going to turn down *interest free* credit).

On 05/02/2022 22:08, Pamela wrote:
> On 20:38 5 Feb 2022, Indy Jess John said:
>
>> On 05/02/2022 18:50, Pamela wrote:
>>> On 16:35 5 Feb 2022, Indy Jess John said:
>>>
>>>> On 05/02/2022 01:32, Pamela wrote:
>>>>> On 16:05 2 Feb 2022, David Paste said:
>>>>>
>>>>>> Hello all,
>>>>>>
>>>>>> I return with yet more aerial related questions.
>>>>>>
>>>>>> The radio next to me has an AM radio with reception from 522 kHz
>>>>>> to 1629 kHz, giving approximate wavelengths of 574 metres to 184
>>>>>> metres. I understand that AM radio is vertically polarised in the
>>>>>> UK. A quarter wave dipole would be a bit unwieldy at those
>>>>>> wavelengths, so loop antennas are used.
>>>>>>
>>>>>> 1. How long should the wire that is looped be?
>>>>>>
>>>>>> 1(a). Can connecting the AM aerial terminal to the central
>>>>>> heating copper piping act as an aerial? I am discouraged from
>>>>>> just trying this in case there's something I am not aware of
>>>>>> which results in a release of the Magic Smoke.
>>>>>
>>>>> I have a 1940s valve radio which needs an external aerial like
>>>>> yours. I haven't used it in ages but we would use a long wire.
>>>>> Positioning a loop every time you tune a station would be too
>>>>> fiddly. Using an earth would be posh.
>>>>>
>>>>> The last time I tried it the creaky old thing was working well.
>>>>> It's almost identical to this one on eBay, although not as glossy
>>>>> and perfect. Mine has a wooden case and I love it to bits.
>>>>> Visitors think it's some broken old radio kept as an ornament but
>>>>> actually it's kept because it works.
>>>>>
>>>>> https://www.ebay.co.uk/itm/224819633440
>>>>
>>>> I have an old radiogram which has a 78s only deck so perhaps 1940s
>>>> or early 1950s. When I got it the radio motor-boated until I tapped
>>>> each valve and found that the rectifier being tapped sometimes
>>>> brought the radio into working order, and a replacement rectifier
>>>> valve was all it needed.
>>>>
>>>> I ran a wire from the aerial socket out of the window, and
>>>> connected it to the washing line that had a steel core and ran down
>>>> the garden, and the radio reception was excellent with that
>>>> arrangement.
>>>>
>>>> Jim
>>>
>>> A radiogram is a big snazzy step upwards compared to a plain radio.
>>> Only for the well off.
>>>
>> With a bit of haggling having extracted the admission that it didn't
>> work properly, I got it surprisingly cheaply.
>>
>> I also did a trade with someone else: a used but in good working
>> order rectifier valve in exchange for a silencer for a wartime
>> ex-army Douglas generator set which required exactly the same
>> silencer as the early fire pumps. That pump engine was subsequently
>> modified into the power unit for the Hillman Imp, and I had a spare
>> Imp silencer. :-)
>>
>> Jim
>
> That's starting to sound like one of those competitions where someone
> starts with a pencil and aims to keep trading it until they have a
> house!

I have got a pencil. How do you propose to improve my starting position?
:-)

Jim

Ian Jackson wrote:

> In message <XnsAE357F6DD7A7A37B93@144.76.35.252>, Pamela
> <pamela.private.mailbox@gmail.com> writes
> > On 08:48 5 Feb 2022, Ian Jackson said:
> >
> > > In message <XnsAE35FBC3B84937B93@144.76.35.252>, Pamela
> >><pamela.private.mailbox@gmail.com> writes
> > > > On 16:05 2 Feb 2022, David Paste said:
> > > >
> > > > > Hello all,
> > > > >
> > > > > I return with yet more aerial related questions.
> > > > >
> > > > > The radio next to me has an AM radio with reception from 522
> > > > > kHz to 1629 kHz, giving approximate wavelengths of 574 metres
> > > > > to 184 metres. I understand that AM radio is vertically
> > > > > polarised in the UK. A quarter wave dipole would be a bit
> > > > > unwieldy at those wavelengths, so loop antennas are used.
> > > > >
> > > > > 1. How long should the wire that is looped be?
> > > > >
> > > > > 1(a). Can connecting the AM aerial terminal to the central
> > > > > heating copper piping act as an aerial? I am discouraged from
> > > > > just trying this in case there's something I am not aware of
> > > > > which results in a release of the Magic Smoke.
> > > >
> > > > I have a 1940s valve radio which needs an external aerial like
> > > > yours. I haven't used it in ages but we would use a long wire.
> > > > Positioning a loop every time you tune a station would be too
> > > > fiddly. Using an earth would be posh.
> > > >
> > > > The last time I tried it the creaky old thing was working well.
> > > > It's almost identical to this one on eBay, although not as
> > > > glossy and perfect. Mine has a wooden case and I love it to
> > > > bits. Visitors think it's some broken old radio kept as an
> > > > ornament but actually it's kept because it works.
> > > >
> > > > https://www.ebay.co.uk/itm/224819633440
> > >
> > > Before ferrite rods, some radios did have internal loop aerials
> > > inside the wooden case (usually with additional connections for an
> > > external aerial and earth). Obviously the loop was directional,
> > > but unless the required station was exactly in one of the two
> > > broadside nulls, the orientation of the radio was probably not
> > > that critical for normal domestic use.
> > >
> > > Regarding using old radios and record players, I'm rather bemused
> > > when someone brings one into The Repair Shop (on TV) for
> > > restoration. So far I've never seen any repairer take the
> > > precaution of at least doing a slow, controlled wind-up of the
> > > mains voltage to give the electrolytic capacitors a chance to
> > > reform, and to minimise the chances of other catastrophic
> > > failures.
> >
> > I haven't used the radio for about 5 years, when it worked fine.
> > What precautions should I follow to keep it going?
> >
> > I've never heard of reforming capacitors. How do you do a "slow,
> > controlled wind-up of the mains voltage" or anything else that's
> > needed? I couldn't find any decent web pages offering advice.
>
> Start here:
> https://tinyurl.com/2p8kdad6
> >
> > I was given the radio second-hand by the local TV shop which was
> > throwing it out 50 years ago and it would be nice to keep it going.
> >
> > All the components are original (I once changed the speaker cloth!)
> > but I don't have the stamina or equipment to get into a restoration
> > project swapping lots of new components for old. However if doing
> > something pays dividends then I would have to do it.
>
> Old electronic components are prone to changing their values over
> time. Capacitors generally go leaky. The leaky high-voltage
> electrolytics can short out the HT supply (often around 200V or
> more), and something's going to go bang or burn out (could be
> something irreplaceable, like the mains transformer). Although
> usually not electrolytic, leaky coupling capacitors (between anode
> and grid) will cause a valve to take excessive current.
>
> Ideally you should check all potentially faulty components before
> applying the normal mains, but the minimum work might be at least to
> gradually wind up the supply voltage. If you don't have the
> facilities, try inserting a filament mains light bulb in series with
> the mains (maybe starting with a low wattage one (which will have the
> highest resistance), and then progressing to higher wattages.
>
> Of course, if there's a valve rectifier (and not solid-state), leaky
> HT electrolytics won't get any voltage across them until there's
> sufficient mains voltage to get the rectifier heaters glowing - so
> it's all a bit of a compromise.
>
> With any old electronic equipment that's working, it's probably a
> good idea to power it up every so often to help stop the capacitors
> going leaky.

A good YouTube channel for watching electronic restoration is the
Canadian channel: https://www.youtube.com/c/MrCarlsonsLab .

He always powers old equipment slowly, with a filament bulb in series
with the mains.

--

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williamwright wrote:

> On 05/02/2022 08:48, Ian Jackson wrote:
> > Before ferrite rods, some radios did have internal loop aerials
> > inside the wooden case (usually with additional connections for an
> > external aerial and earth). Obviously the loop was directional,
> > but unless the required station was exactly in one of the two
> > broadside nulls, the orientation of the radio was probably not
> > that critical for normal domestic use.
>
> These little plastic frames wound with about six turns of thin wire
> are still supplied with some tuners and audio units.
>
> Bill

www.snglinks.com/pub/pics/loop.jpg

--

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Yes there are many still around in fact. they are not very efficient power
wise of course since valves need heaters to create the free electrons that
can move between plates.
In my view the oscillators based on Valves are cleaner and quieter than any
semiconductor one is. Reason not known, and this seems to result in much
lower noise on receive in most superhet designs.
Be aware though that out there in the second hand market are some nasty
examples of ac/ DC radios which do not use a mains transformer with isolated
windings, but use a dropper resistor with taps instead.
This results in a lot of heat and the chassis being live. The aerial
terminal on these is often isolated by a simple capacitor, but the earth is
not, so don't to earth it!
Some sets were retro fitted with droppers which is why I am warning people.
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Ian Jackson" <ianREMOVETHISjackson@g3ohx.co.uk> wrote in message
news:zku7smDCmo$hFwDQ@brattleho.plus.com...
> In message <XnsAE357F6DD7A7A37B93@144.76.35.252>, Pamela
> <pamela.private.mailbox@gmail.com> writes
>>On 08:48 5 Feb 2022, Ian Jackson said:
>>
>>> In message <XnsAE35FBC3B84937B93@144.76.35.252>, Pamela
>>> <pamela.private.mailbox@gmail.com> writes
>>>>On 16:05 2 Feb 2022, David Paste said:
>>>>
>>>>> Hello all,
>>>>>
>>>>> I return with yet more aerial related questions.
>>>>>
>>>>> The radio next to me has an AM radio with reception from 522 kHz to
>>>>> 1629 kHz, giving approximate wavelengths of 574 metres to 184
>>>>> metres. I understand that AM radio is vertically polarised in the
>>>>> UK. A quarter wave dipole would be a bit unwieldy at those
>>>>> wavelengths, so loop antennas are used.
>>>>>
>>>>> 1. How long should the wire that is looped be?
>>>>>
>>>>> 1(a). Can connecting the AM aerial terminal to the central heating
>>>>> copper piping act as an aerial? I am discouraged from just trying
>>>>> this in case there's something I am not aware of which results in a
>>>>> release of the Magic Smoke.
>>>>
>>>>I have a 1940s valve radio which needs an external aerial like yours.
>>>>I haven't used it in ages but we would use a long wire. Positioning a
>>>>loop every time you tune a station would be too fiddly. Using an
>>>>earth would be posh.
>>>>
>>>>The last time I tried it the creaky old thing was working well. It's
>>>>almost identical to this one on eBay, although not as glossy and
>>>>perfect. Mine has a wooden case and I love it to bits. Visitors
>>>>think it's some broken old radio kept as an ornament but actually
>>>>it's kept because it works.
>>>>
>>>>https://www.ebay.co.uk/itm/224819633440
>>>
>>> Before ferrite rods, some radios did have internal loop aerials
>>> inside the wooden case (usually with additional connections for an
>>> external aerial and earth). Obviously the loop was directional, but
>>> unless the required station was exactly in one of the two broadside
>>> nulls, the orientation of the radio was probably not that critical
>>> for normal domestic use.
>>>
>>> Regarding using old radios and record players, I'm rather bemused
>>> when someone brings one into The Repair Shop (on TV) for restoration.
>>> So far I've never seen any repairer take the precaution of at least
>>> doing a slow, controlled wind-up of the mains voltage to give the
>>> electrolytic capacitors a chance to reform, and to minimise the
>>> chances of other catastrophic failures.
>>
>>I haven't used the radio for about 5 years, when it worked fine. What
>>precautions should I follow to keep it going?
>>
>>I've never heard of reforming capacitors. How do you do a "slow,
>>controlled wind-up of the mains voltage" or anything else that's needed? I
>>couldn't find any decent web pages offering advice.
>
> Start here:
> https://tinyurl.com/2p8kdad6
>>
>>I was given the radio second-hand by the local TV shop which was throwing
>>it out 50 years ago and it would be nice to keep it going.
>>
>>All the components are original (I once changed the speaker cloth!) but I
>>don't have the stamina or equipment to get into a restoration project
>>swapping lots of new components for old. However if doing something pays
>>dividends then I would have to do it.
>
> Old electronic components are prone to changing their values over time.
> Capacitors generally go leaky. The leaky high-voltage electrolytics can
> short out the HT supply (often around 200V or more), and something's going
> to go bang or burn out (could be something irreplaceable, like the mains
> transformer). Although usually not electrolytic, leaky coupling capacitors
> (between anode and grid) will cause a valve to take excessive current.
>
> Ideally you should check all potentially faulty components before applying
> the normal mains, but the minimum work might be at least to gradually wind
> up the supply voltage. If you don't have the facilities, try inserting a
> filament mains light bulb in series with the mains (maybe starting with a
> low wattage one (which will have the highest resistance), and then
> progressing to higher wattages.
>
> Of course, if there's a valve rectifier (and not solid-state), leaky HT
> electrolytics won't get any voltage across them until there's sufficient
> mains voltage to get the rectifier heaters glowing - so it's all a bit of
> a compromise.
>
> With any old electronic equipment that's working, it's probably a good
> idea to power it up every so often to help stop the capacitors going
> leaky.
> --
> Ian

In article <X8qdnfJFSvlGLmP8nZ2dnUU7-WfNnZ2d@brightview.co.uk>, Max
Demian
<max_demian@bigfoot.com> wrote:
> On 05/02/2022 16:51, williamwright wrote:
> > On 05/02/2022 08:48, Ian Jackson wrote:

> >> Before ferrite rods, some radios did have internal loop aerials
> >> inside the wooden case (usually with additional connections for an
> >> external aerial and earth). Obviously the loop was directional, but
> >> unless the required station was exactly in one of the two broadside
> >> nulls, the orientation of the radio was probably not that critical
> >> for normal domestic use.
> >
> > These little plastic frames wound with about six turns of thin wire
> > are still supplied with some tuners and audio units.

> Are they as good as ferrite rod aerials?

The advantage of a loop is it that it is less prone to saturation - i.e.
less likely to be affected by some kinds of interference - than a ferrite
rod. The snag is that a small plain loop won't grab as much RF signal
power. But given the sensitivity and low noise of modern transistor devices
that may not matter much.

> My Armstrong 626 had a ferrite aerial at the back cased in plastic which
> could be turned if there was space.

Mine still has one. :-)) I tend to only use the FM though.

FWIW IIRC In that example the ferrite rod isn't made resonant, so gave
lower gain than most portable ferrite rods. But again, quite sufficient
given solid state devices to follow it.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article <sto6qu$qmo$1@dont-email.me>, Brian Gaff \(Sofa\)
<briang1@blueyonder.co.uk> wrote:
> Yes there are many still around in fact. they are not very efficient
> power wise of course since valves need heaters to create the free
> electrons that can move between plates. In my view the oscillators based
> on Valves are cleaner and quieter than any semiconductor one is. Reason
> not known, and this seems to result in much lower noise on receive in
> most superhet designs. Be aware though that out there in the second hand
> market are some nasty examples of ac/ DC radios which do not use a mains
> transformer with isolated windings, but use a dropper resistor with taps
> instead. This results in a lot of heat and the chassis being live. The
> aerial terminal on these is often isolated by a simple capacitor, but the
> earth is not, so don't to earth it! Some sets were retro fitted with
> droppers which is why I am warning people.

> Brian

And, we must not forget "line cord" where the mains lead was also a voltage
dropper.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

In article <j67t14Fici4U1@mid.individual.net>, williamwright
<wrightsaerials@f2s.com> wrote:
> On 05/02/2022 16:19, David Woolley wrote:
> > On 05/02/2022 16:07, David Paste wrote:
> >> Wide angle lens in photography terms?
> >
> > Not a valid analogy.

> The human brain is like a giant fish. It had gills through which it can
> breathe.

Sounds fishy to me...

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 14:28 5 Feb 2022, Ian Jackson said:

> In message <XnsAE357F6DD7A7A37B93@144.76.35.252>, Pamela
> <pamela.private.mailbox@gmail.com> writes
>>On 08:48 5 Feb 2022, Ian Jackson said:
>>
>>> In message <XnsAE35FBC3B84937B93@144.76.35.252>, Pamela
>>> <pamela.private.mailbox@gmail.com> writes
>>>>On 16:05 2 Feb 2022, David Paste said:
>>>>
>>>>> Hello all,
>>>>>
>>>>> I return with yet more aerial related questions.
>>>>>
>>>>> The radio next to me has an AM radio with reception from 522 kHz
>>>>> to 1629 kHz, giving approximate wavelengths of 574 metres to 184
>>>>> metres. I understand that AM radio is vertically polarised in the
>>>>> UK. A quarter wave dipole would be a bit unwieldy at those
>>>>> wavelengths, so loop antennas are used.
>>>>>
>>>>> 1. How long should the wire that is looped be?
>>>>>
>>>>> 1(a). Can connecting the AM aerial terminal to the central
>>>>> heating copper piping act as an aerial? I am discouraged from
>>>>> just trying this in case there's something I am not aware of
>>>>> which results in a release of the Magic Smoke.
>>>>
>>>>I have a 1940s valve radio which needs an external aerial like
>>>>yours. I haven't used it in ages but we would use a long wire.
>>>>Positioning a loop every time you tune a station would be too
>>>>fiddly. Using an earth would be posh.
>>>>
>>>>The last time I tried it the creaky old thing was working well.
>>>>It's almost identical to this one on eBay, although not as glossy
>>>>and perfect. Mine has a wooden case and I love it to bits.
>>>>Visitors think it's some broken old radio kept as an ornament but
>>>>actually it's kept because it works.
>>>>
>>>>https://www.ebay.co.uk/itm/224819633440
>>>
>>> Before ferrite rods, some radios did have internal loop aerials
>>> inside the wooden case (usually with additional connections for an
>>> external aerial and earth). Obviously the loop was directional, but
>>> unless the required station was exactly in one of the two broadside
>>> nulls, the orientation of the radio was probably not that critical
>>> for normal domestic use.
>>>
>>> Regarding using old radios and record players, I'm rather bemused
>>> when someone brings one into The Repair Shop (on TV) for
>>> restoration. So far I've never seen any repairer take the
>>> precaution of at least doing a slow, controlled wind-up of the
>>> mains voltage to give the electrolytic capacitors a chance to
>>> reform, and to minimise the chances of other catastrophic failures.
>>
>>I haven't used the radio for about 5 years, when it worked fine. What
>>precautions should I follow to keep it going?
>>
>>I've never heard of reforming capacitors. How do you do a "slow,
>>controlled wind-up of the mains voltage" or anything else that's
>>needed? I couldn't find any decent web pages offering advice.
>
> Start here:
> https://tinyurl.com/2p8kdad6
>>
>>I was given the radio second-hand by the local TV shop which was
>>throwing it out 50 years ago and it would be nice to keep it going.
>>
>>All the components are original (I once changed the speaker cloth!)
>>but I don't have the stamina or equipment to get into a restoration
>>project swapping lots of new components for old. However if doing
>>something pays dividends then I would have to do it.
>
> Old electronic components are prone to changing their values over
> time. Capacitors generally go leaky. The leaky high-voltage
> electrolytics can short out the HT supply (often around 200V or
> more), and something's going to go bang or burn out (could be
> something irreplaceable, like the mains transformer). Although
> usually not electrolytic, leaky coupling capacitors (between anode
> and grid) will cause a valve to take excessive current.
>
> Ideally you should check all potentially faulty components before
> applying the normal mains, but the minimum work might be at least to
> gradually wind up the supply voltage. If you don't have the
> facilities, try inserting a filament mains light bulb in series with
> the mains (maybe starting with a low wattage one (which will have the
> highest resistance), and then progressing to higher wattages.
>
> Of course, if there's a valve rectifier (and not solid-state), leaky
> HT electrolytics won't get any voltage across them until there's
> sufficient mains voltage to get the rectifier heaters glowing - so
> it's all a bit of a compromise.
>
> With any old electronic equipment that's working, it's probably a
> good idea to power it up every so often to help stop the capacitors
> going leaky.

Thanks for the info. Out of interest, where in life's journey have you
gained such knowledge about these things? I imagine any professional
work on equivalent modern equipment never needs such methods.

On 06/02/2022 10:48, charles wrote:
> In article <sto6qu$qmo$1@dont-email.me>, Brian Gaff \(Sofa\)
> <briang1@blueyonder.co.uk> wrote:

>> Yes there are many still around in fact. they are not very efficient
>> power wise of course since valves need heaters to create the free
>> electrons that can move between plates. In my view the oscillators based
>> on Valves are cleaner and quieter than any semiconductor one is. Reason
>> not known, and this seems to result in much lower noise on receive in
>> most superhet designs. Be aware though that out there in the second hand
>> market are some nasty examples of ac/ DC radios which do not use a mains
>> transformer with isolated windings, but use a dropper resistor with taps
>> instead. This results in a lot of heat and the chassis being live. The
>> aerial terminal on these is often isolated by a simple capacitor, but the
>> earth is not, so don't to earth it! Some sets were retro fitted with
>> droppers which is why I am warning people.

> And, we must not forget "line cord" where the mains lead was also a voltage
> dropper.

I had a radio where the resistive line cord had evidently failed and
been replaced with a dropper resistor inside the cabinet. It generated
so much heat that the tuning drifted after switch on. It was a large
portable which worked on 100V, 220V, 240V AC/DC mains or battery. It
used the usual D series valves for battery plus some extra mains valves
when working from the mains.

--
Max Demian

On 06/02/2022 14:48, Pamela wrote:
> Thanks for the info. Out of interest, where in life's journey have you
> gained such knowledge about these things? I imagine any professional
> work on equivalent modern equipment never needs such methods.

I thought the problem of electrolytic capacitors losing their oxide
layer with non-use was actually fairly well known.

Electrolytics get their high capacitance by having a very thin oxide
insulation layer, obtained by basically a corrosion process. In normal
use they can get away with defects appearing in this layer, because the
metal re-oxidises and recreates the insulation, but if they are left for
a long time, the oxide layer can dissolve away, such that the current
needed to regrow it is too great, and something overheats and lets the
magic smoke out.

On 05/02/2022 18:10, Jim Lesurf wrote:
> The snag is that a small plain loop won't grab as much RF signal
> power. But given the sensitivity and low noise of modern transistor devices
> that may not matter much.

In any case, on MW you can get away with quite inefficient aerials
because the receiver noise is dominated by sky noise, i.e. noise
received along with the signal. The receiver doesn't have to be very
sensitive, because any signal strong enough to dominate the sky noise
will be quite strong.

At VHF it is different, because the noise generated by the receiver
itself begins to become significant. When you get up to satellite TV
frequencies, receiver noise is dominant, and the other like source is
thermal noise from the ground, trees, and buildings, in view of the antenna.

On 17:09 6 Feb 2022, David Woolley said:

> On 06/02/2022 14:48, Pamela wrote:
>> Thanks for the info. Out of interest, where in life's journey have
>> you gained such knowledge about these things? I imagine any
>> professional work on equivalent modern equipment never needs such
>> methods.
>
> I thought the problem of electrolytic capacitors losing their oxide
> layer with non-use was actually fairly well known.
>
> Electrolytics get their high capacitance by having a very thin oxide
> insulation layer, obtained by basically a corrosion process. In
> normal use they can get away with defects appearing in this layer,
> because the metal re-oxidises and recreates the insulation, but if
> they are left for a long time, the oxide layer can dissolve away,
> such that the current needed to regrow it is too great, and something
> overheats and lets the magic smoke out.

I wasn't referring so much about degradation but about the techniques used
to restore them.

On 07/02/2022 08:45, Roderick Stewart wrote:
>
> I think you need to be "of a certain age" so as to have grown up when
> such electronic construction was the norm, and to have had a natural
> curiosity about all things technical from early childhood. You'd need
> to be inclined to find out about things by (1) getting your hands
> dirty, and (2) reading books - both of course but in that order. You'd
> probably find that a number of us in this newsgroup belong to that
> category, but we're a dying breed.

I stuck my fingers in an empty bedside lamp bulb holder at the age of 4,
and have never looked back.

I spent the first month or so of my life in a hospital incubator, that
had its mains connection stuffed into the 13A wall socket with three
matchsticks.
The NHS are so much better today.

On 07/02/2022 14:59, Mark Carver wrote:
>
> On 07/02/2022 08:45, Roderick Stewart wrote:
>>
>> I think you need to be "of a certain age" so as to have grown up when
>> such electronic construction was the norm, and to have had a natural
>> curiosity about all things technical from early childhood. You'd need
>> to be inclined to find out about things by (1) getting your hands
>> dirty, and (2) reading books - both of course but in that order. You'd
>> probably find that a number of us in this newsgroup belong to that
>> category, but we're a dying breed.
>
> I stuck my fingers in an empty bedside lamp bulb holder at the age of 4,
> and have never looked back.

Ma was fond of telling everyone about a time, which I also vaguely
remember, that my elder brother was vacuuming the hallway of the flat we
were living in at the time, and he came into my room to pull the
extension apart so that he could empty it. Now I didn't know much about
these things aged four, but I was quite sure that those two bits of lead
were supposed to be joined together, so I plugged them back in, and
there was a squeal from the hallway as the machine roared into life. Ma
used to say that I was fascinated by electricity ever after.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 08:45 7 Feb 2022, Roderick Stewart said:

> On Sun, 06 Feb 2022 14:48:48 GMT, Pamela
> <pamela.private.mailbox@gmail.com> wrote:
>
>>> With any old electronic equipment that's working, it's probably a
>>> good idea to power it up every so often to help stop the capacitors
>>> going leaky.
>>
>>Thanks for the info. Out of interest, where in life's journey have you
>>gained such knowledge about these things? I imagine any professional
>>work on equivalent modern equipment never needs such methods.
>
> I think you need to be "of a certain age" so as to have grown up when
> such electronic construction was the norm, and to have had a natural
> curiosity about all things technical from early childhood. You'd need
> to be inclined to find out about things by (1) getting your hands
> dirty, and (2) reading books - both of course but in that order. You'd
> probably find that a number of us in this newsgroup belong to that
> category, but we're a dying breed. I don't know where today's
> youngsters would get anything like the same sort of knowledge, because
> it's possible to see almost anything you might want on a screen
> without ever getting involved, and most of today's electronics doesn't
> readily lend itself to investigation or repair without specialised
> equipment. Whenever I think of this I consider myself lucky that my
> lifetime has so far more or less paralleled the age of television,
> which for practical purposes began with the coronation, when I was
> just old enough to appreciate that television was something special.
>
> Rod.

It's not so much hobbyist electronics and "fixing things" that I was
wondering about ... but more specifically where do you learn to
recondition vintage electronics.

This seems very specialist and unlikely to come up often unless you're in
the trade (which I am assuming Ian isn't).

On Saturday, 5 February 2022 at 18:12:55 UTC, wrightsaerials@aol.com wrote:

> The human brain is like a giant fish. It had gills through which it can
> breathe.

You are Eric Cantona aicmfp

On 07/02/2022 17:53, Roderick Stewart wrote:
> On Mon, 07 Feb 2022 15:56:57 GMT, Pamela
> <pamela.private.mailbox@gmail.com> wrote:
>
>> It's not so much hobbyist electronics and "fixing things" that I was
>> wondering about ... but more specifically where do you learn to
>> recondition vintage electronics.
>
> You know about vintage electronics if you are "vintage" yourself,
> having grown up in the age of thermionic valves, medium wave amplitude
> modulated radio, gramophone records and tape recorders. You gradually
> absorb the knowledge by taking things to pieces to find out how they
> work, learning the hard way which bits not to touch, building kits,
> repurposing components salvaged from junkshops and rubbish tips, and
> reading magazines like Practical Wireless and other similar ones. Then
> you get a job in broadcasting and they teach you even more. I've no
> idea how a youngster would learn this stuff now, except perhaps by
> watching oldies fixing things on Youtube.
>
> Much of what you learn when you are young you never forget. I could
> still tell you the pin connections for an HL2 triode valve, for all
> the use that might be today, though anybody else who needs to know
> would probably be old enough to remember it themselves.
>
> Rod.

Yes, nasty experiences are remembered forever. Like the time I
discovered thet the TopCap connection on one radio valve was actually
the anode, and its 350V hurts even more than the mains 240V :-(

PS - speaking of repurposing components, I discovered that old
eletronics dumped on the bomb-site near where I lived as a child
contained resistors which were .22mm across and ideal for firing from an
air pistol!

Jim

On Mon, 07 Feb 2022 22:39:46 +0000, Indy Jess John
<bathwatchdog@OMITTHISgooglemail.com> wrote:

> contained resistors which were .22mm across and ideal for firing from an
> air pistol!

That seems rather on the small side, so I don't think so.