I am looking at adding a weathervane to the roof of my house. The first
location considered is not suitable, as the chimney stacks are too
large and tall for the weathervane.
There is another chimney stack, but it has the TV antenna attached to
one corner. If the weathervane were to be attached to the same chimney
stack, as far away as possible, would there be any likely effects on
the TV signal, either from the stationary 'vane, or when it rotates?

Thanks for any help. I don't want to install the weathervane, and find
that I then get pixellated TV pictures.
--
Davey.

On 22/11/2022 15:09, Davey wrote:
> I am looking at adding a weathervane to the roof of my house. The first
> location considered is not suitable, as the chimney stacks are too
> large and tall for the weathervane.
> There is another chimney stack, but it has the TV antenna attached to
> one corner. If the weathervane were to be attached to the same chimney
> stack, as far away as possible, would there be any likely effects on
> the TV signal, either from the stationary 'vane, or when it rotates?
>
> Thanks for any help. I don't want to install the weathervane, and find
> that I then get pixellated TV pictures.
Will it be within the main lobe of your aerial, and at the same height ?

If not, don't worry

"Davey" <davey@example.invalid> wrote in message
news:tlionb$443a$1@dont-email.me...
> I am looking at adding a weathervane to the roof of my house. The first
> location considered is not suitable, as the chimney stacks are too
> large and tall for the weathervane.
> There is another chimney stack, but it has the TV antenna attached to
> one corner. If the weathervane were to be attached to the same chimney
> stack, as far away as possible, would there be any likely effects on
> the TV signal, either from the stationary 'vane, or when it rotates?
>
> Thanks for any help. I don't want to install the weathervane, and find
> that I then get pixellated TV pictures.

What's the weather vane made of? I have a plastic anemometer (wind speed)
and weather vane (wind direction) mounted on the metal pole to which the TV
aerial is attached. The sensor unit is probably about 2m below the aerial
and stands about 20 cm off the pole. The actual sensors will have some metal
in, but the cups/vane are plastic - maybe deliberately to avoid
satellite/terrestrial signal reflections.

The main problems I've had are:

- The wind unit is a bit low, probably only about 10 cm higher than the
ridge tiles of the roof, which may lead to "boundary effects" with the wind
and the ridge, and hence lower window speeds and maybe some bias on the
direction. Unless I get a longer ladder, I've got it as high as I can.

- Just after I put it up I had a friendly complaint from a neighbour,
because the wind vane caused a dazzlingly bright flashing light as seen from
her house: it was sunlight reflecting off the shiny plastic when the sun was
in a certain direction; I solved it to her satisfaction by sanding the vane
to take off the shine. I'm not sure what angle the sun would have to be to
cause reflections, because her house is due north of mine, so reflections
would only be sent north if the sun was due west or east and the vane was at
45 or (360-45) degrees bearing.

On 22/11/2022 15:23, NY wrote:
> "Davey" <davey@example.invalid> wrote in message
> news:tlionb$443a$1@dont-email.me...
>> I am looking at adding a weathervane to the roof of my house. The first
>> location considered is not suitable, as the chimney stacks are too
>> large and tall for the weathervane.
>> There is another chimney stack, but it has the TV antenna attached to
>> one corner. If the weathervane were to be attached to the same chimney
>> stack, as far away as possible, would there be any likely effects on
>> the TV signal, either from the stationary 'vane, or when it rotates?
>>
>> Thanks for any help. I don't want to install the weathervane, and find
>> that I then get pixellated TV pictures.
>
> What's the weather vane made of? I have a plastic anemometer (wind
> speed) and weather vane (wind direction) mounted on the metal pole to
> which the TV aerial is attached. The sensor unit is probably about 2m
> below the aerial and stands about 20 cm off the pole. The actual
> sensors will have some metal in, but the cups/vane are plastic - maybe
> deliberately to avoid satellite/terrestrial signal reflections.

DTT signals have a guard interval that can cope with displaced signals
arriving with a path difference of around 20 km, unless the device is
going to reflect a distant signal from a hill or building literally
miles away, and that reflection is in the same order of strength as the
'wanted one' (Clue: Almost impossible that would be the case) it really
is totally insignificant.

As for satellite interference, unless it's actually right in the
downlink beam, how could it possibly have any measurable effect ?

On Tue, 22 Nov 2022 15:18:21 +0000
Mark Carver <mark.carver@invalid.invalid> wrote:

> On 22/11/2022 15:09, Davey wrote:
> > I am looking at adding a weathervane to the roof of my house. The
> > first location considered is not suitable, as the chimney stacks
> > are too large and tall for the weathervane.
> > There is another chimney stack, but it has the TV antenna attached
> > to one corner. If the weathervane were to be attached to the same
> > chimney stack, as far away as possible, would there be any likely
> > effects on the TV signal, either from the stationary 'vane, or when
> > it rotates?
> >
> > Thanks for any help. I don't want to install the weathervane, and
> > find that I then get pixellated TV pictures.
> Will it be within the main lobe of your aerial, and at the same
> height ?
>
> If not, don't worry

Not being familiar with antenna design, I had to look this up. The
answer is that the weathervane will be at worst directly behind the
main lobe, quite possibly in the area of the 'back lobe'. It might be
possible to change this so as to get it out of the lobe area. As for
height, it will probably be very close to the height of the antenna.
Material is mild steel.
--
Davey.

On 23/11/2022 08:07, Davey wrote:
> On Tue, 22 Nov 2022 15:18:21 +0000
> Mark Carver <mark.carver@invalid.invalid> wrote:
>
>> On 22/11/2022 15:09, Davey wrote:
>>> I am looking at adding a weathervane to the roof of my house. The
>>> first location considered is not suitable, as the chimney stacks
>>> are too large and tall for the weathervane.
>>> There is another chimney stack, but it has the TV antenna attached
>>> to one corner. If the weathervane were to be attached to the same
>>> chimney stack, as far away as possible, would there be any likely
>>> effects on the TV signal, either from the stationary 'vane, or when
>>> it rotates?
>>>
>>> Thanks for any help. I don't want to install the weathervane, and
>>> find that I then get pixellated TV pictures.
>> Will it be within the main lobe of your aerial, and at the same
>> height ?
>>
>> If not, don't worry
> Not being familiar with antenna design, I had to look this up. The
> answer is that the weathervane will be at worst directly behind the
> main lobe, quite possibly in the area of the 'back lobe'. It might be
> possible to change this so as to get it out of the lobe area. As for
> height, it will probably be very close to the height of the antenna.
> Material is mild steel.
I really wouldn't worry about it then, it's only going to be a problem
it it obstructs your signal, which with it behind the aerial, isn't
going to be happening .

Get a plastic Weather vane.
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.!
"Davey" <davey@example.invalid> wrote in message
news:tlionb$443a$1@dont-email.me...
>I am looking at adding a weathervane to the roof of my house. The first
> location considered is not suitable, as the chimney stacks are too
> large and tall for the weathervane.
> There is another chimney stack, but it has the TV antenna attached to
> one corner. If the weathervane were to be attached to the same chimney
> stack, as far away as possible, would there be any likely effects on
> the TV signal, either from the stationary 'vane, or when it rotates?
>
> Thanks for any help. I don't want to install the weathervane, and find
> that I then get pixellated TV pictures.
> --
> Davey.
>

Yes I used to have rotating aerials just above a parabeam and saw no changes
in signals on the wanted channels as the aerial rotated. I think designers
try to stop off axis in all direction gain lobes so that traffic in the road
does not affect the reception.
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.!
"Mark Carver" <mark.carver@invalid.invalid> wrote in message
news:ju48g0FuajiU4@mid.individual.net...
> On 22/11/2022 15:23, NY wrote:
>> "Davey" <davey@example.invalid> wrote in message
>> news:tlionb$443a$1@dont-email.me...
>>> I am looking at adding a weathervane to the roof of my house. The first
>>> location considered is not suitable, as the chimney stacks are too
>>> large and tall for the weathervane.
>>> There is another chimney stack, but it has the TV antenna attached to
>>> one corner. If the weathervane were to be attached to the same chimney
>>> stack, as far away as possible, would there be any likely effects on
>>> the TV signal, either from the stationary 'vane, or when it rotates?
>>>
>>> Thanks for any help. I don't want to install the weathervane, and find
>>> that I then get pixellated TV pictures.
>>
>> What's the weather vane made of? I have a plastic anemometer (wind speed)
>> and weather vane (wind direction) mounted on the metal pole to which the
>> TV aerial is attached. The sensor unit is probably about 2m below the
>> aerial and stands about 20 cm off the pole. The actual sensors will have
>> some metal in, but the cups/vane are plastic - maybe deliberately to
>> avoid satellite/terrestrial signal reflections.
>
> DTT signals have a guard interval that can cope with displaced signals
> arriving with a path difference of around 20 km, unless the device is
> going to reflect a distant signal from a hill or building literally miles
> away, and that reflection is in the same order of strength as the 'wanted
> one' (Clue: Almost impossible that would be the case) it really is totally
> insignificant.
>
> As for satellite interference, unless it's actually right in the downlink
> beam, how could it possibly have any measurable effect ?

On Wed, 23 Nov 2022 09:14:39 -0000
"Brian Gaff" <brian1gaff@gmail.com> wrote:

> Get a plastic Weather vane.
> Brian
>

The one I am thinking of getting is a bespoke one, which only comes in
mild steel.
--
Davey.

On 23/11/2022 09:28, Davey wrote:
> On Wed, 23 Nov 2022 09:14:39 -0000
> "Brian Gaff" <brian1gaff@gmail.com> wrote:
>
>> Get a plastic Weather vane.
>> Brian
>>
> The one I am thinking of getting is a bespoke one, which only comes in
> mild steel.
I'd be more worried about rust stains all over your roof tiles

On 23/11/2022 08:15, Mark Carver wrote:
> I really wouldn't worry about it then, it's only going to be a problem
> it it obstructs your signal, which with it behind the aerial, isn't
> going to be happening .

A lot of these answers are treating the antenna as a point source, with
only far field behaviour.

If the vane is close enough to be in the near field, the effects could
be difficult to predict.

A metal object behind the aerial, could reflect signals, and at some
distances, the reflection could cancel the wanted signal.

If you consider a typical yagi, the directors are in front of the main
dipole, but rather than block it, they enhance the signal, so blocking
by a near field object could go either way.

On Wed, 23 Nov 2022 11:30:23 +0000
David Woolley <david@ex.djwhome.demon.invalid> wrote:

> On 23/11/2022 08:15, Mark Carver wrote:
> > I really wouldn't worry about it then, it's only going to be a
> > problem it it obstructs your signal, which with it behind the
> > aerial, isn't going to be happening .
>
> A lot of these answers are treating the antenna as a point source,
> with only far field behaviour.
>
> If the vane is close enough to be in the near field, the effects
> could be difficult to predict.
>
> A metal object behind the aerial, could reflect signals, and at some
> distances, the reflection could cancel the wanted signal.
>
> If you consider a typical yagi, the directors are in front of the
> main dipole, but rather than block it, they enhance the signal, so
> blocking by a near field object could go either way.

The maximum distance between the antenna pole and the weathervane pole
would be less than 2 feet, and then the direction arms and the
revolving part would be considerably nearer.
It does sound as though there is too much to risk, especially with a
bespoke weathervane, which could not be returned fro a refund if it
affected the signal
I may have to abandon this idea. At least I have investigated it.
Thanks for the answers, everyone.

--
Davey.

On 23/11/2022 11:30, David Woolley wrote:
> On 23/11/2022 08:15, Mark Carver wrote:
>> I really wouldn't worry about it then, it's only going to be a
>> problem it it obstructs your signal, which with it behind the aerial,
>> isn't going to be happening .
>
> A lot of these answers are treating the antenna as a point source,
> with only far field behaviour.
>
> If the vane is close enough to be in the near field, the effects could
> be difficult to predict.
>
> A metal object behind the aerial, could reflect signals, and at some
> distances, the reflection could cancel the wanted signal.

Explain how with a COFDM signal using 8000 separate carriers, and a
guard interval that is 'kms' (NOT mm) wide for path length   ?

On 23/11/2022 12:07, Mark Carver wrote:
> Explain how with a COFDM signal using 8000 separate carriers, and a
> guard interval that is 'kms' (NOT mm) wide for path length   ?
Gain aerials wouldn't work at all if that were a let out!
When you get multipath with COFDM, the guard interval is protecting you
against interference between signalling units, which are transmitted
quite slowly (the baud rate, in the true meaning of that, is low).
It doesn't protect you against phasing effects within a single
signalling unit, which are sensitive to distances of the order of the
carrier wavelength. COFDM survives these because only some frequencies
are cancelled sufficiently to make them unusable, assuming a reasonable
starting SNR. If the path difference is of the order of wavelength
equivalent of the channel spacing (~37m), or greater, only some
sub-carriers will be unusable.
Individual bits will be spread across sub-carriers in such a way that
the error correction can make up for a small number of missing sub-carriers.
However, once you are in, or close to the near field, the cancellation
will spread over many multiplexes, so all the sub-carriers in a
particular multiplex can become unusable.

"Davey" <davey@example.invalid> wrote in message
news:tll1st$c5oq$1@dont-email.me...
> The maximum distance between the antenna pole and the weathervane pole
> would be less than 2 feet, and then the direction arms and the
> revolving part would be considerably nearer.
> It does sound as though there is too much to risk, especially with a
> bespoke weathervane, which could not be returned fro a refund if it
> affected the signal
> I may have to abandon this idea. At least I have investigated it.
> Thanks for the answers, everyone.

What a shame. I hope you manage to find a solution: either a non-metallic
vane near the aerial or else a metallic one on a mounting that is out of the
aerial's "field of view".

On Wed, 23 Nov 2022 14:21:08 -0000
"NY" <me@privacy.invalid> wrote:

> "Davey" <davey@example.invalid> wrote in message
> news:tll1st$c5oq$1@dont-email.me...
> > The maximum distance between the antenna pole and the weathervane
> > pole would be less than 2 feet, and then the direction arms and the
> > revolving part would be considerably nearer.
> > It does sound as though there is too much to risk, especially with a
> > bespoke weathervane, which could not be returned fro a refund if it
> > affected the signal
> > I may have to abandon this idea. At least I have investigated it.
> > Thanks for the answers, everyone.
>
> What a shame. I hope you manage to find a solution: either a
> non-metallic vane near the aerial or else a metallic one on a
> mounting that is out of the aerial's "field of view".
>

There is no other useable spot, There is a third chimney breast, but it
is out of the normal field of view, and so would be pointless. I will
ask about a plastic weathervane, though, before I terminate the idea.
There is always the garage roof, but it is surrounded by trees taller
than it, so would be of no use. A bit like installing a sundial in the
shade.

--
Davey.

On Wednesday, 23 November 2022 at 11:58:23 UTC, Davey wrote:

> It does sound as though there is too much to risk, especially with a
> bespoke weathervane, which could not be returned fro a refund if it
> affected the signal
> I may have to abandon this idea. At least I have investigated it.
> Thanks for the answers, everyone.
>
> --
> Davey.

In all my many years of TV aerial installation I've never had this problem. There are lots of large metal chimney cowls that move round when the wind changes and I've never known of one causing a problem. Many schools have weather vanes and they don't cause a problem. In the worst case scenario the weather vane might cause a reflection that arrived at the aerial exactly out of phase with the main signal, but even so that would merely cause a small fluctuation in signal strength which would have no effect on reception, because the reflection wouldn't be anywhere near as strong as the main signal, so significant phase cancellation wouldn't happen.
Some years ago I carried out a lot of surveys of the effects of ginormous wind turbines on TV reception. Once digital came along it was next to impossible to find any such effects because of the way digi works. There were zero effects from reflections off the whacking great blades. You could see the slight fluctuations in signal level on the analyser but it was never anywhere near enough to affect reception. It was possible to get visible-on-the-screen effects when the signal was very weak and the path was through the area encompassed by the blades, but that was all.
Buy your weathervane and get it installed. In the stupendously unlikely event that it affects your TV reception consider:
1. moving the TV aerial up or down a bit
2. Installing a slightly taller mast than you envisaged, with the weather vane at the top and the TV aerial beneath it, or vice versa. But it won't happen.
Bill

On Wed, 23 Nov 2022 19:20:03 -0800 (PST)
"wrightsaerials@aol.com" <wrightsaerials@f2s.com> wrote:

> On Wednesday, 23 November 2022 at 11:58:23 UTC, Davey wrote:
>
> > It does sound as though there is too much to risk, especially with
> > a bespoke weathervane, which could not be returned fro a refund if
> > it affected the signal
> > I may have to abandon this idea. At least I have investigated it.
> > Thanks for the answers, everyone.
> >
> > --
> > Davey.
>
> In all my many years of TV aerial installation I've never had this
> problem. There are lots of large metal chimney cowls that move round
> when the wind changes and I've never known of one causing a problem.
> Many schools have weather vanes and they don't cause a problem. In
> the worst case scenario the weather vane might cause a reflection
> that arrived at the aerial exactly out of phase with the main signal,
> but even so that would merely cause a small fluctuation in signal
> strength which would have no effect on reception, because the
> reflection wouldn't be anywhere near as strong as the main signal, so
> significant phase cancellation wouldn't happen. Some years ago I
> carried out a lot of surveys of the effects of ginormous wind
> turbines on TV reception. Once digital came along it was next to
> impossible to find any such effects because of the way digi works.
> There were zero effects from reflections off the whacking great
> blades. You could see the slight fluctuations in signal level on the
> analyser but it was never anywhere near enough to affect reception.
> It was possible to get visible-on-the-screen effects when the signal
> was very weak and the path was through the area encompassed by the
> blades, but that was all. Buy your weathervane and get it installed.
> In the stupendously unlikely event that it affects your TV reception
> consider: 1. moving the TV aerial up or down a bit 2. Installing a
> slightly taller mast than you envisaged, with the weather vane at the
> top and the TV aerial beneath it, or vice versa. But it won't happen.
> Bill

Well, thanks, Bill. I'll think about this. The scaffolding against
that wall, which will be used for the sundial and clock, won't be built
until the spring, so I have plenty of time.
By the time I'm finished, I'll have a turret clock face and a sundial
on the same wall, and a weathervane directly above!
A shame my wife died during the summer, she won't see any of this.
--
Davey.

On 23/11/2022 12:23, David Woolley wrote:
> On 23/11/2022 12:07, Mark Carver wrote:
>> Explain how with a COFDM signal using 8000 separate carriers, and a
>> guard interval that is 'kms' (NOT mm) wide for path length   ?
>
> Gain aerials wouldn't work at all if that were a let out!
>
> When you get multipath with COFDM, the guard interval is protecting
> you against interference between signalling units, which are
> transmitted quite slowly (the baud rate, in the true meaning of that,
> is low).
>
> It doesn't protect you against phasing effects within a single
> signalling unit, which are sensitive to distances of the order of the
> carrier wavelength.  COFDM survives these because only some
> frequencies are cancelled sufficiently to make them unusable, assuming
> a reasonable starting SNR.  If the path difference is of the order of
> wavelength equivalent of the channel spacing (~37m), or greater, only
> some sub-carriers will be unusable.
>
> Individual bits will be spread across sub-carriers in such a way that
> the error correction can make up for a small number of missing
> sub-carriers.
>
> However, once you are in, or close to the near field, the cancellation
> will spread over many multiplexes, so all the sub-carriers in a
> particular multiplex can become unusable.
Well, and I see Bill has jumped in with his eons of practical
experience, I'm not disputing there wouldn't be reflected signals
produced, the point is no aerial (tx or rx) lives in splendid isolation,
they are all subject to no end of static and dynamic reflective clutter
that is nearby, but the decoding (because of the parameters selected)
sorts it out.

I install CODFM based wireless mics and cameras in TV studios. The Rx
antennas are often up in the lighting grid, in a jungle of metal work.
I've never heard or seen disturbance, and the devices often carry on
with useful output a surprising distance away from the studio....

On 24/11/2022 10:37, Mark Carver wrote:
> I'm not disputing there wouldn't be reflected signals produced, the
> point is no aerial (tx or rx) lives in splendid isolation

Traditional Yagi TV aerials can be considered to be a dipole aerial not
in isolation, but rather surrounded by a dozen or so pieces of metal.
The polar diagram, and therefore gain, of an isolated dipole is very
different from that of the complete Yagi with all of its directors and
reflectors.

> I install CODFM based wireless mics and cameras in TV studios.

Do they also claim to have MIMO on the fixed part? That allows the
receiver to switch between aerials if one falls into a local quiet spot.
I imagine they also have rather a good noise margin.

On Thursday, 24 November 2022 at 08:24:41 UTC, Davey wrote:

> A shame my wife died during the summer, she won't see any of this.
> --
> Davey.
My wife was really worried about the frequent intruders so we decided to install automatic gates and high fences. She sat in the wheelchair many times and watched me as I did the preparatory work, but she didn't live to see the gates installed and working. It was upsetting because it was something I did for her.
Bill

On Thursday, 24 November 2022 at 10:37:34 UTC, Mark Carver wrote:

> Well, and I see Bill has jumped in with his eons of practical
> experience, I'm not disputing there wouldn't be reflected signals
> produced, the point is no aerial (tx or rx) lives in splendid isolation,
> they are all subject to no end of static and dynamic reflective clutter
> that is nearby, but the decoding (because of the parameters selected)
> sorts it out.

That, in a nutshell, is why DTT works so well, and is also part of the reason why it can manage with a 20dB lower signal level than analogue, and why some installers are now happily using tiny log periodics that have poor directional characteristics. Assuming a decent aerial you don't see aeroplane flutter with DTT, but with analogue it used to be a right nuisance near airports and aerodromes. Likewise flutter from goods trains* is no longer a problem.
*flutter from reflections; if the signal path if only just above track level a train will cause the signal to come and go and the nulls can be deep enough to prevent reception. Same applies to ships in river estuaries (Belmont reception in Hull for instance).

On Thursday, 24 November 2022 at 18:58:00 UTC, wrightsaerials@aol.com wrote:
To clarify:
if the signal path is only just above track level and crosses the tracks so the trucks screen the rx ae from the tx a train will cause the signal to come and go and the nulls can be deep enough to prevent reception. At the moment when the signal path is obstructed by the truck or carriage the ratio between the direct signal and the sum of reflected signals, CCI, and random interference will obviously drop, and if it drops far enough reception will, to use a riggers' technical term, be buggered. But when the signal path cannot be directly obstructed by the train (or other big moving thing*) the fluctuating reflections from it just don't ever (in my experience) cause visible effects on reception. Having said that, hypothetically if the direct signal path was permanently obstructed by topography and the path from tx to railway track was line-of-sight and there was LOS from track to rx, it could happen. But I've never seen it. And reception would be shite anyway.
Bill

On Thu, 24 Nov 2022 10:47:54 -0800 (PST)
"wrightsaerials@aol.com" <wrightsaerials@f2s.com> wrote:

> On Thursday, 24 November 2022 at 08:24:41 UTC, Davey wrote:
>
> > A shame my wife died during the summer, she won't see any of this.
> > --
> > Davey.
> My wife was really worried about the frequent intruders so we decided
> to install automatic gates and high fences. She sat in the wheelchair
> many times and watched me as I did the preparatory work, but she
> didn't live to see the gates installed and working. It was upsetting
> because it was something I did for her. Bill

You have my sympathy, it's tough.
--
Davey.

In article <tlnk6r$l3v9$1@dont-email.me>, David Woolley
<david@ex.djwhome.demon.invalid> wrote:
> On 24/11/2022 10:37, Mark Carver wrote:
> > I'm not disputing there wouldn't be reflected signals produced, the
> > point is no aerial (tx or rx) lives in splendid isolation

> Traditional Yagi TV aerials can be considered to be a dipole aerial not
> in isolation, but rather surrounded by a dozen or so pieces of metal.
> The polar diagram, and therefore gain, of an isolated dipole is very
> different from that of the complete Yagi with all of its directors and
> reflectors.

Its a shame in a way that people use 'effecive area' when describing how an
antenna can have 'gain' as it may distract people from realising that the
interaction alters and is sensitive to the field over a *volume* of space
around the antenna. The higher the gain, the bigger this volume becomes
where the field isn't the same as for an an unaffected 'plane wave' from a
far source.

Behind a high gain antenna there may be a near-null away from the antenna
on its extended beam axis. But you'd need to be more cautious of an
extended object there closeby there at the 'back'. Even more so for
off-boresight nearby the front. You'd need to consider near-field
interactions.

Never experimented, though. So just giving the theory that may have an
impact. In practice "how close is too close?" or "How big is too big?"
depend on details.

Jim

--
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