Re: Unusual Challenge

[Bob La Londe <none@none.com99>]

On 10/22/2021 5:52 AM, ABLE1 wrote:
> Ok Guys!!!  Here you go.  After reading you should
> be ABLE to get a good nights sleep.  :-)
>
> And now for the rest of the story!!
>
> I had installed this setup in 2013 and it worked great with
> some minor issues over the years.  Batteries, switch, etc.
> There were some reports of missed signals but was never sure
> if it was the RF signal loss or the human ear missing the
> burp of the sounder.  It has been just recently that they
> have know that it has been more of an issue and called me
> back to help work out a different plan to get the signals
> better so that they would not miss a customer in the showroom.
>
> When I got there last week as I said I checked the batteries
> and they were a bit low so I replaced with new.  Not that it
> made much difference but it did miss a signal and I thought is
> was due to the fact that I triggered the door to fast.  Assuming
> that the receiver or transmitter had some delay built in for
> excessive trips.
>
> I moved the transmitter to the shop and it worked every time while
> there.  Placed the transmitter back in the attic above the showroom
> and I put the transmitter back in the attic above the showroom where
> it was but staff was in a meeting so I could not test.
>
> Was told later that they tried it and it did not work a total of 3 times
>
> Now the receiver has a wire about 7" long as a antenna.  I have
> it hanging over the edge of a window so that the walls would not block
> the RF signal. The Transmitter is in the attic space on a vertical
> 2x4.  The only thing that might block the signal would be the plywood
> and asphalt shingles on the roof, 70' of distance, bug screen and glass
> window.
>
> Needless to say this is a intermittent problem that is NOW not working!!
>
> Now for the revel!!!
>
> It was mentioned the the bug screen was a metal mesh type.
> And I was asked if that could be causing the problem.  I said
> that I did not think it would but, it certainly would not have any
> bad effects at this time of year to remove the screen.  Well
> they did in the afternoon and did another test and the system
> burped the horn 13 out of 13 times.  ð??® WHAT!!!!
>
> They did this with the window open as well.  They are going to test
> with the window shut the next day to see what the results will be.
>
> They tested with the window closed the and it worked just fine 5 times.
>
> I did some searching online and metal mesh screens as far as I can
> find are not an issue with RF.  That is unless I am involved!!!
>
> What I also found out was that this window is where they put a small
> A/C unit during the summer.  Needless to say they have to remove the
> wire mesh screen to install the A/C and then they re-install the
> screen when they take the A/C out.  If they remember to do so.
>
> So this problem is sometimes there and sometimes not there!!!
> a.k.a.  A intermittent problem!!  Now SOLVED!!!
>
> I strongly suggested that they get the screen frame re-screened with
> a NYLON MESH screen!!!
>
> Hope you enjoyed the story!!
>
> Les
>

That might on depend on the mesh size.  You can can get harmonics.  I
never heard of it being an issue with relatively low frequency stuff,
but in TVRO its one reason why screen mesh dishes are not used with K
band.  Back in the day when we had dual K/C band dishes in order to save
over the cost of a 8-12 foot solid spun dish they would sometimes make a
screen dish around a spun dish.  The screen worked for the C band need
for greater surface area and the spun center worked for the K band. If I
recall it was not a perfect solution, but I got out of satellite
installation for a few years during that time period.

Since the transmitter is remote from the contact, put it outside in a
plastic J box under the eve.  I've done that with LAN WIFI bridges with
good success.  Heat can be an issue, but you don't have to deal with the
same level of heat that I do.  Home Depot used to stock a nice large
plastic J-Box.



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