[TowerTalk] station to station interference

[Roger (K8RI) on TT]

I think Ed has some good advice.

Although this was for VHF the concept, already mentioned is applicable 
to mot any band and/or mode.
The wide area repeater was located in my garage. The antenna 
(Shakespeare commercial) was on top of the 90 ft tower behind the garage.
The tower had a tribander on it as well and was guyed with a small EHS 
(Don't remember the size, bit IIRC it was less than a quarter in, so 
probably 3/16ths.
The guys were broken up with large insulators. The bottom ends had an 
insulator, maybe 5' or more from the anchor. That was 30 years ago, so 
recollections are a bit hazy<:-)

I discovered that rubbing an 8 or 10" screwdriver on the guy above the 
bottom insulator would completely wipe out a 50W mobile only 2 or so 
miles distant.
So, "I think" somewhere in the system was a poor connection (shield to 
ground? Didn't even need to be on that bad, something in the wire 
antennas, or tribander)  I did discover (later on) the SWR on a simple 
3L tribander that used a fiber center insulator, with 1/4" SS screws 
into each side of the DE for a direct feed. No balun or matching 
network. One side was no longer making contact. That leaves me guessing 
that connection was probably the source of the de-sence.

Even old fences are notorious for rectification when located near the 
antennas
All our fences are plastic as the don't keep anything in, or out.

A garden is impossible as we have woods on two sides of the yard and the 
critters get the vegetables before we do. Our neighbors gave up too.

The neighbors still connected TV antenna pre-amp in the attic with no AB 
switch is now rare with cable and satellite, but there are cases where 
someone has left an outside TV antenna connected to the TV set along 
with the other service.

73

Roger (K8RI)


On 9/28/2016 Wednesday 8:54 AM, Ed Sawyer wrote:
> I would advocate "going clean" on the worst offender scenario and have pure
> coax going from the amp to the antenna.  Same on the receive circuit and see
> if it goes away.  You might hear a clean harmonic now but does the broadband
> noise go away.  If it doesn't, you have just eliminated a SLEW of
> possibilities.  If it does, add things back one at a time and observe.
>
>   
>
> This has worked for me.
>
>   
>
> By the way, I don't need stubs - I have found out.  Just Bandpass filters
> and antenna separation.  1.5kW on all bands and SO2R.
>
>   
>
> Ed  N1UR
>
> _______________________________________________
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>
>
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-- 

73

Roger (K8RI)


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