On Thu, Oct 29, 2009 at 1:45 PM, Joe wrote:
> Mike Besemer (WM4B) wrote:
>>
>> Joe,
>>
>> The problem isn’t traffic dependant (10 am being a busy time), as I
>> monitor on and off all day and there is PLENTY of traffic all day
>> long. It seems to have more to do with temperature. You can clearly
>> hear the signals come on and fade off frequency
>>
> I had thought that you said that 10AM seemed to be a particularity bad
> time of interference. 10AM does not seem to be a time that the heat
> load of a site would be high. If the site was overheating, I would
> think that interference would be worse in the afternoons.
As I mentioned, the interferrence is moving. At a certain temperature,
it sweeps through our repeater input. As the temperature rises, it
seems to move on.
>>
>> It’s also easy to hear which transmitter is sending the pages. I have
>> two dual band radios in my vehicle. Typically one is on the repeater
>> output, one on the input, one of VHF paging and one on UHF paging.
>> It’s also been confirmed by having the owner send test bursts by
>> specific transmitters.
>>
> OK, important question. Is the particular paging company you are
> working with to resolve the problem ALWAYS involved in the
> interference?
No, but being the strongest signals in the area, they are the primary
source of frustration.
>>
>> The other two UHF frequencies are also paging transmitters.
>>
>
> How are the other two UHF frequencies involved in the interference?
> When the two UHF freqs are involved, is the above mentioned paging
> company ALSO involved?
Not necessarily
>>
>> Good thoughts about the transmitter self-oscillating when unkeyed...
>> that’s another road we can go down.
>>
> I would guess that if the interference is caused by an
> self-oscillating transmitter, it would be probably be in the VHF range
> of frequencies. That way the signal could get out of the transmitter
> through any filtering that may be involved. Just a guess, mind you.
>>
>> Speaking of going down roads… what I really need is more help!
>> Several of our club members are engaged in assisting, but what I
>> really need is a dedicated team of folks. Having to work for a living
>> is taking a serious bite out my tracking time!
>>
> Someone needs to do some directional finding on the interfering
> signal, then triangulate. If I were to guess at a location I would
> look up the the geographical location in your area of all the
> frequencies involved. 152.480, 462.775, 462.850 and 462.925Mhz. You
> may find that they share the same location or are very close to each
> other. Start looking there. Or go to the site that the paging company
> is at and look for interference.
Working it. Not getting nearly enough help though.
>
> You said that you are on a water tank. Water tanks are notorious for
> co-site interference because all of the antennas are usually on the
> top of the tank and are in the same horizontal plane. In other words,
> no vertical separation. Keep this in mind as I found my problem at our
> water tank site by momentarily shutting down the water company
> telemetry radio (with their permission) and the interference went
> away. The problem was that the VHF telemetry antenna and the 6 meter
> ham antenna were only about 10 feet apart.
We're the only one on the site.
>
> 73, Joe, K1ike
>
>
>
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