For an easy test that will tell you a lot, try a
substitute transmitter. Does a different transmitter
do the same grunge?
Disable and remove your main transmitter and pa from
the coax path. Use a temp mobile or an equiv for
testing. Tx on the main repeater tx frequency with
the sub transmitter and listen for the grunge.
You said you changed out the duplexers and tried a
different antenna. The only thing I didn't see swapped
was the transmitter, PA and receiver. I would first
try swapping out the transmitter side. Do you have
a circulator/isolator in line?
If you were able to measure the grunge on the receiver
side, you could then reduce the tx power to 1 watt
or something easy to deal with. Then place a high power
pad (attenuator) in series between the tx equipment
and the duplexer to measure any change in the grunge
with the added pad.
skipp
> Fraser Stuart <[EMAIL PROTECTED]> wrote:
>
> We have a 145 Mhz 600khz split repeater running 25 Watts output up
LDF 450 coax to a three element commercial beam at 25 Metres above
ground mounted on a metal 35 Meter tower,,,
> We are trying to identify the problem of what could be a "Rusty
Bolt effect" the effect is that it will wipe out a signal on the input
of all but the very very strong signals it sounds just like a heavy
crunching sound,,,,it does not become worse with rain, wind,cold,or
heat,,,,,we have changed the Tx/Rx set up, and changed the Wacom
Duplexer..added extra bandpass filters
>
> We have another beam 3 Meters below, run the system on this with
the same effect, have run the repeater with two antennas and extra
filtering, also the effect is present with only 1 watt of RF output,,,,
>
> one other effect the noise can be heard on the Tx carrier ie no
through audio,,
>
> To investigate the mast will cost money for an insured rigger,,,
>
> idea's where or what to try next would be greatfully recieved,,
>
> rgds Fraser
>
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