[222mhz] RFI on 222mhz

[Paul]

I've finally stumbled on a problem that has me stumped. I am using an Icom
IC-706MkII as the 28.0mc if into an Elecraft XV-222, into a TE systems
2210G, feeding a M2 222-10EZ at 45 foot thru  82 feet of LMR-400. The
problem is RF interference heard thru the IC-706 when transmitting using the
TE 2210G. The audio level of the interference remains the same regardless of
the position of the audio control including fully down/clockwise. The
siginificant thing is that the level of the interference varies with the
direction of the antenna. The tower/antenna is offset from the shack by
about 25 feet horizontal distance and 55 feet vertical distance (shack in
basement). The interference is strongest when the antenna is pointed
directly at the location of the station. As the antenna is rotated left or
right of a direct bearing to the shack, the interference begins to reduce
until at about 20 degrees left or right, it is nearly gone, and by 30
degrees left or right it has completely disappeared. Transmitting barefoot
with the XV-222 only (23 watts), there is no interference regardless of
antenna bearing. Reducing the drive to 1 watt from the XV-222 into the
TE-2210G still provides about 80 watts out and the interference level
remains about the same. I have changed power supplies, I have changed power
and RF interconnect cables between all the gear including varying cable
lengths and run positions. I have also changed the if transceiver to use my
TS-690S. The problem remained, this time being heard on the TS-690S. The
interference is only heard on the radio being used as the if. Everything is
well grounded. The coax cable run is offest from the bearing to the shack,
the interference is not strongest when the antenna is in a direct bearing
line over the coax run, but is strongest with the bearing directly pointed
at the shack. 

 

I am certainly open to any suggestions and ideas on how to troubleshoot this
problem.

 

73, Paul W2EC