[TowerTalk] Antenna shift, VHF/UHF matching unit burning out

[Roger (K8RI) on TT]

I think that I've lost a ground.  The SWR has gone sky high on the 
Diamond 144/440 repeater antenna. As the antenna is only rated at 200 
watts the matching network is pretty light duty.  Also, the AV640 which 
originally was very easy to match, is now difficult to find the resonant 
points.

I believe this is due to a DC bias through the matching transformers 
putting the cores into, or near saturation.

I keep using, I think and I believe as I really don't know, but it 
sounds logical.

The new AV840 just arrived and I need to work on the Diamond antenna, so 
I need to find the problem before going any farther with the antennas.

I had been talking to N8ERF on the repeater when he mentioned I was 
getting noisy.  I immediately stopped transmitting, came in, got the SWR 
bridge, took it to the shop and put it in the line. The SWR had gone 
from 1.2:1, to off scale.  I think the finals are OK.  I certainly hope so.

So tomorrow, I'm going to add one of those grounding plates that tie 
everything together and to the station ground. The space behind the desk 
out there is a mass of wire, that could be neatened up, so I can see at 
a glance what is connected to what.

That and all the projects need to be finished up so I have an organized 
shop in which to work.

Any thoughts on the grounding would be appreciated

73

Roger (K8RI)