REAL MYSTERY---HELP!!

[AI0F]

I have a good one on my hands! All worked perfect in the shack, sent my 950SDX off for a general tune-up. When received back, the radio works great..but, I put in right back in the same place, nothing has changed, and now have an S9+ solid noise level on all 3 of my rigs..the 950, IC-746, and IC-718. I have checked all coax connections and coax, have a very good grounding system consisting of commercial strap and heavy leads, all going to 00 welding cable to an 8'grouding rod right outside the window. If that isn't enough, here's a real dandy...the 950 runs off it's internal PS, the other two from an Astron 50A 12V PS..when you key the rigs on 40M, the Astron  trips off!! Again, never had any problem before, and nothing has changed.. can anyone offer any explanations or help???

Tnx in advance....Tom KF0K

[N3OX]

Can you post a recording of the noise?

Were you off the air when you had the 950SDX out or where you using the '718 and the '746 while you didn't have the '950?  Was there really a correlation with reinstalling the '950 like you listened the evening before you put the '950 back and there was no noise and then when you fired up the rigs the next day after putting things in place, you had noise?

You might want to go through the RFI-location checklist at:

http://rfiservices.com/tips.htm

Because an S9+ noise level is fairly likely to be coming from your own house.

The basic idea is to run the rig from a battery and shut down the rest of the house.

- - - - - -

The astron tripping off on 40m suggests that something *has* changed with your antenna system somehow.  Do you use antennas where you'd notice SWR changes directly?  Losing a coax shield connection while using a tuner to match your antennas could cause a huge noise ingress and RF getting into the Astron.  Astron supplies are fairly prone to tripping off if you run RF currents through them. My VS-35M used to shut down on 30m all the time when I was using an end-fed wire.

Dan

[AI0F]

Dan,
Tnx for your reply...yes, I used both the IC-746 and IC-718 while the 950 was "disconnected". I have the yagi and dipoles fed into a Delta-4 coax switch, also the 3 rigs through another Delta-4...so, all antennas work with all rigs. I've been over and over all the equipment, I just can't find or figure what is different...will do some checking elsewhere!

Tnx again,
Tom KF0K

[N3OX]

Some possibly helpful sound files to give you some ideas:

http://www.arrl.org/tis/info/HTML/rfi-noise/

Dan

[K4SAV]

Sounds like the Astron has developed a problem.  With this much equipment, isolating the problem to one piece of equipment should be easy.

Jerry, K4SAV

[AF4O]

My Astron 50a (with the meters, this gave an indication to the problem) in the beginning had loose connections from the factory and acted similar to this. Then years later developed an arc on the regulator board.

For the first i went over it and tighteded/resoldered anything suspicious. Then the last problem, cleaned the circuit board up with a fine wire brush and deoxit.

Use all appropriate safety precautions!

Mine is humming along fine now.

73
Chuck
AF4O