Gary Schafer wrote:

I would look at the radio first. Put an ameter in the 12 volt line to
the radio and see how much current it is actually drawing.

73
Gary K4FMX

Actually, I first thought it was an antenna problem, the rig acted just
like I had a bad problem with RF in the shack. I spent all of one
afternoon reworking the grounds and tuning the antenna. I've got the
best-tuned 4BTV in Texas! I tried it on a dummy load and had the same
problem. So, I pulled it off the power supply and ran the rig (Yaesu
FT-990) from the battery in my truck and it works fine. I also tried
the supply on a second rig, a TS-430, with exactly the same problem -
when I transmit the lights on the rig dim and it drops out of lock. The
430 is my mobile rig, it works fine in the truck but not on the PS.

I'll follow you guys' suggestions to start testing parts. I'm in a
fairly small town, so while I bought a 1000uf capacitor today at Radio
Shack, they can't even order an LM723 so I'll have to find someplace
else to get one.

Have any of you guys tried the new switching power supplies? I've seen
the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but
haven't ever used one. I normally just run 1 HF rig (max 100w) and a
small VHF rig (max 25w) for packet. Is a switcher solid and reliable
enough for something like that? I've considered getting something like
that and rebuilding the Astron when I can get the parts.

I have built regulated supplies but it's been 20 yrs since I tinkered
with anything analog, so I'll take all the help I can get! The info at
those links looks helpful, along with the ideas you guys have given me here.

73,
Kerry
WD5ABC