[TenTec] Delta 580 Questions

Winston F. Jones winjones@ix.netcom.com
Thu, 22 Jun 2000 19:22:13 -0000

I have a Delta 580 and have never had the problems you described. From your
description, the problem is apparently a parasitic oscillation in the final
amp. I'm interested that you have no problems with a dummy load. What type
antenna are you using and what level of SWR? Are  you using open wire
feeders? Is the chassis grounded? I once had a similar problem with an
Argonaut 509, using a Windom antenna. Too much RF was getting back into the
shack and my rig wasn't grounded and no tuner.
Hope this helps.
73, Winston K4CWQ

----- Original Message -----
From: Bob & Linda McGraw K4TAX <RMcGraw@blomand.net>
To: <tentec@contesting.com>
Sent: Thursday, June 22, 2000 04:14 AM
Subject: [TenTec] Delta 580 Questions

> In trying to get an old Delta 580 running I've run into an instability
> on the 10 meter band. The PA takes off into a sing once I hit it with
> some drive.  Reducing the drive to zero does not cause the output to go
> away.  Oscillation is in the 10 meter band, but the PA is maxed out at
> about 90 watts.  ALC light is on.  The only way to stop it is to return
> it to receive.  The PA is stable with a purely resistive load on 10
> meters.  Connect an antenna with a little reactance, bring the drive up
> and it bangs to the rails.  I've checked internal connections etc.
> Removing the output cable from the low level amp to the PA will stop the
> oscillation.  Looking at the output of the low level amp, it seems
> stable with the PA unplugged.
> All other bands look clean and stable.  Any clues or suggestions will be
> appreciated.
> Thanks in advance.
> 73
> Bob K4TAX

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