[Amps] Amps Digest, Vol 70, Issue 21

[John Lyles]

Sorry to add another 2 cents to this, but....

If the plate current meter is after the power supply output terminals, the swinging choke should have nothing to do with this excessive current when you provide RF drive. Sounds a lot like the output stage of the tube is unloaded completely, i.e., open circuit.
73
John
> Message: 3
> Date: Sun, 19 Oct 2008 21:10:13 -0400
> From: "Eddie Bradshaw  KJ4R" <kj4r at ftc-i.net>
> Subject: [Amps] Heathkit Warrior High Plate Current


> I recently bought an "as is" Heathkit HA - 10 Warrior.  The amp is in good overall condition, but I'm having a problem that has me stumped. Here is a little background........ The amp has relays installed for transmit / receive switching and standby bias switching.  The standby bias is around -75v and the bias during transmit is -7v.  The plate current is around 30 ma with the cutoff bias applied which is normal.  When the amp is switched to transmit, the plate current rises to 100ma, which is also normal. I've experimented with adjusting the transmit bias to the recommended -4.5v but it has no effect on the problem.
> 
> The problem arises when I apply even the slightest level of drive to the amp.  The least amount of drive causes the plate current to rise to almost 500ma or higher with very little output power. The tune and load controls seem to have no effect on the plate current.  I've tried the amp on all 5 bands and the problem is the same on each band.  I'm driving the amp with a Kenwood TS 530 (tube output). I suspect the swinging choke may be bad, but I'm not sure how to test or verify it.   Any ideas from anyone who has experience with this amp would be much appreciated.   Eddie KJ4R