[Boatanchors] KWM2A

[Al Parker]

Hi Bill,
	I've owned several KWM-2(+A)'s in the last 10 yrs, and maybe worked on 
a few others.  I don't consider myself an authority on them, they are 
very intricate.
	My first suspect in a case like this is the bandswitch and the mode 
switch.  They have small contacts, and in many sections don't switch 
much current and don't self clean very well.  Working them thru all 
positions several times sometimes works wonders.  If your problem is on 
all bands, it's probably not from this cause.
	My second thought in your case has been mentioned, resistors.  In 
particular, both the dropping resistors in the driver's screen and plate 
ckt.  They may have just drifted to high values, or may be badly 
overheated and intermittent,opening up after some load is applied.
	I hope this gives you some helpful things, maybe you've already been there.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 1/5/2015 4:07 PM, Bill and Liz wrote:
> I’m playing with a KWM2-A which has intermittent drive problems.  After turn-on, it may or may not produce grid current and, if it does, after a few cycles the drive disappears “until next time”.  Drive is always available up to the grid of the driver tube-the intermittent condition is after that.  I can find no blown or damaged components.  The only clue is that when drive is available it starts with a decent reading and then declines fairly quickly to about 1/3 of the initial meter reading.  I have tested the driver tube ; screen and plate voltages are always the proper value.  It is possible that it is a relay problem (driver tube is biased off in receive and switched by K2) but I inspected the relay, cleaned the contacts with paper and NuTrol and even rapped the relay with a screwdriver when drive disappeared, all to no avail.
>