|[AMRadio] Heath Apache symptoms|
bguyger at sbcglobal.net
Wed Jan 7 22:40:19 EST 2009
I can say Amen to this. One of the biggest failure modes for Heath kits is loose hardware. I've heard this many times on the Heathkit reflector.
I bought an Apache for parts to fix one I had bought earlier and did not find ONE screw that was beyond finger tight. Whoever had this unit attempted to fix DC, RF and or audio problems by running a bare 18 ga. copper wire ground buss through the entire transmitter even in the VFO box.
If at first you don't succeed, try really goofing it up!
It all worked out well for me, the first Apachie was immaculent inside (someone had hacked a big hole in the cabinet for what was probably a muffin fan or some such. and most of the original knobs were gone) and the second was immaculent outside, so between them both you see I licked the platter clean..I mean have a complete transmitter.
----- Original Message ----
From: James M. Walker <chejmw at buffalo.edu>
To: Discussion of AM Radio in the Amateur Service <amradio at mailman.qth.net>
Sent: Wednesday, January 7, 2009 8:25:02 PM
Subject: Re: [AMRadio] Heath Apache symptoms
If I might make a suggestion,
Check the ground lugs around the clamp tube and vicinity.
Make sure they are tight, and also check for any signs of
"Three working Apaches and counting."
----- Original Message -----
From: "Mike Sawyer" <w3slk at verizon.net>
To: <k5pgw at yahoo.com>; "Discussion of AM Radio in the Amateur Service"
<amradio at mailman.qth.net>
Sent: Wednesday, January 07, 2009 9:08 PM
Subject: Re: [AMRadio] Heath Apache symptoms
> Hmmm, as an Apache man my self, 9 chances out of 10 I would say check out
> and around that clamp tube. It almost sounds directly related to heat, (Ip
> goes up the longer the radio is keyed). Might be some bad R's. When you
> it, post your findings here since I for one would be very interested.
> ----- Original Message -----
> From: "John King" <k5pgw at yahoo.com>
> To: <amradio at mailman.qth.net>
> Sent: Wednesday, January 07, 2009 7:03 AM
> Subject: [AMRadio] Heath Apache symptoms
> Hello, fellow AM folks! I would like to hear from those intimately
> with the Heath Apache.
> I think my Apache needs some TLC. It is working and gets good reports on
> strength and audio, however:
> I note that when keyed up, after loading and dipping the finals, that the
> plate current starts out lower than the tune up and then starts creeping
> My experience over 50 years as a Ham has convinced me that creeping plate
> current is usually a sign of screens in the final tubes going bad. In fact
> once had a Hallicrafters HT 32B that had creeping plate current when the
> 6146 tube screens began going bad. In fact, if I didn't increase the bias
> on the tubes, they would eventually "run away" and self destruct. The
> in my Apache do not "run away" they just go from lower current at tune up
> and rise to slightly more current than at tune up.
> I think that my grid drive is also marginal because it takes all the
> available grid drive to set it at the rated and desired level of drive.
> drive control must be at extreme maximum, fully clockwise. This could be
> related to "creeping plate current". What do you think?
> In addition, I note some downward movement of the plate current of the
> amplifier upon modulation. Lack of grid drive may cause this problem if I
> remember correctly. In addition, I seem to feel that over coupling of the
> output of the final tank circuit might also contribute to the downward
> modulation? I recently replaced the 6AQ5 clamper tube but did not readjust
> the circuit after replacement.
> I would like some input from you who have the knowledge and experience to
> discuss these symptoms. I want to have this discussion before I start
> to wrestle this Green Monster out of its' cabinet. I am not as strong as I
> was when I became a Novice over 50 years ago. Before you laugh, let me say
> that if you are LUCKY, maybe you will live to get WEAK!! Hi!! HI!! You may
> address this issue off the reflector if you prefer. I don't want to bore
> other members with a topic that may not be of interest to them. After all,
> the majority of hams feel that AM is a relic of the past. I enjoy AM, SSB
> and CW. Thanks in advance and 73, John, K5PGW
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