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 arcing.
Jim WB2FCN "Three working Apaches and counting." ----- Original Message ----- From: "Mike Sawyer" <[email protected]> To: <[email protected]>; "Discussion of AM Radio in the Amateur Service" <[email protected]> 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 > in > 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 > find > it, post your findings here since I for one would be very interested. > Mod-U-Lator, > Mike(y) > W3SLK > ----- Original Message ----- > From: "John King" <[email protected]> > To: <[email protected]> > 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 > familiar > 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 > up. > 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 > I > 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 > finals > 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. > The > 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 > final > 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 > trying > 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 > the > 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 > > > > > > > > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > > ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body.
