[Heathkit] AT-1 rebuild continues...

[kwylow zinjanthropus]

All:
Started on the wiring yesterday. I spent part of weekend at Camp San Luis Obispo on a cheap space-A room and concentrated on two things: studying for the USPTO exam and building the AT-1!
 
I did many of the bolt in mods that WA6VVL applied to his AT-1 including the prolific use of terminal strips to reduce the wiring "load" on the tube sockets. Also, I increased the value of the filter caps. The orginal used 8ufd elects at 450 VDC. Dave used 33 ufd filters. I bought 47 ufd electrolytic caps. I suspect I won't have to much problems with AC on the B+ lines, eh? 
 
I also installed a new slide switch in place of the old AC power slide switch. Everything bolts into place except that the shaft of the switch is twice as long as the old switch. No matter. That was my intent. Note that the AT-1 does NOT have a pilot lamp installed. Other than looking through the cabinet grill, how can you tell that the transmitter is lit off other than keying the xmtr? I personally like the idea of looking at a pilot lamp...but NOT at the cost of drilling through an original panel. So, I reduced the projection of the switch's shaft by using a couple of 6/32 nuts as spacers. That puts a space between the front of the switch and the front panel. There is a nearby bolt that  I can mount a 6.3VAC pilot lamp so that when I turn on the AT-1, light will shine through the power switch space! I love doing no holes bolt on mods!
 
Anyways, I eventually put all the tube sockets on the chassis save for the one that allows the AT-1 to be place modulated. An error on my part as I miscounted the number of octal sockets used on the AT-1. It uses, five, not four octals! No matter. It will be coming in a bunch of other stuff shortly!
 
In the meantime, I did some of the preliminary wiring of the xmtr out of the way. The filtering system is in along with four (not two) 47K, 3 watt bleeder/equalizers. Just two leads will come off the terminal strips to the 5U4 so it won't look like a crowded mess. 
 
Finally. I'm cathode keying everything and I want to reduce the amount of chirp in the AT-1. VVL says he put his AT-1 on 40 meters with a CW xtal and tuned the "chirp" using a 3-30 pf padder on the 6AG7 Colpitts divider. The padder replaces the 15 pf cap used in the voltage divider chain just after the xtal. Say, does anyone have such a padder/trim cap in that range they can spare???
 
In any event, I'll keep you apprised of the situation. Seems like this listserv needs a little "resto articles" for a change. 
 
Cal, N6KYR. 


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