Hi all,
New member here and recently retired, have been a ham since 1967 and started to fix/refurb old ham radio equipment in my leisure time now.
So far successful with some old receivers..Knight Kit Star Roamer, Heathkit 303 and most recently a Hammarlund HQ-100A.
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So now I decided to try a transmitter to go along with the HQ-100A and picked up a beautiful Hallicrafters HT-40 Mark 1 in great physical condition but known problem.....only can get 2 watts out. I thought this would be a great project but now I'm not so sure. I think I'm reaching the point where I could use some help.
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I've attached the schematic I've been working from that closely matches my rig. When I received it I brought it up slowly on a variac and sure enough.,.Only 2 watts out.
I figured I'd do the basics since it appears all original...I replaced all electrolytics and any HV paper caps,? also replaced any resistors or caps that were more than 10% off, (except all disc ceramics) and cleaned all switch contacts.
Fired it up again...only 2 watts out.
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Long story short... I replaced each tube individually and then tried all new tubes..... still 2 watts out.
The biggest issues are.
1) cannot get any grid drive in tune position
2) I have only -5 vdc to +1.0 vdc on the Grid of the final V2 depending on position of Drive cap instead of -50vdc according to schematic.
3) Again, the Final V2 Pin 4 and 8 should have 130vdc in CW and 30vdc in AM. I have 26vdc in CW and 12 vdc in AM??
4) Tube V1 Pin 8 should have 210vdc but I'm getting 350vdc and I've replaced R3, R6 and R7.
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I've resoldered almost all connections, wiggled each tube socket terminal during transmit...nothing changes.
The only thing I found different was L2 is a 5uh choke instead of 100uh, don't know if this was a modification or mistake. I put a 100 uh in its place....still 2 watts out.
I'm really stuck at this point and tested most components except the .001 and .005 ceramic disc caps, any of those I did pull and tested were good.
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I'm hoping someone could lead me in the proper direction.
Thanks,
Larry
WA2DGD
