[Hallicrafters] SX-100 Lower SideBand Problem

[wb8jkr at juno.com]

 Bad crystal socket?

Mark  WB8JKR


On Sun, 5 Dec 2004 07:12:54 -0700 "DW Holtman" <future212 at comcast.net>
writes:
> I'm in the middle of trying to get my SX-100 working. I have the 
> following problem.
> 
> UpperSidtband (USB) works great, LSB will not work at all. The LSB 
> (1600 khZ) will not oscillate.
> 
> I did the following with no clue why it does not work. 
> 
> 1. Removed the Sub-chassis and connected it with jumpers so it will 
> operate next to the radio, so I can trouble shoot it. 
> 
> 2. Switched crystals, both crystals oscillate in the USB slot and 
> neither oscillates in the LSB slot. 
> 
> 3. Measured voltages and resistors on the stage, (12AT7) everything 
> checks normally. 
> 
> 4. Measured the inductance of the top and bottom of T9 (. They both 
> adjust from about 20 to 50 uH. The USB crystal (bottom) turns on 
> around 33 uH, adjusted the LSB (top) for the same, will not 
> oscillate. Tried to adjust the top (LSB) many times and the stage 
> will not oscillate. 
> 
> 5. Swapped tubes twice and tested on a tube tester. 
> 
> 6. It is getting its ground from the "Response" control switch 
> (Green Wire). 
> 
> 7. The only difference that I can find is the capacitance from the 
> Cathodes of the oscillators (Dual Triodes) . USB reads .009 uF to 
> ground; the non-working LSB reads .007uF. I don't think this would 
> not allow it to oscillate. 
> 
> I'm running out of ideas. Any suggestions would be greatly 
> appreciated. 
> 
> Thank you, 
> 
> DW Holtman 
> 
> WB7SSN
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