Aligning Heathkit HW-101 Receiver

[nocusr]

Can't get the VFO to track properly on receive. Following the manual-adjust VFO coil at 4 MHZ, VFO trimmer caps at 3.5 MHZ, either the dial reads 15-20 KHZ high at the low end of the dial (with the high end right on), or 15-20 KHZ low at the high end (with the low end right on. It's like the dial is too long! Did all the preceding adjustments: heterodyne oscillator coils, transformers, slipping the dial. Even tried aligning it with an external RF generator. I bought this used and am attempting to restore it. The construction is superb, it's in immaculate shape, and the transmitter works. Thanks

 

[zz0468]

Typically in that sort of alignment, you can expect to have to go back and forth several times before it tracks linearly with the dial. If it gets worse at each pass, try reversing the order of the coil and capacitor adjustments on the low and high frequencies and see if that starts getting it closer.

If it's not getting closer with each pass, start looking for bad capacitors in the vfo.That could mean pulling each and every capacitor and checking it thoroughly out of the circuit. You may also try aligning to 0 and 400 KHz on the dial, and let 500 KHz end up where it may. HW-101 VFO tracking was always less than perfect. A lot of builders gave up at 400 KHz, and relied on the calibrator to tell them where the upper band edge was.

 

[nocusr]

Problem solved!

Thanks for your response. I went back and forth so many times, my wrist started to hurt! Anyway, the problem is fixed. I found a Heathkit bulletin (#45 16 Feb 1979) referencing this problem. The solution was to use the lower of 2 peaks while adjusting the VFO coil - would of been nice if this was mentioned in the alignment procedure. The calibration now is as perfect as it could be for an analog tuning dial.