SX-25 AC line voltage ????

[W2JBL]

cough, retch, gurgle, puke....

[w8pu]

Carl / Rodger
   I have always had an issue with dial calibration and tracking across the band. I realize that because of the age of the receiver it will never be really great across any range, but I did improve it greatly by repositioning the mail dial ( except band 4 ). I had the receiver apart to clean it up initially, and I beleive I put the dials back in their original positions, but now I am suspicious of the main dial. Each of the trimmers for the convertor and 2nd RF stage seem to have a sweet spot where, regardless of the exact dial position, they have a definate peak. When trying to adjust them to match the dial with a signal generator to the given alignment frequencies per the manual the sensitivty drops off. By repositioning the main dial on the tuning capacitor shaft I have tried to match up the sweet spots with the proper frequency on the dial. Bottom line with the main tuning fully CCW, the capacitor sections meshed, my main dial lines up with 100 on the logging scale. Before it was just the opposite. I would appreciate your thoughts and how your SX-25's are set up with respect to the main dial.


73, Gary

[WQ9E]

Gary,

That is correct for the main tuning dial/cap.  The cap should be at full mesh with the dial set for 100.

The bandspread is the opposite, 100 is at minimum mesh and alignment should be done with the bandspread set at minimum mesh.

It is VERY easy to adjust the oscillator where it is tracking on the wrong side on these receivers.  I believe (double check the manual) that the oscillator should track on the high side (IF frequency PLUS dial frequency) on all bands but a few of the Halli receivers use low side tracking on the highest band.  The easiest way to make sure the oscillator is set on the correct side is to set the oscillator adjustments while listening to it in an external receiver; I keep a Grundig YB-400 on my bench which is perfect for this task.

On many receivers, including the SX-24 and SX-25, aligning the mixer will "pull" the oscillator and it is easier to make the mixer adjustment while listening to wideband noise rather than the signal generator on the higher frequency ranges.  Any broadband noise source (such as an appliance with a universal motor) will suffice if you don't have a test source providing broadband noise.  If you use the signal generator, you will simultaneously have to rock the tuning of it while making the mixer adjustments which is more difficult than using broadband noise.

[w8pu]

Rodger,
  My variable temp soldering iron is a great source for noise, good for checking noise blankers as well HI HI. What I had been using was the signal generator sweeping a 100 khz either side of the wanted output frequency. Anyway all is well now except band 4, everything is shifted off and I need to recheck I am on the right peak. Thanks again !!

73, Gary  W8PU