[Hallicrafters] SX28 progress

[Guido]

I have finally dipped into my sx28 to solve some sensitivity and feedback
issues and here are soem of my observations.

   - I found most of the mica caps in the HF Osc area bad. Tested them with
a Sprague Cap tester.
  - Replaced most of the mica  caps in the set including C61 inside T1.
  - Replaced quite a bunch of really out of spec resistors many in the 500k
range.
 -  Performed a "by the book" alignment of the set.

Results:

  - Greatly improved sensitivity and solution to most of the feedback
problem except in the lower frequency sections of band 5 and 6.
  - Apparently some of the ceramic caps used across the RF section may have
changed values. In band 4 the RF tuning coil for the lower side of the band
tunes almost at the very end of the screw. On bands 5 and 6 it is difficult
to have the correct tracking at the lower and upper end of the band and this
seems to produce the feedback that dissapeared from band 4 after adequate
adjustmets of the upper and lower ends of the bands.

Question: What values of voltages are read during the adjustment of the ANL
and AVC ? When adjusting T5 the DC voltages that I read where very low and
changed little. Adjustment of T6 did produce a peak voltage though.

On the adjustment of the crystal selectivity using the upper slug in T2 they
call for an adjustment in the middle of the two highest values that you
obtain by rocking the frequency generator a bit. Is this a correct
interpretation of this adjustment?

Thanks to all who have been helping out. I think that I am almost there.

73s
Guido KP4FAR