[HBR] HQ-160 Osc Issue

[Byron Tatum]

Hello-
  I apologize for the off-topic post, but I was hoping someone here may have a suggestion for me in trying to resolve an issue with an HQ-160 receiver. Here is the issue: The receiver has a bad "raspy" note when listening to CW, and a bad warbly raspy sound when copying SSB. The problem is much worse on 10 meters than on 40 meters.
 I suspected the tuning osc may be the culprit, since the problem worsens on the upper bands. So, I warmed up an R-390A and listened to the 3.49 MC xtal osc (used on two upper bands only) and it has a nice pure note. I listened  to the harmonic of the BFO (910 KC) and it has a nice pure note. Then, I listened to the tuning osc at around 31.9 MC (HQ-160 tuned to 10 meter band) and it sounds terrible in the R-390A. The tuning osc in HQ-160 is around 3.3 MC above the receive freq. When listening to the tuning osc on the R-390A it has the same raspy note that the HQ-160 does when receiving a 10 meter carrier. The tuning osc note gets much better as the HQ-160 is taken down into the lower bands. It is still objectionable on 20 meters,on 40 meters it is noticeable but not terribly irritating.
 I have done these things so far:
   1. Converted power supply to solid state and added another choke, making it a choke input with new electrolytics. Checked for ripple, is around 2.5 mV on regulated 105 VDC.
   2. The tube sockets are riveted in place, and soldered on one side. I resoldered all of them with a 300 watt Weller.
   3. I installed 0.01 uFD bypass caps on fil terminals of RF Amp, OSC and first mixer tube sockets.
   4. Cleaned all bandswitch contacts carefully, retightened all mounting and grounding screws on RF tuner assembly, and cleaned tuning caps contacts.
   5. Checked resistors in affected area to insure all in tolerance.
 After just about giving up I took a second HQ-160 that is still all-original (one that I am nearly through cleaning up) and listened to its tuning osc on 10 meters at 31.9 MC in the R-390A. Low and behold, it had the exact same raspy sound and the other HQ-160. 10 meter on-air signals sounded nearly the same too.
   So, I am starting to think that the HQ-160 has something inheritent in its design to cause the raspy tuning osc note? I got out an HQ-170 that I did a lot of things too a couple of years back and it sounds great on 10 meter SSB. When you look at the large massive coils and tuning capacitor assembly of the HQ-160 it appears to be of much better quality than the little canned coils of HQ-170. At least, that is my first take on it.
   Any suggestions appreciated,
                  Byron WA5THJ