HQ-170 Alignment Question

[K2AWA]

I'm somewhat new to the old receivers and trying to understand the inner workings.

For the most part I'm happy with the receivers performance and sound, but not with the dial frequency settings on 80m. The calibration is way off the mark with regard to the dial settings. Included is a picture of the dial where it receives 3.826.00, so I actually hit the end of adjustment before the end of the 80m band. The calibration is pretty good for both 40 and 20 meters though.

To me, that doesn't seem like a dial issue, so will an HF Oscillator adjustment remedy this situation for 80 meters? I certainly don't have the experience or equipment to perform this, but a ham I know has all that's needed. He has never tuned a boat anchor, but he said it shouldn't be too bad with a manual, which I downloaded.

Any guidance would be appreciated!

Thanks! 

[Pete, WA2CWA]

Doing an RF/frequency alignment is not a complicated process if you follow and understand the steps given in the alignment procedure. However, given the vast range that the dial calibration is off on 80 meters, I might suspect you may have some component issues that are unique to the 80 meter band.

[KB2WIG]

G,

What happens when you move that unmarked knob, the one next to your "Slot Depth"?

klc

[aa5wg]

K2AWA,

Here is a youtube link for alignment help regarding Hammarlund radios.

https://www.youtube.com/user/dogtagsvette

K7PP, Pete, is the gentleman in the link.

Good luck.

73,
Chuck

[K2AWA]

G,

What happens when you move that unmarked knob, the one next to your "Slot Depth"?

klc

That knob only moves the marker.

[WA2SQQ]

I realigned my HQ-180 and found that the majority of the dial error was corrected by doing the mechanical alignment. I did find two caps that had to be replaced, one of which was a trimmer. K7PP's videos really helped me get through it without too much frustration.

I also found that some oxidized contacts on the band switch caused some instability. Be very careful if you use Deoxit on those wafer switches. The phoenelic material absorbs it and swells, making the switch operate very tight. Apply it directly to each contact with a small artist brush.

In case you find any bad parts, I have a fairly complete HQ-180 chassis that may have some common parts. I've been piecing it out to those who are restoring them.

[KA2DZT]

Doing an RF/frequency alignment is not a complicated process if you follow and understand the steps given in the alignment procedure. However, given the vast range that the dial calibration is off on 80 meters, I might suspect you may have some component issues that are unique to the 80 meter band.

I agree, dial is too far off the mark,  some component is off somewhere in the 80 meter osc coil circuit.  How far off is the dial at the low end of the band??

If the dial is a lot closer to correct readings at the low end the problem is most likely the osc trimmer cap.  The osc coil will have the greatest affect at the low end.  Your problem indicates too much capacitance or too much osc coil inductance.

Fred

[K2AWA]

Went and checked one end of the band and then the other as Fred mentioned. Calibrated with my HT-37 and verified each end with my frequency counter. The low end shows where the receiver ends up when transmitting at 3.6 and then the upper setting when transmitting at 3.8. Obviously a larger separation at the high end.

So, we are thinking a bad component? Any experts(that have done this) willing to give me a hint on the schematic designation from the HQ-170 parts list?

[Pete, WA2CWA]

Went and checked one end of the band and then the other as Fred mentioned. Calibrated with my HT-37 and verified each end with my frequency counter. The low end shows where the receiver ends up when transmitting at 3.6 and then the upper setting when transmitting at 3.8. Obviously a larger separation at the high end.

So, we are thinking a bad component? Any experts(that have done this) willing to give me a hint on the schematic designation from the HQ-170 parts list?

Not necessarily. The simplest thing to do would be to see if you move the alignment close to where you want it. You can use the HT-37 as the generator. As before, set it to 3.6 MHz, set the receiver dial to 3.6, and adjust the RF oscillator coil to see if you can get it there. Here's the tricky part. The oscillator coil housing of interest has two coils; one for 1.8 MHz and one for 3.5 MHz. See page 11 of manual. The 3.5 MHz coil is the lower one. Your alignment tool end has to go through the top coil slug and only into the bottom slug. Then set the HT-37 to 3.9 MHz and the HQ-170 dial to 3.9 MHz and adjust the 4 MHz trimmer on the underside of the chassis. See page 12. If you can get those two frequencies roughly where you want them to be, most likely there isn't a component problem. I wouldn't diddle with any components in this area until you can verify it really is a component issue. Checking the tubes, checking the voltages and resistances (you have two charts to do this from) should be done first before proceeding with a full and careful alignment.

[KA2DZT]

You need to adjust the 80M osc coil to bring the low end into calibration.  The fact that too much inductance affects the low end to a lesser degree as far as reducing the capacitance (there is more capacitance per degree of movement at the low end), therefore the dial needs to move up to lessen the amount of capacitance a certain amount.  Now, at the upper end,  the tuning cap has a much less amount of capacitance per degree of movement.  Therefore, you must move the dial up band a greater amount, than at the low end, to bring the dial into calibration.

I would try adjusting the osc coil.

Fred

[K2AWA]

Thanks for the info....I'll give it a shot.

Glenn