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I have a mid-era Hammarlund HQ-129-x. It sounds great if I don't count the motorboating. But the problem is in the middle bands. I got the radio way out of alignment, and managed (I think) to get the IF working.

I receive strong stations (folded, loaded, irregular-dipole) okay, no images. Even the blasting AM station on 1450 sounds great, so long as I throttle way back on the sensitivity control. I only hear it on 1450, so the selectivity is good. No images!

But the weirdest part is: I get WWV interference across the bands, all six, but it's the middle four that gets it the most. I can pick up the WWV signal when it's clear, and it interferes with itself. I could understand if 1450 were the noisy cricket, but... WWV?

How can I snuff out WWV from wherever it's not supposed to be?

Caoimhin

Caoimhin
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    What do you mean by "I can pick up the WWV signal when it's clear, and it interferes with itself." When what's clear? And what does "interferes with itself" mean specifically? – Phil Frost - W8II Dec 28 '20 at 04:43
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    You will need a RF signal generator (50 kHz to 20 MHz) to find unwanted spurious reception spots of your receiver. Something must be wrong in the input circuit of your receiver. Or do you live within a few miles from the WWV transmitter? –  Dec 28 '20 at 18:03
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    Hello and welcome to ham.stackexchange.com! – rclocher3 Dec 28 '20 at 22:59
  • Thanks, I hope this new hobby evolves! – Caoimhin Dec 30 '20 at 02:05
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    When conditions are right, I can hear the WWV clearly, and as the ionosphere fluctuates, WWV is heard, but with a serious buzz. I can sometimes hear this on the WWV signal, and the station itself can't be heard. No dial change.

    I'm in Rhode Island, a few time zones away from Colorado. I live just a few miles away from a full power AM station. I only hear the AM station on its true dial position, and I have to throttle back all the way on the sensitivity control and it will sound great, save for motorboat.

     – Caoimhin Dec 30 '20 at 02:11
  • I can sometimes chase the interference with the bandspread control, following in its wake in quiet radio noise. I can hear hundreds of faint stations that don't get detected all the time, their AM whistle gives them away. – Caoimhin Dec 30 '20 at 02:16
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    You need to check the receiver with a RF signal generator. There is one theoretical mixing product from your information that needs also investigation. Two times 1450 kHz can lead to 2900 kHz in your receiver. And the IF of the Hammarlund is or was "... way out of alignment...". That 2900 minus 2500 (WWV). Almost impossible, but check the actual IF. Again: you need a signal generator. Succes –  Dec 30 '20 at 17:43
  • Motorboating is a symptom of a bad capacitor, usually an electrolytic plate bypass. A bad capacitor somewhere might be the cause of the hum you hear. – Mike Waters Dec 30 '20 at 21:20
  • A signal generator is on the way. Plate bypass caps are all ceramic disks. Would PET work significantly better to justify a re-cap? IF is .457kc, determined with crystal resonator oscillator and frequency counter. It makes a nice sine wave.

    This morning, I didn't hear any WWV interference, but last night it was on-off bad to horrible. It may be difficult to be certain if the interference is gone or not.

     – Caoimhin Dec 31 '20 at 22:50
  • When your signal generator is on your workbench then I am interested in your measurement results. With these results: please indicate what antenna type you are using and how it is connected to the three terminals of your receiver. In the manual there is an example for dipole connection and also for longwire-ground connection. PA0FSB –  Jan 02 '21 at 11:15
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    Antenna type: folded, random-loaded asymmetrical dipole apartment-type antenna, connected on the A terminals. Grounding the case, there's a few volts AC to the screw terminal on the house plug. It has no apparent effect, but ground-effect goes away when I put a 0.1uF cap in the wire to ground. I did play with the alignment again, and don't know what I did right, but the WWV interference is gone. The signal generator will improve things. I should de-tweak to bring back the WWV just to see what I did right! – Caoimhin Jan 04 '21 at 14:27
  • Succes. When you have additional questions then you can reach me via email or Facebook. –  Jan 04 '21 at 15:38
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    It appears that this worked for you, so please post that comment as an answer and mark it accepted. Otherwise, the system will keep bringing this to the top. – Mike Waters Jan 04 '21 at 21:11
  • Nothing is solved, Mike. The antenna connectors on the Hammarlund are confusing; the added cap to ground has a good chance as solution: the power supply line can cause the mentioned interference because it is functioning as antenna. The decoupling capacitor removes this unwanted antenna signal. Caoimhin can comment on this. And I can't give this as an answer. –  Jan 04 '21 at 22:01
  • Power line grounded through cap didn't solve the interference. There are three antenna terminals, A, A, and G. The two A terminals are 400 ohm balanced, they work with twinlead. Some people ground the A that's closest to the G, but I lose stations like that. No success yet, it was my monkeying blind with the IF transformers that got rid of the WWV interference. The signal generator just arrived today. It works, and I'm just waiting for some ibuprofen to start working. 43 pounds of awkward isn't good for the back! What was I thinking when I bought this boat anchor? – Caoimhin Jan 06 '21 at 23:43
  • Alignment worked: 15MHz WWV came in at about a half a line higher than its actual frequency. No more WWV interference. A few more stations, and they're all clearer. I won't need to move it again for over a month, I'm happy with this rough alignment. Thanks for the help! I just wish they'd made those boat anchors out of aluminum, instead of discarded engine blocks. – Caoimhin Jan 09 '21 at 03:15
  • Nice result, well done. Have fun with that old stuff! –  Jan 09 '21 at 11:46
  • Thanks! I also learned out how to get that WWV interference back, and get rid of it. The lower screw on T2 in the crystal filter has two loud spots. Use the high side just as the volume falls off between the peaks, and tune up from there. – Caoimhin Jan 13 '21 at 19:20

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If you were messing with the alignment, it's possible that you have inadvertently switched the local oscillator from high side to low side injection. Or vice versa. Hence all the unwanted images. Rule number one for boat anchors (from personal experience) is "don't mess with the alignment." Unless you know what you're doing, chances are things will get worse. At this point, make sure you have a proper service manual for the radio and that you go through the entire procedure to the letter.

Violin_Teacher
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