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   Home   Help Search  
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Author Topic: Hammarlund HQ-170 help needed.  (Read 5778 times)
AJ4CU
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Posts: 78




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« Reply #15 on: October 20, 2011, 01:15:50 PM »

Well,

Things have taken a turn for the worst, my LG-1 has no output all I get is 60Hz on my sencore so I am guessing the can electrolytic has failed, I ordered a full set of caps to re cap it, in the mean time tested the tubes -ok- and when re capping will check all resistors, I will also take this opportunity to install a bnc connector on the front panel, so for the time being I am dead in the water unless there is some way I can use the T-4 Signal tracer (like I said I am not that familiar with using this) to improvise?

Suggestions?

Again Thanks,
AJ4CU
Hari
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W5RKL
Member

Posts: 894




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« Reply #16 on: October 20, 2011, 02:19:22 PM »

Since the initial test, powering up the 170, produced static in the speaker then that indicates the audio amplifier is working. This does not test the detector, BFO, and other stages leading to
the front end of the receiver. However, to be sure all audio stages are working, you can use your audio signal generator and inject a low level audio signal to pin 1 of V16 (first audio stage).
You should hear the audio generator's signal in the speaker.

I agree, since you have a frequency counter and until you fix your LG-1 signal generator, you can at least test the BFO oscillator output to see if it's working. Connect the frequency counter
to pin 7 of V9, turn the BFO ON then rotate the Pitch control. The frequency counter should display the BFO oscillator's frequency and the frequency should vary up or down depending on
which direction you adjust the Pitch control.

I also recommend measuring each tube socket voltage then compare the measurements against the voltage chart on page 19 of the 170 manual. A missing voltage, for example, at a tube socket
pin can easily point you towards the source of the receiver's problem. You will need the 170 manual and study the schematic to locate the source of the missing voltage. You don't need a
signal generator to measure the voltages at each tube socket pin. A DVM or VTVM will work.

73s
Mike



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G3RZP
Member

Posts: 4830




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« Reply #17 on: October 21, 2011, 03:12:48 AM »

Murphy says that if you need a piece of test gear to repair something and you have that test gear, it will need fixing before you can get any further.

I am somewhat pleased to find it isn't just me that it happens to.....
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AJ4CU
Member

Posts: 78




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« Reply #18 on: January 16, 2012, 05:57:16 AM »

The HQ-170 is working!

Issues found = cruddy tube pins/sockets, cold solder joint...

Repaired joint, cleaned pins/sockets with deoxit, checked alignment, radio is working great!

Thanks for the assistance, oh and I have rebuilt all my older test gear to fully operational status!

73 DE AJ4CU
Hari
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G3RZP
Member

Posts: 4830




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« Reply #19 on: January 16, 2012, 06:44:00 AM »

Well done Hari. Congratulations.
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