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Author Topic: Hammarlund HQ-170 help needed.  (Read 5907 times)
AJ4CU
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Posts: 78




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« on: October 17, 2011, 06:55:16 AM »

Greetings all,

Well I have mostly been playing with Hallicrafters radios and recently in a bunch of gear I purchased there was this Hammarlund HQ-170, sadly it was disassembled (just the faceplate and all attaching components and tubes removed) I re-assembled the radio, tested the tubes -ok-, did an extensive visual chassis check and slowly powered it up with a variac, all good so far, brought to 117Vac no pops or cracks, let it sit for a couple hours -ok-.
Next I connected a 4ohm speaker (I have no 3.2 ones) and a long wire antenna I have in my attic, nothing but static, nothing as I sweep through the bands, all bands..., no s-meter movement at all, in fact, the s-meter does what I would initially expect it to do, on power up it goes full swing then returns down but instead of sitting on "0" it is being pegged to the negative side of the meter, of course when I place the radio in transmit is settles to "0", going into calibrate there is no tone anywhere, my skills are limited so I thought I would ask here to see if anyone could offer some advise.
This radio is in really great condition (except for not really working) and it would be nice if I could get it working.
Thanks in advance for any and all assistance.

73 DE AJ4CU
Hari
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W5RKL
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Posts: 896




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« Reply #1 on: October 17, 2011, 07:04:27 AM »

There is an "S meter zero" control on the rear panel. Adjust that control to zero the meter pointer with no antenna connected.

Do you have the manual for the HQ-170? If not then I recommend you download the manual:

http://bama.edebris.com/manuals/hammarlu/hq170/

and follow the alignment procedures in the manual.

The manual may be in "djvu" format which requires the djvu reader. The reader is available for free
at the following website.

http://windjview.sourceforge.net/


73s
Mike
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AJ4CU
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Posts: 78




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« Reply #2 on: October 17, 2011, 07:21:41 AM »

Mike,

S-Meter controls have no affect on the meter needle, as for alignment, all paint dabs on trimmers ect... are intact so before attempting that if the radio was able to receive should there be at least some changes in the bands and tuning through them? right now the noise from the speaker is steady and no changes at all through any band...

Any other ideas?
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W5RKL
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Posts: 896




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« Reply #3 on: October 17, 2011, 02:50:13 PM »

Have you tried listening for the calibrator signal at 100Khz intervals on the dial?

73s
Mike
W5RKL
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AJ4CU
Member

Posts: 78




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« Reply #4 on: October 17, 2011, 03:03:58 PM »

Mike,

Yes, on my original post I stated that I could hear no calibrate tone anywhere on any band, I performed this per the manual of course.

Thanks, anything else??

AJ4CU
Hari
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G3RZP
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Posts: 4954




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« Reply #5 on: October 18, 2011, 03:22:47 AM »

Is there a difference in noise between AM and SSB/CW? If so, does varying the BFO change the pitch of the noise? Is there a change in the pitch of the noise when switching between USB and LSB?

These tests will tell you to what extent the IF chain is performing. You need a signal generator to feed in a signal, firstly at the 50 (or is it  60) kHz final IF. Then at the 455, and finally at the 3035. Working backwards from the detector will enable you to isolate the problem.
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W5RKL
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Posts: 896




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« Reply #6 on: October 18, 2011, 06:47:39 AM »

Hari,

The HQ-170 is a triple conversion receiver (dual conversion on 160 and 80 meters, triple conversion on 40 and above).

The IF frequencies are 3035Khz, 455Khz, and 60Khz. This is all explained in the 170 manual starting on page 8.

Do you have a signal generator, VTVM, and possibly a frequency counter? If not then you will have to obtain them to
troubleshoot the 170's problem. The signal generator must be capable of producing an RF signal at 60Khz to test the
60Khz IF stage. Many inexpensive signal generators do not go that low, most only go as low as 100Khz.


73s
Mike


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G3RZP
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Posts: 4954




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« Reply #7 on: October 18, 2011, 07:09:55 AM »

Some AF and function generators go up to 60kHz, though. Although the output isn't controllable to very low levels, it can be enough to start with.
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AC5UP
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Posts: 3955




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« Reply #8 on: October 18, 2011, 07:15:49 AM »

Just for grins I looked up the bandwidth spec on the venerable AN/URM-25D.............. 10 KC's to 50 MC's.

..............which means I'll probably hang on to mine forever, if only to piss of dogs.  Grin
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W5RKL
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Posts: 896




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« Reply #9 on: October 18, 2011, 08:41:08 AM »

If Hari doesn't own, or have access to, a signal generator that will go as low as 60Khz, he could start at the 455Khz IF stage and work his way to the receiver's front end.
This only works as long as there are no problems in the signal path of both 455Khz and 60Khz IF stages.

73s
Mike
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AJ4CU
Member

Posts: 78




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« Reply #10 on: October 18, 2011, 10:27:53 PM »

Thanks for the replies!

There is no change in audio output at all between am/ssb,cw and the bfo makes no changes either.

The test gear I have for this type of work is a Heathkit LG-1 signal generator, Heathkit V-7a VTVM, Heathkit IG-5280 RF Oscillator, and a solid state Signal Generator by ECI that is .2 to 6.0 mHz.

Suggestions?

Thanks for the input thus far guys...
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G3RZP
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Posts: 4954




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« Reply #11 on: October 19, 2011, 02:55:04 AM »

Feed some 1kHz audio in at the AF gain control, see if there's AF. If so, switch to AM, feed 60kHz modulated in at the 6BN8 AM detector plate. If there's output, feed 60 kHz in at the plate of the 6BE6 mixer from 455 to 60 - using a blocking cap. If you still have AF, switch to CW and see if there's a heterodyne whistle. If there isn't check around the BFO with the VTVM and an RF probe - If you don't have one, make one.

Use a 10pF capacitor from the input, then a small signal diode to ground, and a 4.7Meg or so resistor from the capacitor-diode junction to the VTVM.

An oscilloscope woul be handy here.
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W5RKL
Member

Posts: 896




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« Reply #12 on: October 19, 2011, 07:37:04 AM »

The IG-5280 is an audio oscillator with a frequency range from 10Hz to 100Khz.

The LG-1 is an RF signal generator that would work to feed the 455Khz IF stage. It appears to have a built-in audio oscillator that will modulate the generator's RF output signal.
The IG-5280 can also feed an audio signal to the LG-1's external audio input so you can vary the audio frequency that modulates the LG-1 RF output signal.

If you use the LG-1 signal generator I recommend using a frequency counter to set the generator's output frequency to 455Khz. The LG-1 will drift and you want the LG-1 signal
to remain at 455Khz, not drift above or below.

The purpose of the following test is not to align the 170 but rather to simply find out whether the 455Khz, 60Khz, detector, BFO and audio amplifier are working, nothing more. Keep
the LG-1 output signal low at first. If you have a few small alligator clips, connect the LG-1 to the circuit through a .01ufd disc capacitor with a voltage rating of 50VDC or higher.
This will prevent any voltage from the 170 being applied to the LG-1 signal generator and vice verse.

Tune the LG-1 to 455Khz (use a frequency counter to ensure the LG-1 output frequency is set at 455Khz) then connect the LG-1 to the 170 first IF amplifier, V4 pin 1. Turn the LG-1's
internal audio oscillator ON. Power up the 170 and if the 455Khz and 60Khz IF stages along with the detector and audio amplifier are working, you should hear the LG-1's audio oscillator
signal in the 170's speaker. You should also see the S meter rise above zero. maybe peg full scale to the right. If the meter pegs full scale to the right, lower the LG-1's output signal level
until the S meter rest around mid scale. You can also adjust the Sensitivity control to lower V4's gain. If the LG-1 RF signal changes frequencies when reducing RF output, adjust the generator
so the signal remains at 455Khz. Turn the 170's BFO switch ON and turn the LG-1's audio oscillator OFF. You should hear a beat note in the speaker if the BFO oscillator is working.

73s
Mike





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AJ4CU
Member

Posts: 78




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« Reply #13 on: October 19, 2011, 08:41:38 AM »

Mike (W5RKL) and G3RZP,

Thank You,
I am not sure I understand what G3 is telling me it seems I do not have a tool to do the frequency I need to perform that test, so,
Later today I will perform the test the Mike (W5RKL) is suggesting and let you know the outcome, I also recently purchased a Heathkit T-4 Signal Tracer, although having never used one would this help in troubleshooting this radio?
Also at this time I have no manual for the IG-5280 so I am not familiar with it's operation, I have been trying to find one with no luck.

As for Frequency counters to adjust the LG-1 that is not a problem, I have a Sencore FC-51 and a BK Precision 1823 counter, I also have plenty of disc caps.

I will post later today,

Thanks fellas,

AJ4CU
Hari
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G3RZP
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Posts: 4954




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« Reply #14 on: October 19, 2011, 08:52:15 AM »

Start by checking that the AF stages work.

Then the BFO - you should be able to measure that with the counter and a probe.

Whentrouble shooting a receievr, start at the back, the output, and work your way forward to the antenna. That way, you find the bad stage or stages.....
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