[Hammarlund] aligning my HQ-180

Sun Jul 27 14:59:39 EDT 2014

Thanks for all of the advise. Just what Im looking for. In response to a 
couple of comments that the Lower IF may not need to be adjusted.The 
reason I think I need to do it. I have watched a number of You Tube 
videos by Pete-K7PP. Dont know if any of you know the guy or are 
famalier with his videos, but, he has a numberof them with alignment and 
troubleshooting items for the Hammarlund 170's and 180's. He looks to be 
a Hammarlund buff for sure.But, my reason for thinking I need to realign 
the Lower IF is because he actually has a quick video test to show how 
one can tell whether or not your radio needs to be aligned in the 60kc 
IF. Without going into a lot of detail, I tried that test on the 180 and 
it showed the need for the alignment. Now, Im not going to say K7PP 
knows all, but, I think anyone who has watched his videos woulfd have to 
agree with me that he certainly knows what he is talking about. Anyone 
who has not seen any of his videos, here is a link to the one I am 
referring to. Even if everyone decides I dont need to align this low IF, 
Im gong to do it anyway because Im a tuning freak. I always want to make 
it a little better or make sure it is right on spec as close as an old 
radio can get. If I dont, I wont be able to sleep thinking "I shuda done 
that". HI. And Bob-KB8TQ hit the nail right on the head, "So Much Fun". 
Indeed it is!!

http://www.youtube.com/watch?v=4l1hWNvPe2g

Thanks-Bob-W0YBS

On 7/27/2014 12:25 PM, Bob Camp wrote:
> Hi
>
> Just to be clear - my focus was on the 455 Kc alignment rather than the 60 Kc. I’ve never seen a need to tweak the 60 Kc alignment unless a part was replaced.
>
> —————
>
> Signal level wise - one very good way to design a radio is to keep the gain low right up to the IF strip. The IMD and selectivity performance of the radio is improved by doing this. That was common knowledge when these radios were designed. Because of this, it’s not uncommon to run into IF decks with microvolt(s) level sensitivity.  I can’t say I ever measured the IF sensitivity of a HQ170 or HQ 170. I have no idea if Hammarlund went this way with the design.
>
> So much fun !
>
> Bob
> KB8TQ
>
> On Jul 27, 2014, at 2:03 PM, Roy Morgan <k1lky68 at gmail.com> wrote:
>
>> On Jul 27, 2014, at 10:17 AM, Al Parker <anchor at ec.rr.com> wrote:
>>
>>> Hi Bo, Bob, et al,
>>> 	There are "improved alignment notes for the HQ-170 -180’s
>> at:
>>> http://www.hammarlund.info/download/HQ170_180alignment.pdf
>>> 	There's also some factory svc notes for them on the "service" page.
>> I think that is here:
>> http://www.hammarlund.info/download/HQ170SVC.txt
>>
>> I offer some suggestions and comments that may be helpful:
>>
>> First, the 60 kc IF section of the HQ 170 may well not *need* any adjustment.  If the radio is working at all, the low IF may well be still in good alignment after all these years. Yes, I know that making sure it is right is a neat thing to do, and checking the alignment is very much in keeping with the wisdom from Ratty (modified to the realm of boat anchors):
>>
>> "There is nothing -- absolutely nothing -- half so much
>> worth doing as simply messing about …”   with neat old radios.
>> Ratty, to Mole
>> (from from Kenneth Grahame's classic The Wind in the Willows)
>>
>>> On 7/27/2014 9:32 AM, Bob Camp wrote:
>>>> You will have two problems with the 204. It’s not really very stable,
>> I suspect that the (frequency) stability problem will not be a big problem, especially if you follow Bob’s suggestion about a good warm-up period.  (You cold even leave it on overnight.) If it does turn out to be a problem try this:
>>
>> - To set the HP 204 frequency accurately, see if the AM-broadcast-band harmonics of the generator are strong enough to be heard on an AM broadcast band receiver.  If there is a station you can hear at any of the harmonics of 60 kc, (600 kc, 660 kc, and so on), you can adjust the generator to 60 kc with plenty of accuracy and detect any drift.  Couple the generator output loosely to the AM band receiver tuned to an AM station, even a very weak one, and tune the generator around 60 kc till you hear the thing beat with the station carrier.   A small pencil mark on the generator dial or index pointer will get you back there another day with out trying to re-calibrate the generator frequency dial.  You can listen to the beat note for a while to detect any drift of the generator.  Broadcast band transmitter frequency accuracy and stability are both way more than you need for this purpose.
>>
>> If you can’t hear any harmonics, try a resistor (a few hundred ohms) in series with most any diode to ground at the generator output - couple the signal from the top of the diode to the receiver.  I suspect that the diode will generate enough harmonics to be heard.
>>
>>>> ... it does not have an RF tight enclosure or attenuator.
>> This can be a problem with RF signal generators when you are trying to measure (or make a guess at)* RF input sensitivity of a receiver in the region of a few microvolts or below.  The level of signal needed for alignment of the lHQ-180 60 KC if strip is likely way above this, and the goal is to adjust the tuned circuits to the IF frequency, not measure or estimate sensitivity.
>>
>>>> To answer your question,
>> (about the 600 and 50 ohm termination impedance)
>>>> slap a 50 ohm load on the generator and a 20 db coaxial attenuator if you need a 50 ohm source. My *guess* is that you won’t see any benefit from doing that.
>> I agree there’ll be very little benefit. All we need to align the 60 KC section of the receiver is a voltage at a grid low enough to no overload the following IF amplifier.   I do suggest a DC blocking capacitor to avoid shorting out any B+ or AVC voltages.  At 60 KC, coax attenuators are not needed - an attenuator made up of fixed resistors would work find if you find you need one.  (Do NOT worry about inductance of modern film resistors at these frequencies!)  Do be careful to keep injected signal level low enough to avoid overload in the following stages - the manual procedure mentions this in keeping the DC detector voltage at about minus 5 volts.  I would expect the HP 204 attenuator to reduce the output to a low enough level to make a proper signal level for input to the 60 kc IF strip input, but a simple attenuator might well be needed.
>>
>> I read the alignment procedure and service notes at the links above, and saw nothing about the 60 kc if alignment process.  The document HQ170_180alignment.pdf seems to pick up after the manual procedure for the 60 kc alignment  and adds info on the 455 kc alignment  (my manual is the HQ-180A manual “Issue No, 3” in DJVU format presumably from BAMA).  After (or even before) you do the 60 kc alignment procedure, which is pretty simple, you can learn a lot about your low IF strip performance by using the signal generator.  The HP 204 dial will give you useful frequency and bandwidth information, even if it is not totally accurate as to frequency calibration.
>>
>> Do carry on - it’s satisfying to carry out a complete alignment with plenty of good test equipment and accessories.  It’s even more satisfying to make a good job of it with not-ideal equipment and a few other bits found in the Junque Boxe.
>>
>> As always, comments, corrections and other suggestions welcome.
>>
>> Roy
>>
>> *We have seen reports of the sensitivity of R-390A’s “measured” at levels below a half a microvolt and reported with three significant digits.  In my opinion this is total baloney.  The below a half microvolt part is difficult to achieve, though with care and good equipment is possible at home.  The three digit part of RF voltage measurement is virtually impossible for us common folks.  It is possible by NIST RF measurements people, but it involves a big fee, a lab full of carefully developed equipment, many decades of experience, and a PhD electrical engineer who specializes in such calibrations.
>>
>>
>> Roy Morgan
>> RoyMorgan at alum.mit.edu
>> K1LKY Since 1958
>>
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