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 Post subject: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 7:54 pm 
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Background:

1. The Hammarlund SP-600 JX-1 in question was recapped and RF deck completely rebuilt and aligned about 5 years ago. It is a great receiver that works very well. However, I now notice that it drifts in frequency. I am now compiling extensive statistics, but have these preliminary time and frequency stats:

Time Frequency (Hz)
10:20:00 AM 14,037,500
10:31:00 AM 14,064,300
11:06:00 AM 14,069,400
11:23:00 AM 14,058,200
11:30:00 AM 14,041,900

Question:

Is such drifting normal for this receiver?


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 8:09 pm 
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Yes these receivers do drift and some consider the problem extreme. I've never measured just how much my receiver drifts, but I use it on A.M. so I wouldn't notice it all that much.

It seems odd to me that it drifts up AND down, and especially such large swings in such short amounts of time. I'd think it would only drift in one direction. Has the receiver been in continual use for some time? You might also check to see if your B+ is OK/stable as other loads, HVAC, clothes drier cycle. and verify the VR tubes are lit.

I'd also suspect the Turret fingers and RF deck pincers might be dirty.

Image

Image

There will be others chime in with perhaps more knowledgeable assessments, soon, I suspect.

Good luck with your problem, and please report back when you find the cause.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 8:33 pm 
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The up and down was weird to me too. (By the way, the frequency is being read by a DD-101 digital readout that works with a shield slipped over the HF oscillator tube.)
The unit was cleaned thoroughly when rebuilt with an emphasis on contacts. However, I have three notes to add:

1. I used WD-40 on contacts and tube sockets when it was rebuilt about 5 years ago.
2. The unit has not been used for about 1 year.
3. The BFO would cutout after about 1.5 hours, but would often come back after toggling the CW-MOD switch. I pressed down on the 6C4 BFO oscillator and now it has been working for over 2.5 hours without cutting out. Let's see if it stays on for another few hours. Could the BFO issue be totally unrelated and caused by a tube socket having some residue WD-40 or dirt?

Could it be the 0A2 regulator going bad?

Thank you for responding with very helpful ideas and photos.

Just saw your galleries!!!! Awesome!!!!


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 8:50 pm 
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Check your voltage on the power supply transformer. It's probably on tap no. 4 which is 117 volts. Switch to tap no. 5 for 130 volts, that will help. And, if you have a spare OA2, replace just because it's lit means nothing. Those two items will usually cure SP-600 drifting problems.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 8:51 pm 
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The BFO and Drift are unrelated, unless, the B+ is unstable, in which case both could /would be affected. As for the counter, do you know the accuracy and stability of it?

I don't use much contact cleaner, but when I do, it's the Deoxit concentrate, whatever its called. Any liquid left on a mechanical connection is going to be what I consider a dust magnet. For what it's worth, I know some use WD-40 as a contact cleaner, and I've never researched the subject to come to any conclusion, but my first inclination would be not to use it.

In any event, since the radio has been setting for an extended period of time, I'd make it a point to at least vigorously exercise the band switch to clean off any accumulation of contaminants. If it's scratchy, it's dirty.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sat 29, 2018 8:53 pm 
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Hi Les,

What kind of drift "numbers" would be Typical for these receivers on 20 and 10 meters?

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 12:07 am 
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The DD-101 has a resolution of 100Hz (which is configurable). However, it's accuracy is not stated in the manual. Nevertheless, I now feel the SP-600 is performing satisfactorily for 1951 technology. Here is what happened:

1. I replaced the 0A2 and the drifting was very slightly less. I chalk this up to negligible performance variations from tube to tube.
2. I removed the DD-101 digital display shield from the oscillator tube. Bam! Every time the DD-101 shield wire moved, the frequency on the digital display changed. So, I removed the shield and replaced the original oscillator tube shield without the DD-101 connected. Double Bam! The frequency did not drift anything like before. Could it be that the DD-101 circuit loaded the oscillator, thus making it unstable?
3. I powered up my Rohde-Schwarz signal generator and put out a CW signal that I tuned in on my Kenwood TS-530S of known accuracy. I noted the Kenwood digital frequency display and compared it to the SP-600 analog dial. In the 40M band, both matched exactly. On the 20M band, the Kenwood digital display was more accurate. (The SP-600 dial read 151kHz higher.) The main thing is that the SP-600 did not drift significantly in over 40 minutes of play. For example, in the 20M band, after 41 minutes, the SP-600 CW tone was only higher than the Kenwood's tone.

I think the above falls within acceptable performance. Do you agree?


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 2:57 am 
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It would seem that way. Glad to hear you found the problem though.

With 150KC difference between the generator and receiver, it sounds like the SP-600's HF oscillator needs some touch up.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 12:20 pm 
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I'm using an SP-600 JX-21 that was "restored" several years ago by another ham. Functionally it's in pretty good condition but has some quirks when used with my HC-10. It does drift a bit, but only in one direction.

I'm using the DD-103 digital dial that works quite well. Same installation by installing the companion tube shield over V4 (the VFO oscillator). Last night I noticed several sections of the SP-600's bands would go absolutely dead and the DD-103 showed incorrect frequencies. I removed the shield and wiggled the 6C4. Things came back to life. I replaced the DD-103 tube shield but only installed it part of the way up on the 6C4. All works well now. I suspect the shield and the cable from the shield to the DD-103 were pulling the 6C4 to one side causing poor pin contact.

Harry


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 12:23 pm 
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BTW, this got me thinking which isn't necessarily a good thing. The 6C4 is very finicky as an oscillator tube. I bought about 6 of them to find one or two that work in my various receivers regardless how they score in a tube tester. Is there a direct replacement for the 6C4 in this application without rewiring the tube socket or adding components?

Harry


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 2:07 pm 
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Mikeinkcmo wrote:
Hi Les,

What kind of drift "numbers" would be Typical for these receivers on 20 and 10 meters?


Good morning Mike,

I never measured the drift with any instruments. The negligible drift on most of the 20 plus SP-600's I've owned was solved with changing the power supply transformer tap to the 130 volt connection and trying different OA2 tubes. I could listen to 20 meter ssb after a 15 minute start up with only an occasional adjustment of the tuning. Hammarlund was aware of this and corrected it in the JX-28 and VLF receivers by using two voltage regulator tubes, an OA2 and a OB2 which was for screen voltages. Also they added rectangular side panels to add rigidity to correct some mechanical stability.

John R. Leary used dual voltage regulators on the majority of his "RE-Engineered" SP-600's as well as adding angle iron strapping to add mechanical rigidity. All the Leary SP-600's I've owned were as stable as any R-390 series. One I recall that I purchased from Jon Williams many years ago was at Chuck Rippel's for an alignment that Chuck had not gotten to yet. After Jon and I made the deal, Chuck agreed to align it and repair a couple of minor problems. After the alignment, chuck set the dial to WWV at 10 MHz and let it run all night, in the morning Chuck was astounded, it had drifted upward 20 Hz! That particular Leary was No. 31 and featured in the SP-600 repair video that Chuck made many years ago.

A couple of years ago, I bought a VFO-1000 from Electronic Specialty Products: http://www.electronicspecialtyproducts. ... ersal.html
That eliminates the 6C4 and the receiver's VFO. After installation, you tune the vfo to the desired frequency then adjust the tuning dial to the best S - Meter reading using the receiver as a pre-selector. Using that, there is zero drift.

I no longer own any SP-600's after clearing out the shack of big stuff. The only boat anchor left is a fully restored National NC-183D. I'm sticking with an Icom IC-746 and a 756 Pro 3. Four wooden radios which are furniture and the wife likes. I'm too damn old to be moving boat anchors around anymore.

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Dx'ing Since '57


Last edited by Les Locklear on Sep Sun 30, 2018 3:13 pm, edited 1 time in total.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 2:58 pm 
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Harry wrote:
BTW, this got me thinking which isn't necessarily a good thing. The 6C4 is very finicky as an oscillator tube. I bought about 6 of them to find one or two that work in my various receivers regardless how they score in a tube tester. Is there a direct replacement for the 6C4 in this application without rewiring the tube socket or adding components?

Harry


The 6C4W, 6C4WA, and 6100 are all considered high reliability versions of the regular 6C4 tube. I think they may work a little better but with Hammarlund receivers that use this as the HFO (also includes many of the HQ family of receivers) you still need to hand select one for best performance. A tiny shift in element spacing is sufficient to cause drift (or microphonics if the shift occurs under mechanical excitation) yet neither of these conditions will show up on a tube tester.

A tube tester is one of the most over-used pieces of test gear available because the results of testing are often misleading. The tube is tested under specific conditions at either DC or very low frequency AC neither of which tell you how it will actually perform at RF. In a tube tester the tube is never going to reach actual operating temperature and many faults won't appear until this temperature is reached. And many tubes which test "weak" in either an emissions or mutual conductance type tester will work perfectly well in the actual circuit. With a tube tester you are likely to condemn many tubes that are just fine while accepting others that aren't operational in your specific circuit. They are good at finding open filaments, shorts that exist even at cold operating temperature, and conditions of excess gas but the tester will not uncover many faults.

Rodger WQ9E


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 3:16 pm 
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I thank all of you for very useful information. I want to emphasize that I agree that I need to align the oscillator to make all bands right on the mark. For now, I can certainly use the SP-600 for QSOs because I know that the dial readout is 1 tick mark off on the bands 14MHz and above. However, I marked this down and placed the alignment work ticket in the SP-600 for a winter project. All my equipment is in top condition, but I learned that equipment between 60-70 years old will have quirks as time goes on. Addressing those quirks is the interesting part.


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 4:51 pm 
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1. I used WD-40 on contacts and tube sockets when it was rebuilt about 5 years ago.

Mikeinkcmo wrote:
I don't use much contact cleaner, but when I do, it's the Deoxit concentrate, whatever its called. Any liquid left on a mechanical connection is going to be what I consider a dust magnet. For what it's worth, I know some use WD-40 as a contact cleaner, and I've never researched the subject to come to any conclusion, but my first inclination would be not to use it.


I would NOT use WD-40 as anything except as a solvent to clean grease off of something like the gears on an R-390/390A/391/389 series receiver, and I would make sure any residual WD-40 is washed off.
I have seen what WD-40 looks like after it has been allowed to sit for a few years (used as a lubricant to slip Absolyte AGM batteries into their steel holders), and it isn't pretty! It deteriorated, and turned brown and somewhat sticky. Not good. It's nothing I want on a tube socket, or anything else.
I agree with Mike, and that it will be a big time dust magnet!
That being said, I would caution on the use of anything that stays on a socket, or is allowed to soak into a switch: I have used DeOxit D5 on the squelch tube socket on a Gonset Communicator III, and was not able to set the squelch again (rushing noise always present).
I left the DeOxit D5 on there for a week, no improvement. I then spray cleaned the tube socket with a non-residual cleaner, and Voila! the squelch tube started working again. Fortunately, the material didn't soak into the ceramic, or I would have been replacing the socket.
I have run long term (several months) scientific tests on phenolic switches, and the application of DeOxit D5 showed a marked and definite increase in leakage resistance between switch contacts, so know that it is not a cure all, and care must be exercised in its use.
The changes I saw were in the 100,000's of MegOhm range, but they were there. And, if you have a very high impedance circuit such as I had with the Gonset (also think classic Geiger counters as well: High voltage, low current equals very high impedance [R= Big E, divided by very very tiny I]) that kind of leakage will sink you!
If the 6C4 is as finicky as we are led to believe, and extra complications such as unanticipated leakage or change in RF characteristics added by a contact treatment material (DeOxit D5 or WD-40) are added to the equation, then it makes it less likely the oscillator will work well or at all.
BTW: I will add it to my list of things to do to run a long term test on WD-40 and its effects on phenolic switches. I didn't do this in the first place, as it's not something I would ever consider beneficial to use for cleaning sockets or switches.
Another take away of my investigations is that you can use mild to aggressive (Freons/CFC's, alcohols, 409, Simple Green, 409 or Simple Green with 30% Ammonia [Nicotine removal], and Tarn-X [in relative order of increasing cleaning action]) as long as you work them into the switch or socket, provided that you quickly rinse them off (I used water) so that they are not allowed to soak into the switches or sockets.
Dry times to normal function are surprisingly fast (applied 500 volts test voltage within an hour typically), and can be accelerated with the use of a hair dryer (heat gun NOT advised!).
Just my two cents worth...

-Tom


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 7:48 pm 
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The problem with your squelch was most certainly not that the DeOxit was conductive. Rather, by spraying it you dissolved some conductive crud which bridged the tube sockets.

It's never a great idea to spray anything into a radio except perhaps freeze mist. Even that can instantly create water condensation and mess up high impedance circuits.


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Sep Sun 30, 2018 8:06 pm 
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w3jn wrote:
The problem with your squelch was most certainly not that the DeOxit was conductive. Rather, by spraying it you dissolved some conductive crud which bridged the tube sockets.

It's never a great idea to spray anything into a radio except perhaps freeze mist. Even that can instantly create water condensation and mess up high impedance circuits.


Interesting take on the issue... I have cleaned the unit before, so I tend to think it was the DeOxit... I will pull the Gonset, verify socket cleanliness, and if possible, measure loss to ground before application of the liquid D5 (it was not sprayed, but I dipped the first 1/8" of the tube pins into a tub of D5), then measure loss after treatment and slopping it between the tube socket pins.

Not worried about spraying a non-residual cleaner into a radio or piece of equipment: The condensation is gone soon enough.

-Tom


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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Oct Tue 02, 2018 1:07 pm 
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Quote:
I used WD-40 on contacts and tube sockets


I was surprised it took a few posts for someone to call this out. WD 40, both a solvent and and oil...you don't want oil on those contacts and tube socket pins..not to mention possible splatter on other components - even if you applied with the tiny red straw. Though parts of the radio are sealed, any dust could collect on those oiled parts and cause problems.
DeOxit is a good choice, though it is relatively expensive.
Normally you just want to remove oxidation on nickel or silver plated contacts; now in your case you have to "degrease."

You can get a spray can of electrical contact cleaner at Home Depot in the electrical section for cheaper, I suggest the can that says "Plastic Safe." You'll notice that it evaporates quickly.

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Oct Sat 20, 2018 8:23 pm 
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I did not see in the above the fact that the intended commercial use of these receivers was in applications where they were never turned off except for yearly scheduled maintenance. In military use there was an operator present. Also, the BFO can drift. Thermal cycling after storage is always hard on electronics.
73,
Pat

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 Post subject: Re: HAMMARLUND SP-600 JX-1 - Drifting
PostPosted: Oct Sun 21, 2018 3:34 pm 
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Location: Bethany Ontario
Stabilizing/regulating of the bias supply, filament voltages and B+ voltages make a huge difference in my SP-600.

I used the KD0HG mods from ER magazine, and the drift after a 5 min warmup is negligible.

There's also Perry's article on the subject too. Very informative stuff to consider with the SP-600.

Al


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