[Hammarlund] Age list of HQ-129-X?
Richard Knoppow
1oldlens1 at ix.netcom.com
Mon Mar 23 13:03:13 EDT 2020
I have to cudgel my memory. I think it was published about
1948 and want to attribute it to Paul Lee but am not sure.
The mod used cathode coupled 6SL7s I think. A type of circuit
developed by Keats A. Pullen.
I don't think you need to article, just restore the circuit
to the one in the schematic. Hopefully, the original sockets are
there.
When I used mine for an experimental test bed I used socket
adaptors so it was easy to restore it to original.
If the set has its original caps in it they should be
replaced. The best replacements are polypropylene, not very
expensive but there are a lot of them. Same for the SP-600 if it
has the original paper caps. Not all were made with Black Beauty
caps but it doesn't matter, any of the old paper caps should go.
Some SP-600s were modified with disc ceramic caps and some were
built new that way. Those for the most part will be OK but check
for splits etc where the leads enter the case. Mica caps are
mostly OK. Polypropylene are superior to low-K ceramic for most
uses and definitely superior to Hi-K ones.
There are some caps inside the tuning case in the 200/400
series, can be a PITA to get to.
The Super Pro was the most expensive and probably the best
receiver on the market during its life. The RCA AR-88 may be
better in some ways and was probably twice the cost but were
never sold on the civilian market.
Once in a while you will find a military Super Pro with two
holes above the main dial. Mine had that. Those were for a fixed
frequency oscillator, similar to the one in the X version of the
SP-600 and for the same purpose, stability for diversity system.
The receivers were used in pairs with a diversity combiner of
some sort.
Also BTW the Super Pro was thoroughly superior to the SX-28
Somewhere I have a military handbook which shows spurious
responses of several receivers of the time. The Super Pro has
only on spur, the image response, while the chart for the SX-28
looks like a corn field. I have never been able to find this book
on line.
On 3/23/2020 9:35 AM, Don Cunningham wrote:
> Richard,
>
> Thanks for all that information. First, my SP-400 has had the
> mod you referenced, and I would really just as soon put it back
> to normal here as well. If you or anyone can remember which
> issue of CQ that the article was in, I'd like to find a copy of
> that article to help in the re-wiring. The seller of this one
> said it made the receiver "much quieter", and since it was DOA
> it was certainly quiet!! I found 5 tubes that wouldn't come up
> at all, and figured the poor packing job he did contributed to
> the demise of the tubes, so I just replaced them. Still very
> silent (dead), but will get it back in the queue soon and trace
> why. Most of my old receiver use is 40M or below, so quietness
> is a relative term anyway. I'll keep all these improvements in
> mind, and I thank you for them. I also have a BC-779, in the
> original rack, but it looks truly all original and was stored
> for a LONG time in poor storage. It will be a real project
> that may be left to the next guy.
>
> My SP-600 was one of the later ones with all disc caps instead
> of brown beauties, and I did get it running in a fashion, but
> lots of necessary cleaning and reviving to do on it. The
> Hayseed cap was the first thing to go in this one before the
> variac even. I made a purchase a few years back that I haven't
> regretted. Harbor Freight had their 1000 lb "lift table" on
> sale and I invested in one, otherwise I would no longer be
> doing these "anchors". You do have to get it up the initial 5
> or 6 inches, but you can build a ramp or try to always store
> new arrivals on a shelf so you can just pump the table up to
> the proper level. Mine goes to 42" which seems to fit around
> here all places. It is NOT cheap nor cheaply built, like much
> of their stuff once was and has kept me able to play longer.
> Thanks again,
> Don, WB5HAK
>
> On 3/23/2020 11:06 AM, Richard Knoppow wrote:
>> The SP-400 is a very fine receiver. My first station receiver
>> was a surplus BC-779, a version of the SP-200. The 40Mhz
>> version used a different arrangement for the RF stages with
>> parallel fed plates, series fed in the standard and MF models.
>> I am not sure what is in the 400. I think the 400 may not have
>> the Faraday screens in the antenna coils.
>> One thing all of the series need is a regulator for the LO.
>> A VR-150 under the chassis works fine but the plate resistor
>> for the LO should be changed from 12K to about 8K. Without the
>> regulator the LO tends to pull with the AVC voltage. The late
>> 400 also had a TC cap in the LO across the tuning capacitor. I
>> don't know the value, maybe about 5pF, N-750. Will reduce the
>> warm up drift. I let mine run all the time and it was very
>> stable that way. Since mine had been modified when I got it I
>> tried all sorts of things in the RF, converter, and LO. The
>> original circuit works about as well as anything. Mine had the
>> cathode coupled triode mod shown in an old CQ magazine. It
>> worked but the original circuit works better. The modified
>> circuit may have been quieter but it loaded the RF coils so
>> reduced RF selectivity.
>> Anyway, its worth putting some work into. I still have this
>> receiver.
>> I have two SP-600-JX receivers on the back burner. My
>> problem is that I can't lift them any more. Hayseed Hamfest
>> makes a correct power supply cap for them. If yours have the
>> original paper caps they need a complete recaping. You may
>> find a few mica caps bad too. Check the 51pF cap in the BFO
>> since it seems to develop a jump.
>> Do NOT bend the tuning capacitor plates. They should be
>> straight. However, the stators and fixed with screw clamps and
>> fiber washers and can drift off. They are not difficult to
>> re-center. Some people seem to have done plate bending to get
>> calibration. Of course they make it impossible and its usually
>> impossible to straighten out the plates again. I think they
>> were trying to compensate for mis centered stators.
>>
>> On 3/20/2020 9:04 PM, Don Cunningham wrote:
>>> I also have two of the HQ-129X in the repair queue. Both
>>> have the white lettering, but are not stored where I can see
>>> the serial numbers. I am currently working on reviving a
>>> Super Pro SP-400-X and an SP-600, so the 129's and an HQ-180
>>> will have to wait.
>>>
>>> Hayseed filter caps have always worked fine for me, and are
>>> the first things I do before even firing the rig up
>>> initially. I am more of a "user" than doing restorations, I
>>> just like the old receivers.
>>> 73,
>>> Don, WB5HAK (formerly WPE5CTN MANY years ago, HI)
>>>
>>> On 3/20/2020 4:17 PM, Ray LaRue wrote:
>>>> I have acquired a rather nice HQ-129-X in good physical
>>>> condition. I have not yet recapped it but will get to it
>>>> shortly. I am pairing it up with a nice rebuilt Johnson
>>>> Ranger for an operating "classic" station, to go along with
>>>> my rice boxes.
>>>>
>>>> Is there a list of serial numbers online where I could
>>>> estimate it's age? The serial number on this one is
>>>> #14574, stamped into the back of the chassis.
>>>>
>>>> Your attention is appreciated.
>>>> Ray, W4BYG
>>>>
>>>
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>
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Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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