[Hammarlund] Ronald McDonald's SP-600

[Richard Knoppow]

     There is a handbook for the Northern Radio version of the SP-600 at:
<https://www.rigpix.com/hammarlund/sp600j_northern159_manual.pdf>
The schematic is in the same file and at:
<https://www.navy-radio.com/manuals/northern_sp600_schem.pdf>
  It is essentially identical to the Hammarlund SP-600-JX 17.
      There is also a modification work order showing how to install the 
gain trimmer and a dropping resistor for the dial lamps. The dropping 
resistor became a stock item on the JX-17. I've installed a couple of 
them, they do extend the life of the dial lamps considerably, the SP-600 
is a lamp eater. I think this is at BAMA.
    Changing to LED's helps a lot more and gives more uniform 
illumination to the dials.
     I will repeat that I think there are a lot of SP-600's out there 
which work but are really broken and do not perform up to their 
capabilities. They are really quite remarkable receivers.
     FWIW, you can improve the sound on broadcast stations by running it 
in Manual RF gain. The AVC is too fast resulting in a lot of low 
frequency intermodulation. Just try it and see how much cleaner it 
becomes in manual.



On 3/7/2026 6:42 PM, Jacques Fortin wrote:
> Well... I'm sorry but...
> Northern RADIO (New York) have nothing to do with Northern ELECTRIC (Toronto
> + Montreal).
> Northern Electric was the manufacturing arm of Bell Canada (counterpart of
> Western Electric).
>  From the ID tag of the modified SP-600s, they were modified by Northern
> RADIO in New York.
> 
> 73, Jacques, VE2JFE in Montreal
> 
> -----Message d'origine-----
> De : D LAST_NAME_SHORT: T <k0dan at comcast.net>
> Envoyé : 7 mars 2026 10:05
> À : Jacques Fortin <jacques.f at videotron.ca>; dickburk
> <dickburk at ix.netcom.com>; ranickels at gmail.com; hammarlund at mailman.qth.net
> Objet : Re: [Hammarlund] Ronald McDonald's SP-600
> 
> I believe Northern Electric modified stock SP600's under govt contract (Cold
> War) for the Navy? The mod was specifically for diversity RTTY reception.
> 
> I've had the model in the photo for a decade or more...it is a gem and
> pleasure to use. Of course I'm using it as a straightforward general purpose
> receiver (500 kHz thru 56 mHz). No product detector but it copies sideband
> fine using RF gain and volume controls.
> 
> I am thinning out my boatanchor collection, and this receiver is available
> for those who wish to add it to theirs.
> 
> 73,
> Dan
> K0DAN
> Kansas City
> 
>> On 03/06/2026 9:41 PM CST Jacques Fortin <jacques.f at videotron.ca> wrote:
>>
>>   
>> Northern Electric ?
>> OMG, why ?
>> I worked for the company when it became Nortel.
>> You do not want to know what happened with...
>>
>> 73, Jacques, VE2JFE in Montreal
>>
>> Perhaps Northern Electric. The built SP600 fro diversity use. The JX-17
> version of the SP-600 was very similar. AFAIK these were painted in standard
> SP-600 colors.  It's possible fairly large lots of receivers might have been
> finished in custom colors for some customers.Sent from my GalaxyRichard
> KnoppowLos angelesWB6KBL
>>
>> ______________________________________________________________

-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998