[Hammarlund] SP-600JX14 problem - main tuning capacitor sync

Richard Knoppow dickburk at ix.netcom.com
Sat Nov 16 16:45:24 EST 2024 

   A note: I always forget something. If you re-cap the receiver use 
polypropylene plastic dielectric caps rather than ceramics. NP0 ceramics 
are OK but the discs may be "hi-K" and plastic will be better. They were 
not available when the military and Hammarlund re-capped older receivers 
that had paper caps.
    My only comment on electrolyics is that I don't like restuffing caps 
and prefer to use terminal strips. Not authentic but no one is going to 
look under the receiver. For the most part mica caps do not need 
replacement.
     The SP-600 is an extremely good receiver. There are many out there 
that work but are broken because people don't know how to fix them. Get 
a bad rap for faults that are not inherent in the receiver.
     Lots of service info available via the web.

On 11/16/2024 12:31 PM, Bill Cotter wrote:
> Richard,
> 
> You have interpreted my problem correctly, I believe. The previous owner 
> did not move any of the gear train, but merely refaced the dials. 
> However, the person he bought it from was known as a "Golden 
> Screwdriver" and may have had a hand in it. There is also a couple of 
> screws and a threaded plate missing that secure the case and variable 
> capacitor, suggesting someone may have had the capacitor out. The drive 
> link and spring for the capacitor you referenced are installed correctly.
> 
> So what I feel must be done is to figure out how to move the drive gear 
> on the capacitor a few degrees to allow it to fully mesh, and not effect 
> the synchronization of the dial drives and stops. I'll let everyone know 
> how it goes.
> 
> Thanks es 73 Bill N4LG
> 
> 
> At 01:36 PM 11/16/2024, Richard Knoppow wrote:
>>    I interpreted your problem as saying the capacitor did not fully 
>> mesh. The dial position is adjustable as stated but that won't change 
>> the stop points for the cap. It should fully mesh regardless of the 
>> dial alignment. Its been too long since I was in the tuning drive and 
>> I don't remember how the stops are arranged but, if the former owner 
>> worked on the gearbox he might have gotten the gears misaligned.     
>> The cap is driven by a crank with a spring coupling. The spring is to 
>> take up any overtravel. Make sure the drive crank is fastened to the 
>> lever on the capacitor correctly. If you have to get into it be very 
>> careful the spring doesn't go flying off to be lost.      If you get 
>> it running right I an give you some detail on getting the dial and 
>> moving pointer aligned mechanically. On 11/16/2024 9:34 AM, Bill 
>> Cotter wrote: > Thanks, Al. I will remove the front panel and check 
>> the relationship > between the dials, stop pin and three-screw slots. 
>> > > 73 Bill N4LG > > > At 10:34 AM 11/16/2024, AW wrote: >> Hi Bill, 
>> >>         It sounds like the previous owner didn't get the new 
>> paper >> dials on properly, or didn't move the dial to correct the 
>> error.  The >> dial has 3 slotted holes at it's center, and is held 
>> on place by 3 >> screws thru a disc.  They can't be accessed unless 
>> the panel is off, >> or at least possibly loosened and moved back.  
>> (I hope that makes >> sense.) There might be enough adjustment 
>> available to get it right. >>         At the lower end of the 
>> band, the dial should indicate zero on >> the logging scale, with the 
>> freq. dial right on the left end of it's >> scale. And the stop pin on 
>> the stop. >>         Shouldn't have to (don't) mess with any 
>> gearing. >>         Take a look at Andy Moorer's 
>> instructions.  As he says, re: >> the manual, "The instructions are 
>> often more confusing than helpful. >> Â <https://www.hammarlund.info/ 
>> GearTrainAlignment.html>  >> 73, >> Al, W8UT >> >> >> >> On 11/16/2024 
>> 9:59 AM, Bill Cotter wrote: >>> Hello everyone, >>> I have a nice 
>> SP600JX14 I am restoring to work with my globe King >>> 500A 
>> transmitter. I have the RF deck and side porch recapped with >>> 0.01 
>> 600VDC disc ceramics and all out of tolerance resistors >>> replaced. 
>> After reassembling the RF deck on the chassis, I noticed >>> something 
>> strange. >>> When the main tuning dial is set to the bottom of the 
>> band and the >>> logging scale is set to zero, the main tuning 
>> variable capacitor is >>> not fully meshed. It is all but about 10-15 
>> degrees meshed. The stop >>> pin is resting against its stop, as 
>> expected. When I rotate the main >>> tuning to the highest frequency, 
>> the dials do not reach the expected >>> end point and the stop pin 
>> does not reach its stop. I assume the main >>> tuning variable 
>> capacitor has reached its end point. >>> It appears that the main 
>> tuning variable capacitor is out of sync >>> with the dial indicators. 
>> The previous owner refinished the front >>> panel and applied new dial 
>> scales to the dial plates, but he never >>> disturbed the gearing 
>> behind the dials. >>> Any thoughts on how to correct the not-fully- 
>> meshed main tuning >>> capacitor problem? I have all the digital 
>> copies of manuals with gear >>> set exploding diagrams and tear down/ 
>> reassembly directions, but I >>> haven't come across the 
>> synchronization procedure. >>> Thanks in advance. >>> 73 Bill N4LG >>> 
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>> http://www.qsl.net/donate.html -- Richard Knoppow Los Angeles WB6KBL 
>> SKCC 19998 
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> 

-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

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