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 Post subject: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Fri 20, 2017 3:13 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
A fellow forum member suggested I make a thread about my restoration. I'm always hesitant to be honest since it requires a lot of effort to post a whole restoration, and also partially because I tend to get distracted by something else after 50% of a restoration. :oops: But at the same time, I'd like to hear everyone's input, so here it is.

I bought this receiver on eBay and I paid a lot of money for it, not gonna beat around the bush, I paid $800 CAD including shipping. (Shipping is a technicality as far as I'm concerned! :P ) Here are a few pics.

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I love those funky tube shields! I had never seen anything like them before. They remind me a bit of the IERC tube shields though. They are actually one of the reasons I was drawn to this particular receiver. It also looked to be in reasonable shape. And it had some mods that just looked interesting.

It is a JX-7 serial #3664 formerly owned by the United States Department of Agriculture Forrest Service and is now a resident of the great white north.

The first mod is in place of the crystal frequency control. It's a group of four frequency converters made by Vanguard Electronics Labs with frequencies of 47.666, 49.000, 52.333, and 53.667 MHz. They are solid state units that obtained their power from the B+ supply fed through a dropping resistor.

The other device is a...well its a...uh...okay, you caught me, I don't know what it is. I haven't looked too closely at it yet. All I know is that it was wired to the B+ and A+ via the modded phono terminal strip on the rear of the receiver. It was also fed to the diode terminals on the rear as well as the AVC terminals. I know that the diode terminals have also been rewired internally.

There is also a third tube in the IF section of the chassis. Product detector? All I know is it's not supposed to be there and it won't be in the end.

I haven't done much digging under the chassis but I did try a slow power up on my variac. I got some AC hum, the tubes lit up as did the dial lights, none of the controls made any difference. Then a capacitor burned up somewhere with a fizz and a crackle followed by that wonderful burnt black beauty smell and white smoke. It's somewhere in the RF section.

Since then, I've stripped the receiver down mostly. Here are more recent pics.

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The dials are not yellow really. More a pleasant cream color. I prefer that over bleach white dials. They're too white and don't have the proper patina. Even if they were more yellowed, I'd likely leave them that way. Besides, the slightly raised dials look so much better than a modern overlay!

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With all the mods and recapping to do, I figured I would tear things apart and start from the ground up more or less. Maybe that was stupid of me? Oh well. I figured it would allow me to clean things more easily right off the bat. I'm cleaning the band change and tuning mechanisms right now. They were gummed up with grease and the tuning mechanism was sticking and slipping rather than running smoothly.

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I've thought about cleaning the parts with Brasso. But then again, I like the patina. Would that be too abrasive to the friction drive components? I don't want to screw up this famous tuning drive, that is, if I haven't already. My hair will be a few shades grayer by the time all that is put back together, I'm sure. If not fallen out completely.

I'll end this post off with a picture of the famous SP-600 immortalized in a video game next to the also famous Sean Connery as James Bond of course!

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It's an old game, the graphics are terrible.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Fri 20, 2017 7:13 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3381
Location: Monterey California USA
I think the Vanguards were set to US Forest Service FM relay frequencies of the 1950's. If so then that other mystery chassis is probably an FM adapter, which also explains the squelch control. If you were reading the frequencies of the crystals in the converters then you would need to subtract the IF intended, from them, to determine what frequency they are for. The converters might have a 455 kHz output or an output that matches the upper IF of the SP600. In other words, I don't think the converters are fed to the antenna input of the receiver but rather the fixed IF stage.

They sure spent a lot of time on those mods!

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Fri 20, 2017 5:08 pm 
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Joined: Jul Tue 21, 2009 1:38 pm
Posts: 690
Location: SW WA state
Nice catch!

I have yet to fully restore an SP-600, it's on my list of things to do (my JX-17 has been in everyday service since 1986).
I think George is right on the converter: USFS did use VHF AM in the 30-32 M/c region, so if they used it, there would have been no reason to modify the receiver, as it would have received it fine as-is.
Now, if they used a slightly higher frequency, that would have put them in the FM two way portions of VHF low band. They still would be able to receive direct, but would need some way to properly demodulate FM.
So, the converter could have possibly been used for channelization, and the other mod you saw could be for FM.
Another thought, is that the receiver could down convert from VHF FM High band (150-174 M/c), and popped it out somewhere in the tuning range of the SP-600...
Best of Luck!


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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 1:25 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
Yes, Geoff, I meant to mention that those are the crystal frequencies. I'm not sure what the IF is for the converters.

Process of elimination when putting the tubes back in shows that the extra tube mounted on the chassis was a 6C4. The three tubes in the mystery device are a 6AL5 and two 6BH6 tubes.

I think you're right, Tom. The converters have two RCA jacks. One for the antenna input and one that ran to the receiver antenna socket. The rotary switch appears to have switched them in and out of the antenna circuit while simultaneously controlling power to them.

Here's a pic inside one. They each have four transistors.

Image

They're nifty little things, but I don't think I'll ever do anything with them. Maybe I should try powering one up?

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 1:48 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3381
Location: Monterey California USA
By the time those solid state converters were made, the USFS had been on FM for a long time. Hence I still think the extra assembly is an FM adapter, the 6AL5 probably being a discriminator. USFS ceased using AM on VHF after the end of WW2 and made their own FM gear briefly before buying factory made equipment by Motorola, Radio Specialty and others. Interestingly, the last VHF AM mobile equipment they used, had a tunable receiver.

I take it from the photos that the channel switch at the upper right switches the outputs of the converters to the antenna input and probably applies power to the selected one. I seem to recall those converters being sold by Vanguard in the 1963-1965 era.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 3:15 am 
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Location: USA
Great photos and it's in nice shape compared to other SP-600 receivers I have seen.

Interesting that your receiver was used by the Forest Service. Looking forward to following your thread and learning from it.


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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 4:21 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
I've never been much interested in anything above 30MHz, so I'm sure you all have a better idea than I do. That's right, Geoff, the switch was wired exactly like that.

Thanks Brad! I'm never very happy with my photos. I'm quite well versed in photography. Digital and film, and I find that stuff on film always looks better than digital. I always get at least one gem per roll of film! :P

I hope I don't disappoint with the restoration. It's gonna be a long one. I don't get a lot of time lately. With all the equipment at work breaking, I'm going into overtime just keeping everything running. I came home two hours late today, but I still had some time to clean up the steel panel with my dremel tool. It's not perfect, the color is uneven and such, but it looks snazzy with the brass gears on it! I'll post some pics tomorrow.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 3:21 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Morris Plains, N.J. 07950
Here's a link to Andy Moorer's site, which contains numerous SP-600 manuals. Note particularly that that last manual on the list is an illustrated parts break-down of every nut, bolt and gear. That might be helpful in reassembling the tuning mechanism.

http://www.jamminpower.com/main/sp600.html


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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sat 21, 2017 3:56 pm 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
Joe Connor wrote:
Here's a link to Andy Moorer's site, which contains numerous SP-600 manuals. Note particularly that that last manual on the list is an illustrated parts break-down of every nut, bolt and gear. That might be helpful in reassembling the tuning mechanism.

http://www.jamminpower.com/main/sp600.html


Yes, I'm quite familiar with his manuals! I've already ordered a print out of five of them that apply to this receiver! I have the PDFs downloaded, but I prefer to read from paper than my computer screen. It's easier on the eyes and allows me to look at multiple pages at the same time without having to flip back and forth.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 3:26 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
I'm finished the tuning mechanism and it's working like a champ! Ten times smoother than it was now that all the dirt is gone from the friction components. I still have to finish reassembling the band change mechanism and aligning it to ensure that the contacts on the turret will line up correctly with those on the RF section. I'm not exactly sure how I'm going to do that. Maybe compare the turret position to that of another receiver. I'll figure out something I'm sure.

Here's a pic of the steel back plate after cleaning. As I said, I cleaned it with my dremel tool and some brass wire brushes. Then I wiped it down with methyl hydrate to clean the surface. It's not very evenly colored, but at least all that dusty oxidation is gone.

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Here's a pic of the tuning mechanism reassembled. I cleaned the brass parts in kerosene to take the grease off. The spacers and other metal parts were cleaned with Brasso then methyl hydrate. The dials were cleaned with a damp cloth. They still have a few spots, but I don't want to risk using a solvent or anything on them. I already know from testing near the center hole that methyl hydrate will remove the paint.

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So far, things have been going quite smoothly. Literally! :P That tuning mechanism is so smooth! I sat there for five minutes just spinning it back and forth! I can just imagine how great it will be when I'm actually receiving something! I hope I can do as well with the rest of this restoration!

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 4:43 am 
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Looking good, better turn off the flashlight though.

Mike

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 5:30 am 
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What do you do to keep the bare metal from oxidizing again in the future? I always wonder about this. I know products like Bar Keepers Friend have waxes that protect bare metal. Metal polishes also have protective agents. Some people spray paint or clear coat on the metal. Brass and aluminum have natural resistance to oxidizing, but bare steel is my main concern.

Norm

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 6:26 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
Good eye, Mike! I noticed the flashlight shortly after posting! At least it's a rechargeable so I don't have to go out and buy batteries.

Yeah, I thought that myself, Norm. I considered clear coating the steel but didn't bother. If I were to do that, I would like to have removed it completely and cleaned it up better and all beforehand. I figure it will just oxidize again over time. Assuming these radios came from the factory without anything on the steel, and seeing how the steel pieces looked after 65 years, several of which were likely not in ideal storage conditions, I figure it shouldn't be too bad.

Does anyone know if the steel parts were cadmium coated perhaps? They weren't green, but they didn't really have any rust either. Just a sort of dusty oxidation with some discoloration here and there.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 3:46 pm 
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Location: USA
Thanks for the photos with the panel removed. The dials and band indicator appear to be in great shape. I have seen some SP-600 dials with delaminated markings. What did you use for lubrication, and did you lubricate just the bushings?

I don't want to divert the thread but if anyone has ideas on how to remove what I believe are tar spatters from the front panel for my unit, I'm looking for ideas actually found to work, and just send me a PM. I have tried without success dilluted dish soap, dilluted and non-dilluted 409, and Goop hand cleaner - all applied with a soft-bristle toothbrush.

Brad


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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 4:49 pm 
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Location: Seattle WA US
For tar, I've had good luck with Naptha, aka Ronson Lighter Fuel.
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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 7:17 pm 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
bfo wrote:
Thanks for the photos with the panel removed. The dials and band indicator appear to be in great shape. I have seen some SP-600 dials with delaminated markings. What did you use for lubrication, and did you lubricate just the bushings?


I have another SP-600 where the paint is flaking off the dials. With the sort of raised black portions, I feel that after removing the paint, a very thin enamel could be flowed onto the dial and worked around with a fine brush to sit in all the low portions. Sort of the way they make a lot of pins.

I used 3 in 1 on the bushings and white grease on the ball bearings. I'll also use the white grease on the sliding components of the band change mechanism.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Sun 22, 2017 7:41 pm 
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Keep in mind brass gears need no lubrication. Use lubricants sparingly as they simply collect dust and eventually dry out.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Mon 23, 2017 1:33 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Morris Plains, N.J. 07950
Amen to what Mike said. Remember that any excess lubrication in an SP-600 will invariably find its way to the brass rollers and cause the tuning to slip.


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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Wed 25, 2017 2:29 am 
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Joined: Dec Mon 31, 2012 11:09 pm
Posts: 189
Location: Portage le Prairie, Manitoba
Yeah, I didn't lube the gear teeth at all. Just a tiny bit where they rotate on the shafts.

I spent the last few days "fixing" the rear of the chassis. The previous owner had cut a large hole to accommodate a three hole grounded electrical socket. I wanted to install a modern EMI filter socket for convenience. Here's what it looked like before I did anything other than remove the old socket and make some marks for my cuts.

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I cut out a rectangle with my new piercing saw. Such a useful little device! Laborious to use and a little difficult to keep running straight compared to the much wider blade of a hack saw, but much less dusty than using my dremel tool and a cutting wheel.

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I then manufactured a little plate to hold the AC socket and cover up the unwanted holes. I used some 1/16 inch aluminium sheet that I had lying around for the plate and used a hack saw, piercing saw, drill press, power drill, and some hand files for the machining. It's funny, I have a milling machine that could've done all of that! But I've never gotten around to buying any end mills for it. Here's the plate:

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And installed with the fuse holders and AC socket:

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And through the chassis for curiosity's sake:

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I have a few more things to do for the power supply. Cleaning up (dusting off) the chokes and transformer, as well as desoldering their terminals in preparation for rewiring. Other than that, I'm waiting on parts. Mostly wire! :P I have all sorts of random bits of wire lying around, but I want to at least half ass color code things, so I'll have to wait until the new stuff arrives.

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 Post subject: Re: Hammarlund SP-600 JX-7 Restoration
PostPosted: Oct Wed 25, 2017 3:21 am 
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Speaking of wire, new, it isn't cheap at all, but at ham fests you see boxes of it under tables, begging for a sale. I always check em out, you never know what you might find for a buck or two.

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