I have had a Hammarlund SP-600 JX-17 for at least 15 years. Now that I have my Collins R-390 working properly i am going to give the Hammarlund a good going over.

Thankfully it has ceramic disc caps instead of the tubular caps which saves a lot of work.

I read somewhere that this receiver was designed to still operate decently with marginal tubes and components. I can attest to that as maybe 12 years ago I tested the tubes and most were weak, yet the receiver still worked very decently. Finally got to the point where I was swapping tubes around to get the receiver to work right so I ordered a new set of tubes about 5 years ago. I then did an alignment.

I am thinking that all I need to do is replace some resistors and then do a proper by the book alignment. What type resistors should I use? I would normally automatically use metal film resistors, but don't know how well they will work in RF circuits. My plan is to go ahead and replace all the resistors unless of course there is a very good reason why I shouldn't.

The receiver works so good that I can pick up Cuba with just a very short piece of wire inserted in the antenna jack.

My normal antenna is 48' of wire from an AA5 antenna coil strung around the inside of my 12' X 12' building near the ceiling and connected to a ballun from a defunct outdoor antenna. The antenna works very well and is pretty much non-directional.

The SP-600 JX-17 is a great receiver and it is nice that you don't have to deal with all of the black beauty caps.

I have used standard metal film resistors from Mouser for years and they work fine at RF. I remember someone on the boatanchors mailing list using an RF analyzer on them and they have insignificant inductance for use up through 200 Mhz. (and probably higher).

Some SP-600 receivers were built with power supply filter chokes potted in contaminated tar which becomes increasingly conductive over time. Mine was one of these and I had to replace them (they lead to power supply over heating). But I think these were used only over a limited part of production and mine had the black plastic caps so your SP-600 is probably safe.

Radio Havana Cuba still has some interesting radio related programming which is rare these days on shortwave radio. Arnie Coro CO2KK does a lot of the English language broadcasting and is a very interesting person. I spent some time with him in Fall 2000 while I was in Cuba and here are some photos of Arnie with some of his radio gear. Arnie and his charming wife were very fun to meet.

Rodger WQ9E

Very cool. I sometimes listen to his program.

I'll just use metal film resistors then. Will more than likely be a complete going through of this receiver which I plan on taking my time doing to be sure it is done right the first time.

No big rush in me doing this as the R-390 works exceptionally well using the same antenna.

I looked at the SP-600 and found where I had replaced the two audio coupling caps with a couple electrolytic caps some time in the past. I went ahead and replaced them with a couple .1 uF film caps.

Listening to the internet feed of WRDV broadcast to it through my two tube broadcaster as I type. I had forgotten just how good the audio sounds through the wall mount jukebox speaker with original 10" Rola speaker installed. The Hammond 600/4-8 ohm transformer is mounted in the wood speaker box as well.



My plan is to have a similar looking box built for the 15" Jensen used with my R-390 and then mounting it and setting the R-390 to the right of the SP-600.

Like I've posted before those old jukebox speakers make the best speakers for communications receivers.

I would guess that the first two r.f. tubes would be the place to put your money and probably the local oscillator tube.

I have said this many times before: It behooves you to set the band switch in between two ranges, if you are going to open up the r.f. deck. This disengages the band-switch contacts. Probably most important when you try to put it back together again.

Good luck,

Charlie

I'll definitely remember that about the band switch. IIRC the online restoration article I found mentioned that. I already have a full set of NOS tubes except the 6V6 is new manufacture, but will probably go NOS as the new tube is loose in the socket.

My plan is to start working on replacing resistors then do a by the book alignment. I may revisit my antenna as well. I inserted a piece of wire in the antenna jack and I had to use a real short piece of wire to keep from overloading the radio with the signal from my two tube 6GY6 broadcaster. I will probably eliminate the napkin and simply connect the antenna wire directly to the center conductor of the coax cable.

Your receiver has only a single pin on its antenna connector? Maybe it has been changed to that. I thought most had a twin input using an amphenol UG-103/V connector.

Very hard (for me) to find these. I have been to three Dayton Hamventions, without finding any, new or used. I got a couple used ones from Fair Radio.

I just saw in an old RADIO and TELEVISION NEWS magazine (August, 1955) a mechanical i.f. filter for the SP-600.
You remove a certain i.f. tube, plug in this module, replace the tube in one of the sockets on top (the module adds another tube of its own).

I have never heard of anyone with a SP-600 with this addition.

Charlie

I read somewhere that the Sp-600 could come with either the double pin connector or the single pin connector depending on when it was made. All that is required to make the balanced double pin antenna connection into a single pin unbalanced antenna connection is to ground one of the two pins. My guess is the balanced antenna probably was not all that popular for the receiver's intended use.

My JX-17 has a standard PL-259 single-pin connector. Looks original.

Dave

Collins made adapters for several radios as well as some small niche enteprenuers.

Carl

I've always loved how good the audio sounds from the Hammarlund. With my current speaker I can fill my 12' X 12' building full of sound.

[quote="Burnt Fingers"][quote]
Collins made adapters for several radios as well as some small niche enteprenuers.


I found this advert only this morning in the "What's New in Radio" column of R&T News (Aug 1955, pg 78) "now available from Hammarlund Manufacturing Co". So they were at least marketing this thing. Collins could have furnished the filter. Collin's patent probably was a factor.

I just have never heard mention of it.

What did the filter do concerning the performance of the receiver?

The "ad" says; "The unit, which is available for bandwidths of .8, 1.2, 3.1, and 6 kc. at 6 db down, can be completely installed in a matter of seconds..." I assume the purchaser selects which B.W. he wants and he will have that as a fixed B.W. for his receiver, for the man, who must have or, need a mechanical filter.

If it goes in "in seconds", there probably wouldn't be any B.W. switch mods and where in the i.f. strip it is located, or, how it works with existing filters, is not mentioned.

It adds an extra tube to the count though.

Charlie

It must be better then

Yeah, right

Looking at the photograph, the two tubes sitting on top of the "can" , I hope they can still get the receiver back inside its cabinet w/o knocking off the tops of the tubes.

Charlie

National did the same for the NC-400 and it had its own part #. For the last run of HRO-60's they built their own adapter with either 800 or 1.2 filters, CW and RTTY for Tropical Radio. Collins also built an adapter for the HRO-50/60 family much earlier plus the 75A2 I believe. The early Collins filters had high insertion loss compared to the 75A4 and S Line versions.

Carl

I love how smooth the tuning is.