specific receiver experience/impressions: Hammarlund SP-600-JX

[David, K3TUE]

Does anyone have any personal experience with/impressions of this receiver?  I have just been doing some reading, and was wondering if this croud had a opinions of it.

Mostly I just want to know what someone who knows them thinks of them.  Is it a receiver worth owning/using/keeping?  Does it have any notable of strengths and/or shortcomings?  Could you draw some comparisons with more well known receivers?

Just general stuff like this.

One thing I have noticed is that it is usually compared to the SP-400, which has enjoyed glowing praise.  Mostly what I have heard, aside from it's praises about being a smooth tuner/band cruiser, is that it does not have the fine 14w push-pull AF PA that the SP-400 has.  I was wondering if it is in any other ways less than the SP-400.  Does it have the same wonderful variable LC IF bandwidth that the SP-400 has, for example?  Are there any ways that it is better than the SP-400?

[w3jn]

Dave, maybe you want to make a thread for "receiver impressions"... are you considering buying a receiver?

The SP-600 does NOT have the continuously variable IF that the earlier Super Pros have.  It has 3 non-crystal selectivity positions plus 3 crystal selectivity positions.

It is much more difficult than average to repair/recap, and they are usually liberally strewn with black beauty caps that will most likely be leaking.  RF performance, especially on the higher bands, is better than the earlier super-pros; it is double conversion so the image rejection is MUCH better.

The SP-600 is more stable than the earlier Super Pros but only has a single ended 6V6 audio output.  It's a true joy to tune around, much better than the SP-400 et. al.  The power supply appears to be the weak point in the SP-600.

ANother advantage the SP-600 has is that the power supply is internal rather than an external 'cat coffin' like the earlier super pros.  Of course that earlier PS was absolutely bulletproof... never seen a bad original component (including capacitors) in any of the ones I've had.

73 John

[WA3VJB]

Yeah Dave, I agree with John's point to start a receiver impressions thread since you're clearly shopping, and a number of people could later tap the archived answers. Meantime you can expedite your accumulation of knowledge with simple Google searches, which would tell you about the differences among SP600, 400 and 200 variants to start with.

To the SP600:

http://www.aa9tt.com/Hammarlund/hammarlund.html

Here's another site, however it is a bit irritating because of its TYPE FONT FOR THE HARD OF SEEING and a cumbersome number of theatrical click-throughs to get to the information.


http://www.hammarlund.info/sp600.html


I've had an SP600 JX-17 for a couple of years now and I like it a lot.
It came with ceramic rather than "black beauty" type capacitors, and while it has seen a lot of use, it remains solid.

For audio quality, I use the diode output rather than the internal audio circuitry. It's much cleaner and has a flatter response. Use a DC blocking capacitor and drive your house audio system that you would configure with music-quality speakers and a hi-fi amplifier (the point is to avoid communications-type "public address" components).

The selectivity setting that I use most often is the 10Kc, non xtal bandwidth. This works well for listening during uncongested times on 75m, and more typically can be used comfortably on 40m, 15m and 10m.

Tuning is VERY nice, with the flywheel momentum velvety smooth dial.

During times of congestion, however, you would do much better with an R390A or its older sister the R390. Not only are there more options as to selectivity, but if you really need to pinch one, the mechanical filters of the 390A can't be beat.  Fidelity is preserved by again using the DIODE output available on both of these receivers, as with the SP600.

Good luck in your search.

[Todd, KA1KAQ]

Another thing the SP-600 is/was notorious for is drift. My first one wandered all over the place until Les Locklear told me about the multiple taps on the power transformer. Moving it up to the next tap (125v from 115v I think) made all of the difference. The receiver settled down nicely, and after a 15-30 minute warmup time stayed put. This was the first thing I checked on the one I have now.

They are indeed a joy to tune with that big flywheel and all the nice gearing. If you get one, be very careful about over-lubricating it since the tiniest amount of oil on the edge of the tuning dial will cause it to slip. If you get one with this problem, clean off all of the brass along the dial edges, gears, etc with some alcohol. This should correct it. Very few points in the tuning actually need any lubrication, but when folks see all of those gears they tend to be overly generous with the lube.

The turret tuning, while a clever idea at the time, makes some servicing a bear. As 'JN mentioned, earlier (probably most) models used caps that are often found to be cracked and "leaky" in the physical sense, as well as electrically. Later models used mainly ceramic disk and mica caps. Found one of these for John Flood a couple years ago at Hopkinton for $275, a cheap price when you consider the maintenance saved and overall improvement of operation.

Beyond that I'd add that as Paul mentioned, stock audio through a speaker leaves something to be desired. Many of these older rigs were designed for government or military use where audio fidelity wasn't the issue. And the dial readout/accuracy could be better, but it is an old radio after all.    BFO might be on the anemic side as well but some component replacement should cure this. Overall it's a great receiver to use and enjoy if properly serviced and set up. Mine sits in a rack right beneath the R-390 and R-390A for use as a search receiver. Problem is, I usually end up just listening to it instead of switching to either of the other rigs.

[K1MVP]

Hi Dave,
I agree with Todd,(KA1KAQ) the turrent assembly makes this receiver a
"pain" to work on, if there are any shorted coupling caps in the "front end".
I worked on one a number of years ago, that a guy gave me cause it had
a burnt out power transformer,--reason was the receiver had 2 or 3
shorted plate bypass caps in the I.F. section, and after I replaced those
smoke started coming from the "front end".
After "lifting" the front end assy(which was a real pain) I found shorted
coupling caps, with the net result that some resistors were burnt.
After replacing(the caps and resistors) very carefully,--and replacing the
power transformer,--the receiver "came alive" and worked great.
Its a real nice receiver,(real sensitive and great audio) and makes a great
"band cruiser".
It`s also a "heavyweight", so if you have a good back you will be ok.

                                       73`s,  K1MVP
 

[Vortex Joe - N3IBX]

David,
       I have a SP-600-JX1 of the first production run, and it performs very well. Like JN mentioned, the audio isn't as good as the Super-Pros' that had push-pull audio output or the variable "Lamb type" filter, but it seems to have special qualities all of it's own. The SP-600 is the most modern variant of Super-Pro and in general a very good receiver. The later variants (17,24, etc) tend to bring more money than the earlier variants, but I don't know if there is a big difference in performance between them.

In comparing a SP-600 to other upscale receivers, It's kind of hard to say what one would compare it's performance to. Perhaps a Collins R-388 or 51J without the 1khz frequency resolution.

It's just my opinion that if you acquire a nice SP-600, you won't be dissapointed in it's performance.

Best regards and good luck with whatever you happen to acquire.
Joe Cro N3IBX

[Steve - WB3HUZ]

Although the SP-600 doesn't produce audio quality to the level the SP-200 or 400 series, it's not bad stock.




Here you can see the response of JUST the audio amp itself [The IF bandwidths are not involved. You will see they roll off the high end in the next plot.] The biggest weakness is in the low end. But with just a few cap changes, the low end response can be made flat or nearly so to at least 100 Hz. I made the mods from the URL below on mine (just the coupling and bypass caps changes, I skipped the resistor changes), and took frequency response measurements. But I never got around to plotting them. According to Al, N3FRQ, adding a negative feedback loop from the output tranny back to the first AF amp will flatten out the response on the low end down to 50 Hz or so.

http://www.amwindow.org/tech/htm/sp600aud.htm

In the plot below, you can see how the IF bandwidth begins to play in rolling off the high frequency response. As you can see, you can get about 6.5 or 7 kHz of high end response out of the SP-600. With the 200 or 400 series, the high end response would be 8 kHz or so because the IF can be opened up to 16 kHz. The importance of  this relatively slight difference can only be determined by your taste/ear and or operating habits.




Get full sized images of the plots here.

http://www.amwindow.org/misc/gif/sp600/af_plots.gif
http://www.amwindow.org/misc/gif/sp600/if_bw_plots.gif

[David, K3TUE]

Dave, maybe you want to make a thread for "receiver impressions" [...]

I would, but I guess I was being self-serving.  A while back I asked for some info on general receiver impressions, then I asked some more pointed questions.  And to keep the impressions more specific I thought I would ask these questions in separate threads.  I guess I thought that if people were interested in the receiver I was aksing about then they could more easily just follow a specific thread.

[...] are you considering buying a receiver?

Not right now, I'm not.  I bought an R-8B recently  (the XYL almost demanded that I spend the money on it).  And I recenly replaced my bedside RX, a Palstar R30C (with SP30 external speaker (a la Drake) and AA30 preamp), with an SW-8.  The Palstar is a wonderful and simple modern RX that helped me get back into amateur radio.  But the SW-8 has a nice synchro-AM, BCB AM and FM (which knocks the bedroom radio count in the down to 1), and it's all in one cabinet and still sounds nice (not as nice as the external speaker, but still nice enough for the bedroom).  So I can't justify another receiver right now (but perhaps soon :-).

I just love reading about so many of these old receivers.  I can't wait until personal obligations allow me the time and money to actually buy and tear into some of them.  I have actually been doing a bit of transmitter evaluation lately.  But that will be a discussion for another thread.