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Heathkit AJ-41

nelsress

nelsress

Super Member
This past weekend I picked up a Heathkit AJ-41 tuner in very good to excellent condition and was wondering whether it was good enough to bother restoring or if it's just another beautiful, vintage, average performing tuner?

Along with it I got the manual too as the friend I bought it from was at the estate sale of the original purchaser/builder.

Below is a photo (sorry for the quality) that gives you somewhat of an idea of the condition. Is this a good tuner or just a beautiful, vintage collectible, or perhaps, neither? Thanks for any input from the more experienced tuner aficionados in our group.
 

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DSC_7320_zps0428d3fa by mhardy6647, on Flickr

beautiful? well, in the eye of the beholder, I suppose.

It is an OK tuner; not bad, not great. I have one but don't use it. I guess I keep it for its beauty ;-)

Worth restoring? How badly is it working as found? Worth a little sweat equity, I'd opine; FWIW, I wouldn't spend heavily on it -- how much incremental cost is sensible probably depends on how much you have invested in it (mine was a freebie). You might certainly feel differently, in all seriousness.

In fairness, it's nice that it has an onboard MPX detector.

Dollar for dollar, my opinion would be to source a Sherwood of the same era -- an S-3000IV (I think) or S-3000V has built in MPX stereo. They're every bit as beautiful, too! ;-)

Sherwood S3000 V 2 by mhardy6647, on Flickr

OK, the "V" is pretty homely :-P ... but these tuners sound fantastic, perform well as radios, and are (still?!) very inexpensive. Probably those cosmetics...
 
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Thanks, that's just what I needed to know. I've already got a tuner in my main system that, though nobody seems to rave about it, I like a lot. It's a Marantz 115B, sounds good, looks good, has variable muting which is handier than I thought it would be when I bought it, and picks up as many of the stations that I listen to as any other tuner I've ever had, just as well. Thanks again.
 
Absolutely keep this tuner! The manual is here:

http://www.vintage-radio.info/heathkit/

if you just scroll down. Look at what you get - cascode FM RF with separate oscillator, mixer and AFC tubes, 5 IF/limiter stages, Foster-Seeley discriminator, a good triple-tuned AM tuner with switchable IF bandwidth and a multiplex section that could be better but is certainly comparable to some of the decent ones.

The advantage of a Heathkit is the manual shows you exactly where everything is and why it was done the way it was. If you want to make changes, you don't have to hunt around - every item is in the manual. The specs may not be on a par with the best Scott or Sherwood tuners, but you have all the information you need to modify it to be better than it is and the specs seem to be conservative.

I have an AJ-32 that looks similar but is nowhere near as sophisticated - tetrodes for FM RF and autodyne mixer, 3 IF/limiter stages, ratio detector but a similar AM section and MPX and definitely not as good specs but it uses tuning eye tubes rather than meters for signal level indication.
 
Thanks, lots of good info-mhardy, you're a virtual treasure trove of Heathkit information! The information you provided indicates that this is, potentially at least, a very good tuner it seems to me. I'm curious though, you say you have one but don't use it, what tuner do you use as your main system?

Amptramp, thanks for pointing out the features you think make this tuner a keeper. I need to brush up on tuner info, I admit I'm lacking in that department. Soon I'll be putting up a 39' Rohn 25G antenna tower I hope to be able to use for FM as well as my TV antenna. I'm guessing that should improve my signal strength, etc. a good bit. Either that or it will just make the local megawatt country station appear across the entire dial!!!
 
One thing you will find with tube tuners in general is they are more sensitive than their solid state counterparts in most cases.

The "Stereo Phase" allows you the ability to adjust the channel separation. Use care around the "IF cans" as the one that is controlable via that control is unobtanium in most cases.

You can upgrade the quality of the resistors if you want to get that deep in it- and with the manual, why not? Granted, I am a little biased as I am a fan of what Heath was able to put out there, and have had some various pieces over the years and a few I kept as well.

Replace the filter caps before testing it, and then you can decide if you want to go into it further than just some cleaning of controls (LPS-1).
 
The nicest thing about a Heathkit is that you don't run into things that are not maintainable. Items are bolted together, not riveted or glued. These kits are a pleasure to modify, even though they use printed circuit boards.

For example, if you want better bass response (which it could use), C354 going from the detector to the mute circuit would be the first thing to increase. Now that you can get film capacitors in 2 µF and higher at respectable voltages, C339 in the multiplex section would be the next thing to replace. And a bit of extra capacitance in the power supply might improve the rather high hum and noise floor. Regulated oscillator voltages could reduce phase noise. The IF stages and the AM RF have rather high cathode resistors, good for low current drain but could be reduced for more gain.

You could go all out modifying this tuner to get performance comparable to a Scott or a Sherwood at a low cost.
 
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