AM RECEIVER SUGGESTIONS & QUESTIONS

[n8yhy]

Hello to everyone.

  I have a few questions about some vintage Boatanchor Receivers and also maybe a few suggestions from those that know what BA receivers are good for AM operation..

 Well I have to start by saying I have had the chance to use a few different receivers for my AM station and I have to say I do really like how my National NC-300 performs specially now that I have performed a few good mod's on it which have consisted of converting the LC over to Crystal which greatly improved the selectivity and also the S-meter mod which has allowed me to be able to give a more accurate S-meter reading during my different Qso.. But I don't want to have to use the NC-300 for my different vintage Transmitters that I like to operate here..The NC-300 is paired up with my Valiant, but I am looking for something to put with my Ranger 1..I have used a HQ-170 and a SX-122 with the Ranger 1 station and well they aren't the greatest receivers in the world but I can't say they are the worst either..Any way I have decided to look for a better AM receiver and have looked at a few different one's such as the Collins 75A-3 & the 75A-4 and also the Hammarlund Sp-600 series receivers, I guess what I am after is something that is going to perform well on AM only, as I am not worried about how well it will  perform on SSB or CW. I am looking for a receiver that will have a little better rejection and selectivity and since I don't know everything there is to know about alot of the Vintage BA receivers I was hoping I could get some input from some of the more experienced AMers here.. I was reading the top ten and worst ten list about AM receivers and was sorta shocked when I seen what was said about the 75A-4 not being a great AM receiver,Which is what I was getting ready to purchase but after reading the top ten and worst ten i am not so sure now. I did have a chance to listen to a 75A-4 on SSB a few years ago and it sounded great but have never listened to one of AM phone so I don't know how well they do in AM operation.. I have heard alot of different fellows talk about using the Hammarlund SP-600 on AM and they say they perform great.I do have a R-390 which is just the plain R-390 not the 390A but it still has some work needed before it can be used and it will be a while before i can get this old BA operating 100% so in the mean time i want to purchase something that will be worth while to operate AM with.. So to get right down to the nitty gritty about the pro's and con's I need to hear from some that have been down this road before and knows alot more about the good AM BA's than I do..So if you have time and know more about some of the Vintage BA receivers and what's going to play well for AM please let me know your thoughts.I would greatly appreciate it..Thanks to everyone for taking the time to read this and thanks in advance for those of you that can contribute your input and thoughts..If you can just send your replies to N8YHY@SBCGLOBAL.NET 73 for now and Thanks Chris N8YHY

[Steve - WB3HUZ]

Read this.

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

[n8yhy]

Thanks for the Reply Steve but this is what I was referring to when I said I have read the Top Ten and Worst Ten list..

[Steve - WB3HUZ]

Sorry,, I missed that. I can vouch for the Super Pro 200, 400 and 600s. They are all great AM receivers, althouigh I think the 200 and 40 have superior audio due to the push-pull audio output. This radio will copy SSB after a fashion because they weren't design for SSB. The all have great IF bandwidths for AM to, allowing for good audio under quiet band conditions. The 200 and 400 have continuously variable IF BW from 3-16 kHz. Once you use that, you won't want to go back to fixed selectivities.

[W2VW]

It's hard to beat an R390A for on the air use.

[w3jn]

Chris, just becasue I don't like the 75A-4 doesn't mean others don't love theirs.  My article was not intended as an impartial guide.  The 75A-4 certainly isn't a BAD receiver as far as these things go - it's just an extremely poor value, especially for AM use.

However, given the present market, I don't think even the staunch defenders of the 75A-4 would maintain that there are better receivers out there for 1/4-1/2 the money.

And I agree 100% with HUZ.  The older SuperPro (SP100/110/200/400/ BC779/BC1004) is THE best value in a vintage AM receiver today.

73 John

[W3NP]

I have a Super Pro 210 and I love it on AM. I think you would do well with any of the pre 600 Pro's.  I now mainly use an R390A with external audio and I love my 390A's. I have a very nice 75A4 which I seldom use on AM because the audio is not that great and the 6 khz mechanical filter is somewhat narrow for good sounding AM. By the time you get a decent A4 and add the 6 kc filter you will see what JN meant by "not a great value". Yes, there are mods you can do to the A4 (check with Don K4KYV).... It all depends on what you are looking for. If really big sounding distortion free audio is not a big issue with you and you can afford it, the A4 is a great looking, accurate, and a fun to use receiver. I bought mine back in 1981 for $200 and used it as my main AM receiver for a long time....until I got an 390A. I also have a NC300 as well as a 303 and they are nice pieces. I sometimes use my Drake R8B with outboard audio and it does a fine job but they are pricey and just don't pair up with a BA xmtr that well.....too little .

Dave W3NP

[W1GFH]

Another vote for the SP210.  Hard to beat a RX that was designed (in part) for shortwave broadcast relay work (i.e. receiving full fidelity AM). These rigs were used in Hawaii to pick up Glenn Miller SW programs from San Francisco and beam them to troops fighting in the Pacific. The xtal filter and variable IF are very effective QRM-fighting tools for AM mode. Also when connected to a 12" speaker you have auditorium-filling sound levels and jukebox audio quality. OK, it's not "sexy" like a Collins....but the Super Pro's plain-Jane homely face will grow on you. A number of Super Pro's have been user-modified (e.g. audio stage gutted and replaced by 6AQ5), so try to get one that is as "stock" as possible.

NC300/303 are great all-around journeyman AM receivers with a lot of heart.

NC183's as well as HRO's have FB audio output, and were designed when AM was king.

SP600 would be perfection if it weren't for a slight lack of ballsiness in the audio stage.

Halli's such as SX-28, SX-88 make fabulous AM if you can find one for a decent price and not needing a lot of finicky restoration.

The R390 is a masterpiece, but not real user-friendly for casual tuning around and needs the outboard audio setup.

I hear tell R388's make decent AM once they are filtered out to 8kc.

I will chime in and reiterate that Collins 75A4's are nice rigs, but not great on AM, in stock mode they are restricted sounding, communications-audio, which is what Art designed them for.

[Pete, WA2CWA]

I love my Hammarlund SP-600 for band hopping, smooth tuning, and great audio.


And, if you have the room, get a bunch of them:

[n8yhy]

I want to thank everyone that took the time to reply to my post here and thanks so much for all the information about the diffrent receivers..Well it look's like my mind has been made up and i have made my Choice for a BA Receiver..THE SP-600 is what i am after..Now if i can find one that does'nt need completely restored..I'd love to find one that was Plug and play and I'd be willing to pay the money for it as well..So now the Hunt Begins..73 All Chris N8YHY

[GEORGE/W2AMR]

Some of my Favorites
 National  NC-170 NC183-D, NC-303,  Hammarlund HQ-180, HQ-150 , SP-400 

[kc2ifr]

I agree John.....I dont know why the A4 demands so much $......but for battle conditions I like the A4. Mine has 3, 6, and 9kc filters. The bandpass tuning is great and is the feature I like the best. My 390A is my overall fav.....followed by my NC303 and finally my SP600. I like em all I guess but they do have different features that makes it fun to mix and match.

[Jim, W5JO]

With all due respect to those who have answered, may I add my perspective?

As you age, you will loose your high frequency hearing.  You will only feel the low frequency.  So, being of an older ilk, I suggest you look at anything with respionse from 300 to 4 K cycles response.  Spend proportionally more on your speaker.

Many of the receivesr you can find will need attention to produce that response, but well worth it when you are my age.  HQ 140, National receivers with a tone control.

[Pete, WA2CWA]

With all due respect to those who have answered, may I add my perspective?

As you age, you will loose your high frequency hearing.  You will only feel the low frequency.  So, being of an older ilk, I suggest you look at anything with respionse from 300 to 4 K cycles response.  Spend proportionally more on your speaker.

Many of the receivesr you can find will need attention to produce that response, but well worth it when you are my age.  HQ 140, National receivers with a tone control.

Last summer I had some computer speakers with a sub-woofer hooked to a stereo amp that was fed through the detector output of the SP-600 JX17. When the thunder clapped, I ducked under the table. Had to stop using it though; it kept scaring the dogs.

[w3jn]

With the exception of perhaps the earlier Super Pros, ANY receiver will sound better routed thru a HIHIHIFI amplifier.

The SP-600 is a ballbuster to restore, and substandard bypass capacitors were used in many (if you have one with disc ceramic bypass caps you have it made in the shade - should be good to go for another 50 years).  No bandspread either, but the tuning rate is slow enough this isn't a real problem.  The earlier super pros are much easier to repair (there are a few bypass caps hiding in IF cans, but the covers are easily removed).

You're the one that has to be happy with it, so you should buy what appeals to you the most.  I'm just always amazed that people always seem to prefer the SP-600 over the SP-400, which is better for 160/75M AM usage IMHO.

As Bill said, there is also something to be said for having a battle-mode receiver when the QRM gets tough.  And the passband tuning, slot filter, and sharp mechanical filters in the 75A-4 make it one of the best for that (although if you have someone on the band that's REALLY strong, as during a contest, the front end kinda shrivels up and dies).

73 John

[W1GFH]

Hey wait a minute you picked the SP600 just cuz someone posted a picture of it. Take a lookit this SP200. It's a virtual "black crackle festival", for gawd's sake....

[John K5PRO]

I have been offered a NC-300 for nothing. It is DOA, but I could probably fix er up. Probably that ballast tube, as the guy says fuse is good, but no noise, nothing. Of course it could be HV dead too.

Anyway, I downloaded the book from BAMA, and it looks workable. The biggest problem I see is that the second LO was a design problem using LC oscillator, but that can be changed. Another is that the 300 has only a BFO for SSB, but I don't care about that, since I need it for AM quality. And yet another gripe I read about  is image rejection on the higher bands, like 20 meters.

My question is, is the audio response and output reasonable or upgradable? The book shows a rather rolled off audio response despite having decent IF selectivity curves for hi-fi. (not for adjacent interference though).

My other BA rx is a 75A3, which I don't like the sound of, but do like the frequency accuracy. It has a munged up mechanical filter for 6 KHz, unfortunately. The Collins is a lot more attractive looking than that National. Opinions?

[Vortex Joe - N3IBX]

Chris,
      You may want to consider a Hallicrafters SX-28; if you can find one for a "fair" price. There are other good receivers out there, but the SX-28 has long been one of my top favorites. 
Ditto on any of the Super-Pro receivers, especially the Super Pro 10. It uses a single 76 to drive a 42, which in turn drives a pair of (I believe)triode connected 42's for superb audio. The bandwidth is adjustable, etc. Out of all the SP's I like the #10 the best; but you can't go wrong with any "Super-Pro".

Best Regards,
                  Joe N3IBX

[W9GT]

Hi Chris, 

I would agree, for the most part, with the comments favoring the Super Pro series of Hammarlund receivers.  I particularly enjoyed the old SP-200/210 that I owned some years back.

Another suggestion is the good old National NC-2-40D.  Boy, those old receivers work great on AM and the audio is terrific, especially if you have the matching National speaker.  That push-pull audio really sounds great when receiving a good AM signal.  Same goes for the NC-183 and certainly the good old Hallicrafters SX-28.  All those receivers were quite popular when AM was the prevalent mode on the bands.  They offered reasonable selectivity and sensitivity, while providing really great sounding audio.  All of these receivers can be purchased quite reasonably.

I really love old St James Gray Collins stuff, but I agree that the 75A4 is certainly not the greatest AM receiver that I have heard/operated.  As for the best all-around performer, however, I still believe that the R-390A just about beats them all! 

Good luck with your quest. 

73,  Jack, W9GT

[David, K3TUE]

In the receivers forum ( http://amfone.net/Amforum/index.php?board=47.0 ) you will find 2 threads on 2 helpful articles reflecting 2 well-informed opinions.

Johnny Novice's Guide to receivers (which you have already seen):
http://amfone.net/Amforum/index.php?topic=4779.0
   http://amfone.net/ECSound/JNRECS.html

The Slab Bacon's "Receiver Road Test":
http://amfone.net/Amforum/index.php?topic=6059.0
   http://www.amwindow.org/tech/htm/slabrxreview.htm

[ve6pg]

...I KNOW THIS MAY APPEAR STRANGE,BUT FER SUM REASON MY HQ100 HAS INCREDIBLE AM AUDIO...I USE EQ,ETC ON THE OTHER RECEIVERS HERE,BUT THAT LITTLE '100 SOUNDS JUST GREAT...UNDERSTAND,THAT IS WHEN THE BANDS ARE NOT CROWDED,AND CANT COMPETE WITH QRM FROM OTHER STATIONS,BUT I'M SOLD ON THE STOCK AUDIO FROM THIS THING...MAKES ALL THE AM GANG SOUND GREAT...TIM..SK..

[Todd, KA1KAQ]

A lot of good info, Chris -

I have to say, this particular thread is quite rich in fact and thin in personal opinion - even if it seems otherwise. Exactly what you need for making a decision.

'JN, the 'HUZ and anyone else who is suggesting the earlier Super Pros is giving you the best advice for both AM audio and dollar value. And Joe 'IBX is right about the SX-28* models which not only sound excellent, they look like a true radio should. Unfortunately they tend to attract about twice the price of a SP-200 model in nice shape ($500 vs $250 or less). Of course, where you find one will make the difference in price.

Bill 'IFR and I were discussing the pros and cons of the 75A-4 on 160 t'udder night. The AM audio isn't too bad into a big speaker, considering the 6kcs limiting (and ringing) nature of the stock AM filter.    It's really designed mainly for SSB and includes AM/CW, so no big surprise. And this time of year it's especially hard to hear nice, broad AM audio through the static crashes and slopbucket stations anyhow, so the 'Battle Mode' features Bill mentions are handy and easy to employ. Just be prepared to spend some big bucks for a decent one if you buy online or from a collector. The earlier SPs are a much better deal and offer that nice variable IF along with their superior audio output.

What about the R-390? It's not as easy to find as the later, cost-reduced A models, but the original R-390 has somewhat better audio out than the A as a result of not having the mechanical filters. They usually cost a bit more than the A, and weight a fair amount more. But the R-390A is no slouch, and either one is a better value than the 75A-4. General coverage, too! Next to the SP-200/400, these are probably the next-best dollar value considering what you get. Plenty around.

The SP-600 and SX-28 have got to be two of the worst to get inside and work on effectively if you're doing a restoration. Well worth the effort, but expect to make up some new adjectives and nouns along the way.

John, I think the attraction to the '600 over the earlier SP models has to do with the 'band cruiser' ability of the big flywheel tuning knob, along with overall recognition to the average BA user. I'm sure glad you talked me into giving the SP-200s a better try, even more glad I had one in storage I'd forgotten about.

[w3jn]

Glad you put the '200 to work again, Todd!

John, a free NC-300 is nothing at all to sneeze at.  There are many who feel that is their favorite receiver.  If it's completely dead (pilot lites come on but nohting else happens) it's prolly the 4H4 ballast toob as you say.  A 6V6 makes a FB substitute, in fact that sub was recommended by National.

73 John

[David, K3TUE]

It is interesting that this topic was revived.  In re-reading it I find that there seems to be this wide-spread excitement about the pre-600 Hammarlund Super-Pros.

From what I can dig up, the differences between the SP-10/100/200 models seem to be little more than all glass tubes (SP-10), metal tubes in the front end (SP-100), and all metal tubes (SP-200).  I suspect that there were more modifications/upgrades over the life of this series, but I can't find much on it.

The SP-400 seems to be like the culmination of what was learned over the years of the SP-10/100/200 series, but I can not find out what makes it stand out above these other models other than it's huge power supply and it's relative newness.

Can anyone point out some impressions about what makes your favorite Hammarlund SP model stand out above the others?

[Todd, KA1KAQ]

From what I can dig up, the differences between the SP-10/100/200 models seem to be little more than all glass tubes (SP-10), metal tubes in the front end (SP-100), and all metal tubes (SP-200).  I suspect that there were more modifications/upgrades over the life of this series, but I can't find much on it.

The SP-400 seems to be like the culmination of what was learned over the years of the SP-10/100/200 series, but I can not find out what makes it stand out above these other models other than it's huge power supply and it's relative newness.

Can anyone point out some impressions about what makes your favorite Hammarlund SP model stand out above the others?

I haven't seen a '400 in person, so can't comment on the PS (I bet John can). My spin on the SP-400: it is to the SP-200 what the HQ-129 is to the '120, an updated/restyled version. I'd guess that it was a way to dress up an old pre-war design and get something "new" out to the masses post-war. IMHO, there wasn't a lot to improve upon in this design as it had pretty much run its course. For its day, it was *the* receiver to have, the SX-28 and HRO right along with it.

The '200 series has some pretty scroteful power supplies too. I think the mil version had an extra choke or...? I first saw the external supply as a nuisance for such a big box (there shoulda been plenty-o-room inside for it!), but later came to appreciate the potential noise generators being outside and away from the receiver.

In my renewed exuberance for the old Super Pros I did a bit of research. I'm sure you're aware of the different frequency variants in the 200 line. I found (from very limited samples and my fading memory) that the LF models had smooth semi-gloss front panels, sometimes gray on mil versions (some BC-779* as an example). Fine black wrinkle panel on the SX version. The only X model I've seen is online, and it appears to have a smooth black panel also.

As far as why I like the SP-200 family over the -600, it's easy: excellent audio in a very buzzardly box. Maybe it's not as interesting looking as an HRO or as cool looking as the SX-28, but it's not too bad. And yes - the filtering isn't as easy to adjust quickly when you're on the air as the 75A-4 is or as bulletproof. But it really is a great receiver, simple to work on with excellent results from minimal input. I hope 'JN offers more comments on it, he's had many more of them pass through his hands and has gotten into them a lot deeper than I have. When I told him my SX had some tubes changed to other types, he just rattled off what they probably were and why the mods were done. Damned if he wasn't right!

The early SPs remind me of Drake gear: very underpriced (thanks, collectors!) for what you get. The only thing more amazing is that I had several over the years and just passed them along without investigating further. Cheap, too.