The AM Forum

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

Read this.

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

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..

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.

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

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

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

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.

I love my Hammarlund SP-600 for band hopping, smooth tuning, and great audio.
(http://perso.wanadoo.fr/radiomos/Militaires/SP600/SP600_R274A_encabinet_h.jpg)

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

(http://www.pinetreeline.org/photos/stephe/steph234.jpg)

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

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

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.

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.

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

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....

(http://www.radioblvd.com/hamgear/nusp200.jpg)

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?

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

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

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

...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..

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.

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

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?

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.

The stock 75A4 may not be the greatest AM receiver out there for to-day's money, but it performs superbly under piss-beat QRM condx, and I  like the freq stability, dial readout accuracy/resetability, i.f. notch filter and passband tuning feature.  I was able to solve the front-end overload problem by inserting an outboard homebrew switchable 20 dB attenuator pad in the antenna line.  With some antennas I run the attenuator in line all the time and still have plenty of sensitivity.  I think that's the problem - Collins tried to build in too much front-end sensitivity.

Like the R-390A, the shortcomings in the audio can be overcome with an external audio amp and good speaker, but a  couple of simple mods must be performed unless you pick the audio right off the diode  load.  There is a test point on the the chassis you can use for access to the diode load if you wish.

To me, what places the 'A4 low on the  list of AM receivers is the present-day inflated price, driven up by the trophy collectors who pay big bux and never even plan to actually use the receiver.

I would say it is an excellent choice if you can find one in the <$400 range, and you are willing to bridge additional capacitance across a couple of coupling caps and clip out a couple of "hyellofying" caps.  I put (appropriately reversible) mods in almost almost all my stuff anyway, so to me the 'A4 mods were no big deal and pretty much routine for my station.

I have two 'A4's.  Bought both back in the early 1980's.  Paid $200 for one, and $100 for the second.  The second even had a full array of filters, including  the stock Collins 6 kc/s one.  The downside to that one was that a previous owner had completely wrecked the spinner knob and vernier tuning mechanism.  But I was lucky to find a nos, in unopened box, Collins conversion kit complete with mechanism and new spinner knob,  plus instructions on how to install it - the whole thing for $35!

To-day that kit would go to a trophy collector for more than I paid for both receivers combined (even with price corrected for inflation), and like the unbuilt Heathkits, the buyer would likely never dare even remove the first staple from the factory sealed plastic bag it was packed in.

As for Super-Pro's, with the pushpull audio stage, they are great if you can keep them working properly, and plan to use them strictly for AM, and never attempt to listen in cw or ssb modes.  The main drawback is that the frequency stability sucks!  The reason is that the basic mechanical design of the main tuning capacitor assembly makes it prone to thermal expansion/contraction.  The second drawback is that some parts of the circuitry are extremely hard to work on - particularly the rf amplifier and mixer subassembly.  It is practically impossible to gain access to some of the components to replace them - particularly those plastic moulded paper caps that you will usually find leaking an oily residue.

The problem I have with the R-388/51J series is the 500 kc/s i.f. stage.  It is extremely difficult to find replacement filters for even the stock selectivities, let alone wider bandpass such as 8 kc/s or higher. So you are pretty well stuck with restricted, 6 kc/s selectivity in the mechanical filtered models.

Dave,
       The reasons why the Super-Pro 10 is my favorite in the SP line:
  
       1) The high fidelity PP 42 audio outpoot is fantastic
       2) Very Oldbuzzardly and kewl looking (The SP-10 dates to late 1935,early 1936. Some like mine, even had an 8 ohm audio output)
       3) Good adjustable selectivity
      
A drawback: The "R" Meter reads backwards and is only a general indicator of received signal strength.

As a point of reference: Don't quote me on this, but I believe there were something like 26 "JX-" variants of the SP-600. Regardless of which one you have, they're all quite good, though very different from the SP-10,100 etc series; and have a built in power supply. I have one of the very first SP-600's, a low serial# "JX-1" built in August, 1951. It's performance seems identical to a "JX-17" I owned 20 years ago.

Regards,
          Joe N3IBX

Yep. That black-crackle SP-200 is one of the prettiest RXs ever made, IMHO. And the audio on AM is killer. Wish I still had one. Instead I have a 400, with tan crinkle and less cool looking knobs. Still killer audio though.

I was guilty of pulling up this old subject here and adding my comments yesterday, about the NC-300 I am about to get. I have the 75A3 now. The previous postings were Sept 2005, so a lot of you are replying back to that information I fear. I should have just opened a new topic, but this one seemed appropiate to ask my questions. thanks for all the comments.

Well, some new questions have been asked.

Don, at $400 a 75A-4 is an outstanding buy for one of the best battle-mode radios ever made.  Keep the front end attenuator and external audio amp handy though!  As others have pointed out the thing I have against the 75A-4 the most is that it's a very poor value for a receiver nowadays.

The SP200/400 series can be made more stable by (a) centering the variable cap plates (loosen the locknut on the end of each cap, and carefully adjust in or out with a screwdriver for a peak or dip when BFOed against a carrier) and (b) cleaning the wipers on the oscillator section of the variable capacitor.

The older SP-series isn't nearly as hateful to work on as the SP-600.  The caps in the RF compartment are a bit of a bother, but they're at least accessible if you have a small dikes and a soldering iron with a long tip.  More than I can say for an SX-28....

The PS on a SP-400 is a bit smaller than the BC-779/BC1004 power supplies.  It's a "cat coffin" design rather like a larger HP23, rather than a huge rack mount affair like the BC-779/BC1004 PS.  The military PS has a bunch of oil caps for filters vs electrolytics in the SP-400.

The SP series is very easy to align despite the variable IF selectivity (watch for B+ on the trimmer caps in the IF cans!!) and once set on the proper IF frequency the readout is dead nuts on, in my experience.  Many hams love to align them on 455 KC for some reason instead of the required 465 KC.

The things I don't like about the pre-600 SPs:

1)  Tuning not as smooth as a SP-600
2)  A UL nightmare... high voltage exposed everywhere on the rear panel, and high voltage on the trimmer cap screws
3)  If the on/off switch carps out you gotta remove the RF deck to remove it.

73 John

The real issue on 20M is feedthrough of an image of one of the SWBC bands.  Daytime no problem, but when that band is open at night you hear a lot of it all over 20M.  There is a simple adjustable 9.7 Mhz mixer trap circuit, but it isn't all that effective.  This is true on both the 300 and 303, although it seems to be worse on my 303 than on a 300 I once had.  The radio really needs a band-reject or high-pass filter in front of it.

Oddly, this trap circuit isn't even mentioned in the 303 manual, although it is present in both radios.

Except for this image issue, the 303 is one of my favorite radios, especially with the audio tapped off the detector output and fed to an external amp.  Mostly because I love that big slide-rule dial  :)

I was planing on making a power panel screw cover plate of hard plastic tubing,
but which trimmer caps are you referring to - where?

Jeez, nice necro  ;D

The IF trimmers on the plate side are hot with B+.  Use an insulated screwdriver here.

Originally there were covers over the exposed terminals on the back of the SP-200/400 series radio and PS but these were lost in most cases.  Of the 4 that I have only two came with their proper covers; 1 was covered with electrical tape and the 4'th was bare.  Still not as bad as the Hallicrafters HT-19 (NBFM and CW with a 4-65 final) which brings the plate and screen to voltages to open binding posts on the back for easy hookup of an external modulator.  I built Plexiglas covers for mine since having a set of 1,750 volt plate supply terminals uncovered on the panel didn't seem like a great idea.

The SP-200/400 do sound nice on AM.  My favorite all around AM receivers are the from the Hallicrafters SX-100 family (100,101,115,117).  They have enough bandwidth to sound good when conditions permit and narrower choices are available when needed and my favorite feature is the selectable sideband on AM which often allows SSB QRM to be removed by switching sidebands.  The HQ-170/180 also have this ability to select sidebands but the audio isn't as good and unlike many others I actually like the Heathkit RX-1 which also provides selectable sideband.  I have a couple of RX-1's and as long as the IF gain is reduced to a reasonable level it sounds pretty good.   

Over the weekend I realized how much I missed being able to easily choose the best sideband to avoid QRM.  Right now my main AM rigs are a Ranger/Desk KW with an SX-88 and a Viking 500 paired with a Pierson KP-81.  The Pierson has good selectivity from its multi-stage 455 Khz IF and the SX-88 provides very nice selectivity from its low 50 Khz. final IF but neither provides the ease of switch selectable sideband and both require retuning to provide this performance.

Do you love it?  Did you have one when you were younger?  Did you want one but couldn't afford it?  Did your buddy across town have one and you wished you did?  Was it the receiver at the high school radio club?

Those are as important as the specifications.  Almost anything is good enough for rag chewing.  For awhile I was using an NC-270 because it was the receiver at the Benner Junior High School station and as cute as a button. I used an NC-125 because it was my novice receiver and a 75S-3C because I used to drool over the pictures in the handbook, etc.

One more important consideration.  Do you really want to lift it?  I have an SX-28 which is heavy enough but I've managed to resist getting an AR-88 because I figured I'd end up in a back brace.

-- Jon

PS: Receivers I actually use the most?  74A-4, SX-28, R4-C and (horrors) Ten-Tec Omni VII. The R4-C with Sherwood audio & PS, no 6 KC filter (straight through)  is a killer receiver for AM, CW & SSB even though it doesn't weigh much.

I'm still a fan of the SP-200, although mine has developed some weird warm-up symptoms lately, it is terrific if you like the classic AM hi-fi sound. Yes, exposed power terminals are a bit sporty. If anyone has some plexi covers for sale, let me know.

(Hiya Jon/JEK. Yup, the "2nd best sounding Ranger on the West Coast" has moved to a Boston suburb. Check out pix of the new W1GFH slimmed-down, "Johnny Novice In The Basement" shack - attached)

Good looking essential shack.  Now that you're out of the neighborhood I'm willing to concede that you actually had the best sounding Ranger on the West Coast even though Bob Heil gave mine the title.  He was drinking champagne at No Money's place.  But weren't you using some fancy schmanz microphone and audio set up?

You got it right, that was the night Bob Heil reportedly snatched KO6NM's RE-27 off the stand and threw it into the swimming pool. From then on, all the So Cal "big guns" switched over to Heil PR 40's.


Yup, big voodoo: a cheapo Marshall condenser and ART EQ into the mic input.

Let me chime in regarding the 75A4 on AM, even though it's a bit late. Mine came with an old homebrew IF filter substitute constructed long ago. It sounds terrific. I have made the few audio changes Don suggests, well worthwhile IMHO if you use the internal audio stages.

But about the IF filters... I have had both the original Collins and the current aftermarket. They are OK, good for battlemode, but under quiet band conditions the old LC filter is way better sounding. The one I have uses a miniature IF transformer. It seems to be about 12 Khz or so... never measured it. There was another version using two miniature IF cans I saw somewhere. It may have been in an old CQ magazine. Both of these were published long ago but seem to have been forgotten about?

I ended up using this filter lineup: Collins 3Khz, aftermarket 6Khz, and the homebrewed 'wide' LC.

The LC filter sounds way cleaner... not extended in response as much as just cleaner. Maybe this is what is referred to as ringing in the R390a vs R390. But if anyone attached to their 75A4 is curious I strongly suggest giving it a try - whether you use the internal AF stages or external amp.

On the selectable sideband QRM dodging technique: The Hallicrafters SX 115 offered this as the only AM receiving mode, probably due to the low last IF. Normal AM reception is carrier and either sideband, out to 5 KHz (for a 10 KHz equivalent mode). Not a shabby receiver at all, for either AM, SSB, or CW. It was supposed to compete with 75A4.

 

Fred,
      Is the 6KHZ filter in your A4 a aftermarket mechanical or a xtal job? I'm curious. Also, how would you compare the aftermarket mechanical filters to the original Collins branded one? I'd think they're both about equal, but maybe not due to advances in technology since the original Collins filter was designed.

I have a 75A-4A that I'm very much in love with. It's the very best "battle conditions" receiver I own. I mated it to a 32V-2, and use the pair on the aether once in a while, especially when the going gets tough.

Mod-U-Later,
                Joe Cro N3IBX

I had a SP-200 some years ago, complete with the rear term.strip covers, but traded it off.  ...sigh...  If I recall correctly the power cable was cloth covered.  Neat thing about the 200 was the sliding eyeshutter for each band.  way cool.
About the audio, the driver transformer was the same size as the output transformer.  How could you go wrong?... 

Tim mentioned -

I guess good sound is in the ear of the beholder...  8).  We've probably beat it to death in other threads, but that's gotta be the effect of those cool couplets and feedback circuit Hammarlund used.  The higher the volume the tighter the audio bandwidth. 

At strong BC shortwave station level, one has more than enough audio to enjoy full audio bandwidth (vol. control at min. levels.)   I wonder if a better AVC would negate the 'variable' audio bandwidth characteristics.  Almost have to if all the audio is presented to the AF amps at the same level.   But Hammarlund put that circuit in the HQ100 and 110 and from my experience with a 110 it worked well enough to be noticable.

I have an HQ-110.    For AM operation, the narrowing of the audio bandwidth will never happen at normal audio levels.    For SSB or CW, you can turn the audio all the way up and use the RF gain control,  you will then notice the decrease in audio bandwidth that is more useful for those modes.   I also have an HQ-140X, which I believe is a better receiver for AM when signals are closer together.   Also have an NC-183, which sounds the best for AM when connected to a HIFI speaker, due to its 10W push-pull audio output stage.    On 10M I like the HQ-110 because of its dual conversion and no images.