The AM Forum

Hammarlund superpro 200, RCA ar-88 , hallicrafters sx-28. Those receivers where available in the surplus market after war. Which is the best and why for ham use for your opinion? And for military intelligence which was considered more versatile, and with better performance? I have my opinion but i will teologicamente you later.

I vote for the Hammy SP-200. 8) 

The RCA 88 wasn't much different circuitwise from the Hammy HQ-120/129: good but the bargain model.

SX-28's were pretty, but didn't have the build quality of the SP-200 IMO.

73dg

I own all three and I have the same ranking as TFO.  The SP-200 build quality and performance is quite good.  Be careful which model you get if 160 meter coverage is important to you as the low frequency version is common and covers LF and then starts coverage again at 2.5 Mhz covering through 20 Mhz.

I like the AR-88 a lot and I think it comes pretty close to the Super Pro in performance.  The SX-28 is definitely competent and to me has THE classic vintage gear but doesn't quite compare with the other two.  But it is certainly no slouch.

If you rank them in terms of physical attractiveness then the order is reversed with Halli at the top.

Id vote for the HRO ;)  Military inteligence thought highly about it and the Germans and Japs actually copied it.

The SP-200 is very noisy above about 12 MHz due to the tubes used in the front end. They drift bad. The variable IF selectivity is a plus. No BS calibration. Lots of audio from PP triode connected 6K6's. PS is often hard to find.

The AR-88 is not ham friendly due to no BS calibration and no external crystal filter phasing control but makes an excellent SWL radio. Wimpy single 6K6 audio. Very stable and sensitive. The peak years of RCA.  Replacement parts are getting hard to find.

The SX-28A when new or restored is very sensitive and fairly stable. It is still considered an excellent ham receiver but a bit of a PITA to rebuild.

Others to consider are the US Navy RBB and RBC, arguably the best WW2 military receivers ever built and a somewhat well kept secret. You need both to cover 160-12M and the tuning stops at 27MHz. Most work excellent as found.

Ive owned and sold a couple of military SP-200's, tried an AR-88. I now own a pair of SX-28's and a RBB/RBC....those are keepers along with a couple of HRO's.

Carl

SP-200, especially if it's a civilian black-crinkle job.

Keeping it back on track "of the three", the Halli power transformer is a known weakness the other two don't normally suffer from.

The 88 IS a good-looking set, but not for me.

73DG

Home of 20 some-odd Hammys in the Southwest

 Of the THREE listed, I too would put the Hammarlund at #1 spot actually by a pretty good margin. I must note however that my exposure to the RCA is limited. Although the 200 lacking in stability perhaps, the SX28 is not exactly a PLL either. The 200's variable selectivity works pretty darn well and the audio is great.
  The outboard power supply has  advantages , many come with homebrew supplies . The SX-28 power transformers are marginal and prone to failure. The Hammarlund is also a lot easier to service in most cases . The SX-28 noise limiter however is a real gem ! And looks are subjective but the SX28 is a fine looker .
 

My Superpro is a modded version with power supply on board ad product detector, so i cannot really compare it with the plain one. I can say that the stability is good, but after half an hour or better 1 hour of warming. The sensibility is very nice up to 20 meters band but this receivers arrive only at 20 mhz. The selectivity is good too, with a lot of christal positions and the continuous variable LC filters. What i really don't like is that i cannot tune a certain frequency if i don't know how to set main tuning and the band spread. So to tune a precise frequency i need a calibrated trasmitter or a signal generator. The AM reception is very good There is no tone setting. The look of the receiver is quite ugly .

My sx-28 is more stable in the short period. The drift is almost inexistent after 10 minutes. The look is fantastic and maybe one of the best looking vintage receiver.
the 6 level of selectivity are good, but a little less efficient that the superpro .
There is a good hifi tone control and bass enhancement. A very good feature of the sx-28 is the calibrated band spread for ham bands , it works great and the tuning in incredibly accurate. The sensitivity is good, also on 10 meters !! the receiver is really hot, but in 40 meters in the evening there is some intermodulation from the BC stations if i leave the rf gain at maximum. The superpro is not prone to this problem.

I will test the AR-88 this weekend. A friend with a very good lab has totally aligned my receiver after changing some bad caps and resistors and he told me that now exceedes the performance in the manual charts.

Wow,
        What a tough call!! I would vote for the 28 or the super pro. The 28 is just an incredible receiver for the era when it was built. Especially with the 6SK7 IF amp tube swapped out to a 6AB7!! The signal to noise ratio is incredible. My only complaint about a 28 is the wimpy BFO.

The SP-200 is pretty much as high end as it got in those days, But it doesn't have a calibrated bandspread.

I have owned and operated both of them, (and an AR-88 as well). All are good performing receivers for their day, but, I have to lean towards the SX-28 for AM use.
(Seeing that I sold the Super Pro and the AR-88 and kept the SX-28)

Now, if I had to cull the herd down to just 1 receiver, that would be another tough question. (I had 17 at one time) I think it would be a souped up R-390 or 390A.

But, I don't, so I won't.  ;D  ;D  ;D

 Funny, I had many R-390s and 390a .OK for SWLing but I needed a bit more from them for fighting QRM. Didn't really care for the ergonomics either. I did have a pair of R-725 that I kept around for SWling but did not care to use them on the ham bands  . The R-725 offered the best aspects of the two IMHO. I liked the sound of the fine LC filters far better than the Magneto-Mechanical contraptions. Both were modded with push pull audio , a worthwhile improvement. Never cared for outboard amps compared to the modded internal amplifier , maintaining front panel control.

 The toss up between the Hammarlund and Hallicrafters is understandable. A matter of personal weighting of the different characteristics. Of course modifications are a wild card beyond the scope probably of an I-net forum. I would like some day to try out the AR-88 but sadly have not seen many available in this are. Joe, W8UVS is the only local guy I know using one and he seems to like it. I recall Ozona Bob raving about his AR-77 but, like the R-390/390A/725 it is not on the list .

There is nothing wrong with the SX-28 PS that a little common sense wouldnt cure. If people would quit trying to run them without a full recap or believe in a reforming the electrolytics fairy tale they wouldnt fail. I also run all my tube gear at 109-115 VAC with bucking transformers.

It doesnt take much to make the 28 ready for todays bands. The first step is to toss the 6AB7, 6SK7 and 6SA7 front end and replace with a 6SG7, 6SG7, 6SB7Y. The 6AB7 is the primary overload culprit and was used after the first few production runs to improve sensitivity. Rather than bother selecting voltage parameters for the 2nd 6SG7 gain, build an external switched step attenuator or buy an old 60's lab style.

The SP-200 doesnt overload because it is comparitively deaf and not surprising due to its mid 30's design. There was a good reason for stopping at 20MHz. It would also benefit with some simple tube upgrades. Once I get serious about the SP-400X here I'll do a full report on before and after upgrade performance....see Im not really anti Super Pro :P

Sticking with the WW2 theme all can benefit by running the IF into a BC-453 modified for AGC as well as a product detector. The low level audio can be fed back into the main radio if desired.

Another option is to add the KIWA IF filter/vacuum tube interface under the chassis to improve the skirt selectivity which is rather poor on most all 455/465 kc IF radios prior to mechanical and packaged crystal filter designs.

I'll admit doing both the above to a few sets as well as adding a CE B Slicer or HC-10.

Carl

 Never lost a transformer in an SX28 personally. Then again never lost a tranny in any of my BA receivers. The only electrolytic failure I have had was a bias filter in a 183D that had been replaced with a modern cap by the PO.

  Both of the supplies for my SP200s came with oil caps, no electrolytic concerns there.

  Does seem like I have seen quite a few 28s with new transformers, not uncommon with many H'crafters products. Even transmitters with oil caps. Nothing conclusive and I won't play the elitist and blame owners as the same owners may have different results from different makes.

  As noted, modified radios are a different animal and probably really outside the THREE that we were given to choose from.

  IF I had to cull down to 1 receiver for amateur use , it would not be any one of those three  ;D (The R-390/A/R-725)would not make the list either )

Carl... thats interesting.... my full recapped sx-28 is very sensible, maybe too much... and on very strong BC signals with rf gain at maximum i can ear some distortion for too much signal... i have the 6AB7 tubes in my front-end maybe the receiver holds better with the less gain of 6sk7?
or i have just to replace them with 6sg7/6sb7y? are those tubes plug & play?

If you want a 50-60's receiver, just get one. Modding the 30's radios seems a waste.

Yep, I have restored several pre-war Hammy SP's and HQ's that folks just couldn't leave well enough alone.  Butchered chassis with mini tubes, power supply shenanigans, extra controls, you name it

A simple neg temp cap in the osc section and they don't drift.

Feed them with a high-impedance balanced antenna (as they were designed for) and they are hardly 'deaf' anywhere on the dial.  The S/N ratio goes to your favor and becomes very quiet internally.

73DG

  Yes, EXACTLY,  ;)

This applies to any of the three mentioned

Try the 6SK7 first, if the loss in sensitivity is too much for you use a 6SG7. While typical operating parameters differ a little a direct swap works well.
The 6SB7Y is a direct swap, lower noise and less overload, it was developed for the old 40-50MHz USA FM broadcast band. National and Hallicrafters used it sparingly as it was more expensive than the 6SA7. Many will remember how sensitive the very basic NC-57 was with a 6SG7/6SB7Y front end.


Not to all. I for one enjoy actually using them and have them grouped by era. Some have simple no holes mods and others go to the originality extreme of restuffing caps and replicating resistors.

I like the SX-28 for SWL and ham use. It is not the most perfect receiver for demanding situations but the sound quality makes it easy to listen for hours and it is easy to tune.

The AR-88 is a ball/back buster weighing in @ 100 lbs.

The other two are only in the 70 lb. range.

Yet one of the big pastimes on here is discussing and doing audio and other mods to just about every transmitter built and nobody complains and the better mods work well.

OTOH, let somebody change a tube socket in a receiver and the crybabies are out in force.  I'll tell you what: you do things your own way and mind your own business when others do it their way. OK?

'I'll tell you what: you do things your own way and mind your own business when others do it their way. OK?"

Sounds like an imperative to me, boys.  You all got that?

Hup, two, three....

73DG

I'm pretty sure no one is telling anyone what to do here. If you want to paint your prewar receiver neon pink and put spinners on it, knock yourself out. If you feel that emphatic about it, why would you care what anyone else thinks?

As far as the transmitter mods, I think many of them are a waste too. Some amount to trying to fit 10 pounds in a 5 pound bag. After a certain point of modification, it would easier to build your own or do it outboard.

That said, much can be learned from doing even overkill (IMO) mods, so I'm not totally against them. I do see messing with the more rare pre-war receivers different than messing with a rather common 50-60s transmitter like a DX-100, etc.

As always, YMMV.

I'm waiting for a big batch job to finish running.  Not directed at anyone here, but I can't get over the collector fanatics who have to have everything pure and original but historically, some joe ham who owned their rig originally probably thought nothing of substituting whatever he had on hand to perform a fix.  to that end, I believe an old tx or rx with some original owner mods, because maybe he couldn't get the OEM genuwine part, is more historical.  Of course it depends on the part and the modification, but these guys who get bent out of shape over adding a product detector need to step back and take a breather.

With not that many 30's commercial transmitters surviving its more a matter of actually getting parts to make them work again, home brew was king then.

There arent any worthwhile mods for a HT-9 which is about the only prewar rig Ive seen in some quantity along with the various flea power, plug in coil, Signal Shifters. The WW2 ART-13 is always being modded.

With pre WW2 receivers in general going thru the "golden years" of radio, sets were obsolete the year of production and hams were always trying to upgrade them. Magazines were full of modification articles and the manufacturers had engineers regularly writing feature articles. At National they even did it for you if you wanted so finding a 1935 HRO or other glass tube model with HRO-5/5A1 features is not that uncommon. Other models with eye tubes had new panels with S meters done at the factory or sold as kits. Im sure some "restorer" has stained his panties and returned it to as built meanwhile whining about hammy mods.

While I wouldnt touch the AGS-X, FB-XA or the Run 1 HRO, Run 1 SX-9, SX-23 and a few others I had no problem making no holes reversible changes to the NC-101X, NC-200, SX-17, SX-28, HQ-120X as these are in regular use and cycled thru the operating positions. Certain postwar sets are also modified. I also operate CW and SSB  :o and I dont limit my life to the depths of 75 for AM; several on here have worked or heard me as high as 10M for the HF bands when Ive been using 30's and 40's receivers with souped up front ends.

Carl

 Which of the three?!
Hammarlund superpro 200, RCA ar-88 , hallicrafters sx-28.