[Heathkit] SB-301 Performance

[Glen Zook]

Of all the Collins A-Line receivers, the 75A-1 gets the best reviews for AM followed by the 75A-2.  Those receivers are not mentioned in the article.   The RX-1 Mohawk definitely has its problems on AM.  One thing about the Mohawk is the 3rd gain control (instead of 2 gain controls on most receivers), namely the i.f. gain control.  Using that i.f. gain control gets some "getting used to"!  The audio from the Mohawk is generally bassy.  Sometimes, I think that Heath made the audio in the TX-1 Apache higher pitched so that when it was received by a Mohawk it sounded better!

The 75A-4, as well as the 75S- series of receivers and the 51S- series, were designed for SSB and definitely do not have excellent AM audio.  The Collins 51J- series, the R-388-series, and the R-390-series do have better sounding AM.  Those are mentioned as being among the best receivers for AM.

A receiver with excellent AM "sound" is the RME-6900 which also has, at least among the receivers that I own, the best received audio for SSB.  I honestly believe that this is due to the fact that, at the time, RME was owned by Electro-Voice and was manufactured in the same Buchanan, Michigan, plant as the high end speakers and microphones.

I own, have owned, or at least have worked on, almost all of the receivers mentioned in the article.  There are exceptions, but, I do agree with a lot of the comments.  If one wants some really good sounding audio, some of the "olde tyme" TRF receivers can have excellent AM audio.  Of course, they are "broad as a barn" in terms of bandwidth.

Some, but definitely not all, of the receivers I own are pictured at

http://k9sth.com/uploads/Equipment_at_K9STH-9_January_2013.pdf

 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: Eddy Swynar <deswynar at xplornet.ca>
To: Glen Zook <gzook at yahoo.com> 
Cc: jack m <oldvette at hotmail.com>; "heathkit at mailman.qth.net" <heathkit at mailman.qth.net>; "yash at aol.com" <yash at aol.com> 
Sent: Monday, February 18, 2013 3:12 PM
Subject: Re: [Heathkit] SB-301 Performance
 



Hi Glenn,

Well, it came to AM reception, at least, this reviewer did NOTgive any of the Collinsreceivers much credit, to whit:


Ten Worst Receivers for AM Use
 
	1. Heathkit Mohawk.  A passel of design mistakes make this very attractive receiver almost worthless for ham use.  Heathkit took advantage of every opportunity to add distortion they could.  Electric Radio had a 3-part article several years ago that outlined the steps necessary to correct these deficiencies.  If you have the patience and expertise to do the mods, this radio has definite potential.
	2. Hallicrafters S-38 and S-120.  5-tube radio little better than an All-American 5 clock radio.  Cute to put on the shelf but worthless for ham use.  There are many other receivers in this class including many Heathkits, Nationals, etc.
	3. Hammarlund HQ-170/180.  My personal prejudices at work here; many guys love theirs.  Incredibly distorted audio with a real JS audio feedback network.  Ugly.  The BFO and notch filter coils prone to breakage.  Chassis prone to corrosion.  It is a pretty decent battle-mode receiver with selectable sideband and an effective notch filter.
	4. Collins 75A-4.  The most over-rated receiver ever.  A pretty decent radio for SSB, the audio is restricted and distorted.   Front end design not commensurate with Collins reputation for high performance.  The huge number of modifications out there are testimony to the weaknesses of the stock radio.  Extraordinarily expensive for what you get.
	5. Collins 51S-1.  Another over-rated receiver.  Matches the Collins “S” line.  Again, this radio is pretty decent for SSB if you don’t connect it to an effective antenna.  Otherwise you’ll find Deutche Welle and Radio Havana all over the place.  Very poor front-end performance.
	6. Icom R-71A.  Noisy synthesizer, not very reliable and difficult to fix. 
	7. Hammarlund HQ-100/105/110.  Poor performance coupled with awful audio.  Small and cute; decent backup receivers, but don’t buy one for the primary station receiver.
	8. Hallicrafters S-85, SX-99, SX-110, S-105.  All pretty much the same radio in different cabinets and slightly different features.  Not truly awful but frustrating to chase a signal around due to the drift.
	9. Hallicrafters S-20R “Champion of the Sky”.  Sounds better listening on an outside speaker – like a PA horn.
	10. Realistic DX-300/DX-302.  Synthesized receivers that seemingly have potential, but lack any sensitivity whatsoever.  Noisy and prone to overload.  Their only saving grace is they’re cheap.