[Heathkit] SB-301 Performance

[Eddy Swynar]

On 2013-02-18, at 3:53 PM, Glen Zook wrote:

> The 400 Hz filter in the SB-301 is fine for most CW operation.  However, the 200 Hz filter that came in every 75S-3 and 75S-3A from the factory is better when one has to really "dig" a signal out of heavy QRM (every 75S-3 and 75S-3A was shipped with the 200 Hz filter which, unfortunately, was a high cost accessory in the 75S-3B and 75S-3C).    The selectivity of the 400 Hz Heath filter is about the same as the Collins 500 Hz mechanical filter in one of my 75S-1 receivers.  But, overall, I definitely think the SB-301 is a better receiver than either the 75S-1 or 75S-2.
> 
> The variable BFO in the 75S-3, 75S-3A, 75S-3B, and 75S-3C is better than the fixed BFO in the 75S-1, 75S-2, SB-300, and SB-301 especially in the fact that one can vary the received tone frequency of the CW signal.  With the crystal controlled BFO, the tone frequency is pretty high with the CW filter which, at least for me, is uncomfortable.  The 500 Hz CW filter in the 75S-1 and 75S-2 are normally used with a 3rd BFO crystal which definitely lowers the tone frequency.  I did add one of these 3rd BFO crystals to my 75S-3A to lower the tone when the 200 Hz filter is used so that I don't have to always use the variable BFO.
> 
> I also have one of the Eldico R-104 receivers (along with the T-102 transmitter and control console) which was the 2nd source military receiver for the Collins 75S-2.  The order of ranking, from lowest to highest, at least in my opinion, of these receivers is:
> 
> Collins 75S-1, Eldico R-104, Collins 75S-2, Heath SB-300, Heath SB-301, Collins 75S-3B, Collins 75S-3C, Collins 75S-3, and Collins 75S-3A.  All of the Collins 75S-3- series receivers are pretty close.  However, the 75S-3 and 75S-3A were manufactured before the "bean counters" got involved with production costs and they do have a very slight edge in performance.  Of course, the only difference between the 75S-3 and 75S-3A is the additional crystal deck.  There is one change made in the later 75S-3B and 75S-3C receivers that can be made to the 75S-1, 75S-2, 75S-3, and 75S-3A receivers which definitely makes an improvement.  That is to move one of the 455 kHz i.f. cans from the AM filter to the 2nd mixer output.  This widens the AM bandwidth and makes a definite improvement to the 2nd mixer.
>  


Hi Glenn,

Well, it came to AM reception, at least, this reviewer did NOT give any of the Collins receivers much credit, to whit:


Ten Worst Receivers for AM Use
 
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.
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.
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.
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.
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.
Icom R-71A.  Noisy synthesizer, not very reliable and difficult to fix. 
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.
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.
Hallicrafters S-20R “Champion of the Sky”.  Sounds better listening on an outside speaker – like a PA horn.
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.
 
 

You can see the whole write-up by clicking onto: http://amfone.net/ECSound/JNRECS.html

...And no, the SB-301 goes completely unmentioned therein...!   :o)

~73~ de Eddy VE3CUI - VE3XZ