[Collins] 51J4 vs 75A3?

[jrhallas at optonline.net]

I agree that the A4 is a much better ham receiver for everything, unless you just want to do AM, then the A2 or A3 would be fine, although I have had and enjoyed an A2, I haven't had an A3 and can't speak to the problems Jim mentions.

With the A4, in addition to the product detector, you get the first SSB/CW capable AGC system and the first passband tuning system. It is a fine radio, although suffers from much too high a tuning rate unless you get the reduction drive (also true of the others - I have one on my J4, and wouldn't leave home without it!).

Read over the "Vintage Product Review" in Jan 06 QST.

GL & 73, Joel
Joel R. Hallas, W1ZR

----- Original Message -----
From: Jim Brannigan 
Date: Tuesday, February 13, 2007 10:09 am
Subject: Re: [Collins] 51J4 vs 75A3?
To: jeide at execpc.com, Eugene Hertz 
Cc: collins at mailman.qth.net

> The 75A3 is an 75A2 AM radio with a mechanical filter module.
> The mechanical filter modification was not well thought out. 
> The filter and 
> additional IF amplifier upset the gain balance of the radio and 
> introduced a 
> lot of IF noise.
> I tried all manner of mixer changes and product detectors in my 
> 75A3. There 
> was no changing that sows ear into a silk purse.
> 
> The 75A4 and S-line receivers were completely new designs.
> 
> Jim
> 
> 
> >> So I've begun to think about replacing the 51J4 with an 
> amateur band 
> >> receiver such as the 75A3. Why not the A4 you might ask? 
> Well, I really 
> >> prefer the cabinet arrangement and style of the J4/A3 models 
> better. For 
> >> me its strictly an asthetics issue.
> >>
> >> So I was wondering what folks on the list thought of using a 
> 74A3 with a 
> >> product detector mod? I know one main difference (besides the 
> general/ham 
> >> bands) is that the A3 has only 2 mech filters, whereas the J4 
> has 3. I 
> >> should point out that I only own 2 filters for my J4 so in a 
> strict 
> >> comparison, I wouldn't be losing anything on that front.
> 
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