[Premium-Rx] The "Sound" Of Receiver IF Amplifiers

[Carcia, Frank A. HS]

Hi Gary,
I own a TR7 for the same reasons. A friend is working on the audio and has
increased the values
of caps in the audio circuit. Check back in Ham Radio there was a bunch of
mods possible for
that radio. I rebuilt my unit a couple years ago and have no desire to
replace it. fc

-----Original Message-----
From: Gary Follett [mailto:gfbike at iaxs.net]
Sent: Tuesday, October 07, 2003 8:48 AM
To: Llgpt at aol.com
Cc: premium-rx at ml.skirrow.org; Bob Milne
Subject: Re: [Premium-Rx] The "Sound" Of Receiver IF Amplifiers


I too have noticed that many otherwise excellent receivers have really 
annoying received audio quality. The most notable of these (for me) is 
the Drake TR7. Historically one of the very best receivers of its day 
from an RF perspective (at least in Ham Radio circles), the received 
audio has always been harsh. No amount of tweaking could do much to 
improve it, even the use of an outboard audio stage taking off before 
the internal audio amp. I have long suspected that the IF stage was the 
issue, and was considering designing up an outboard receive 
IF/detector/audio processor for that radio when I had it. I owned about 
8 of those over the years because of their RF performance and 
serviceability, NOT for their receive audio quality!

My Signal One 1030, on the other hand, has exceptional receive audio, 
though not as nice as my Plessey, which sounds more like good FM 
reception (even in narrow SSB) than AM or SSB. Likewise, my Sunair 
RT9000 delivers superb audio on SSB, with an almost bizarre response to 
noise such as static crashes (a rather pleasant response, but bizarre 
nonetheless - I don't really know how to describe it as it is like no 
other receiver I have heard.)  Its sonic performance on AM leaves a lot 
to be desired, but it was never intended much for AM reception. Since 
it is so stable, however, it does a respectable job in receiving AM in 
the SSB mode, though it performs best with an outside speaker because 
the receiver is somewhat microphonic. (All 5 of the ones I have had 
show this same issue so it's a design issue, not a problem with one 
particular set) Again, this radio was never intended much for AM use so 
it's not an issue for this set.

The most pleasant receiver I have ever listened to is the Rockwell 
Collins HF 2050. Some would disagree but I had the chance to use it in 
some very harsh conditions and it's so pleasant to listen to that I 
could use it for days on end without annoyance. Despite its many 
quirks, it excels in this respect over all others (IMHO). Not true for 
any Ham quality receiver I have ever heard (except the Signal One, 
which was prohibitive in cost for most Hams).

That's my 2 cents...

Gary


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