[Collins] 75A-2 new to me

[Al Parker]

Hi Larry,
    A while back I was working on a 75A-2 for a local club member, and
ordered a manual for it from Al Bernard.  I didn't know there was a
difference, but apparently early ones were (or was it the older ones that
were? ;-) )
    Here's what I learned in talking with Al B:

8/10/03
> But, the schematic doesn't agree with his rcvr,  s/n 71.
> His has the following tube differences, maybe more:
> actual   vs  skem
> 6AK5       6CB6  V-1 RF
> 6BE6        6BA7  V-2 1st mix
> 6BE6        6BA7  V-4 2nd mix
>
> Do you have a different schematic avaliable?
 > s/n 71 may be a real early one, yours later.
---his reply -- 
Apparently  a small number of early 75A-2's used the 6AK5
 for V-1 and 6BE6 for V-2 and V-4.  I have that
version in a 75A-2 Sams Photofact  (June 1952)
and could send you that schematic  if you like.
===========
    (his manual was a real beaut., if you get to Orlando this wkend, look
him up)
    So, be aware of the dif. when you go for a skem.
    FWIW I'm now working on an R-388, s/n 495, MFP'd Nov. 52, that uses
the 6AK5's & 6BE6's in the RF secn, similar to the early -A2's.
    There was an article in an old CQ mag for a prod. det. built on a
turret plug that'd plug into the NB socket, fairly non-invasive.  I've got
the article & a turret, one of these days when I get a round tuit I'll do
the deed.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info

==============
Message: 5
Date: Mon, 07 Feb 2005 21:59:31 -0700
From: telegrapher at att.net
Subject: [Collins] 75A-2 new to me
To: COllins at mailman.qth.net
Message-ID: <42084733.71755017 at att.net>
Content-Type: text/plain; charset=us-ascii

> Picked one up the other day.  Nice looking and very good calibration.
> "S" meter movement acts like it is in slow agc mode.  Receiver takes
> 300uv to reach S-9.  I've not checked the tubes in the RF section yet
> but had to replace about half the other ones so i'm hoping that will
> cure some it's hearing ills.
>
> There was no schematic diagram in this manual so i'm in the dark with
> it.  Someone or several folks have been under the radio judging from the
> solder joints.  They've also added the tube and wiring for an NBFM
> adapter.  Serial number is in the 400 range so i'm wondering if this is
> just a low range receiver or did they not make that many of them.
<snip>
Larry
W0OGH