[Boatanchors] Wanted

[Richard Knoppow]

----- Original Message ----- 
From: "GARY BROWN" <XFRMRS at ROADRUNNER.COM>
To: <boatanchors at mailman.qth.net>
Sent: Sunday, April 13, 2014 5:03 AM
Subject: [Boatanchors] Wanted


> Looking for a manual for the RCA, CR-88A. The BAMA site 
> has one for the CR-88 and the schematic is way to small 
> for my eyes.
> Regards,
> Gary

     There may be a link from the Western Historic Radio 
Museum site  http://www.radioblvd.com/index.html
     There is more information including a chart showing the 
various versions at:
http://www.qsl.net/w2vtm/AR88_Information_Page.html

   This site also has a very extensive section on the AR-88 
series.
   The schematic and general details of the CR-88 are 
identical to the AR-88, the main difference is that a 
control for the crystal filter phasing capacitor is brought 
out the front panel. There are no details about the 
mechanical changes anywhere that I've been able to find. 
There were some later versions of the CR-88 with a mask for 
the main dial and some other changes but these receivers are 
extremely rare.
   The CR-88A is modified for use in the RCA triple 
diversity receiver DR-89, it is virtually identical to the 
AR-88F except for the phasing control as mentioned above.
   Also see:
http://www.radiomuseum.org/m/rca_usa_en_1.html

And;
http://www.qsl.net/w2vtm/rca_equip.html

    There is also an RCA equipment mailing list at:

http://mailman.qth.net/mailman/listinfo/rca

    Much of the material in its archive concerns the AR-88.

    The AR-88 is a remarkable receiver, well worth the 
effort of restoring. You will need to replace all the paper 
capacitors. Early versions used RCA-made mica caps, these 
are lozenge-shaped and of an odd pinkish purple color. They 
are usually still good. In war-time receivers many of these 
were replaced in production with flat Micamold or Solar 
paper caps, probably because of a shortage of mica. All 
these should be replaced. Also, the oil-filled bypass caps 
often leak oil and must be replaced. I used modern film caps 
mounted on terminal strips. Trying to clean out and restuff 
the old tubs is too messy for me. The silver mica and 
tubular ceramic caps used in the RF section will almost 
always be good and should be left alone. The oil filled 
paper filter caps in my AR-88F are still good.
    The AR-88 was designed with no electrolytic caps and, 
until the CR version nothing except the rare meter and 
headphone jack was mounted directly on the front panel.
    Note that on the diversity sets AR-88F and CR-88A there 
are some mods to the AVC circuit. This is to allow a gain 
trimmer control (mounted on the front) and to reduce the AVC 
delay by introducing a small positive voltage at on the AVC 
buss to reduce the normally negative voltage there from 
about 1.2 volts to about 0.8 volts. This was apparently 
necessary to improve the diversity action. Its easy to 
return the AVC to original although it does not make a big 
difference in performance as a stand-alone receiver.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com