[ARC5] Opinions on ARR-7

[Richard Knoppow]

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "J. Forster" <jfor at quikus.com>
Cc: <Arc5 at mailman.qth.net>
Sent: Sunday, August 26, 2012 2:38 PM
Subject: Re: [ARC5] Opinions on ARR-7


> On 26 Aug 2012 at 12:10, J. Forster wrote:
>
>> What do people think of the ARR-7 as a receiver? To me, 
>> it seems far more
>> ELINT than communications.
>
> First of all, it is a "repackaged", SX-28A, with 
> significant enhancments, including being much
> easier to work on, more stable, and more sensitive on the 
> upper bands..
>
> Secondly, it is supposedly an excellent receiver.
>
> I've always wanted one...but then again, I have a "thing" 
> about receivers.
>
> There is one for sale right now on eBay for very little 
> money. They guy who has it for sale
> doesn't know what it is.
>
> Also, there was recently an article in Electric Radio 
> Magazine on that receiver.
>
> Ken W7EKB

     It seems to borrow heavily from the original SX-28 but 
to me the circuits more resemble the SX-32.  The SX-32 seems 
to be a forgotten model. It was essentially an SX-28 without 
the Lamb noise blanker.  Evidently the Lamb blanker did not 
work well in practice because there is a service bulletin 
for replacing it with a series diode limiter.  Both the 
SX-28A and SX-32 used 6AB7 as first RF. The SX-32 has 
connections for diversity.
     The first tube in the ARR-7 is not really an RF 
amplifier but appears to be an untuned RF stage to isolate 
the antenna from feed through of the LO. It may be that it 
set the noise level of the receiver.


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