[ARC5] Starting on a RAL clone

[Geoff]

Junker RBL's are cheap as it is usually the outside that is bad. Just 
repackage it. National and W-G built thousands. Coverage goes only to 600 
kc.

OTOH I believe he wants a RAL for HF and I often see them for $50-75 pickup 
only. Time to find one and some hams willing to do a relay on their travels; 
might take a year (-;

Carl


----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: <wrcromwell at gmail.com>
Cc: <Arc5 at mailman.qth.net>
Sent: Wednesday, March 20, 2013 1:41 PM
Subject: Re: [ARC5] Starting on a RAL clone


> On 20 Mar 2013 at 12:32, Bill Cromwell wrote:
>
>> I will be using miniature tubes. Think 6BA6 or something like that. I
>> have them by the dozens. To help with the decision about which tubes to
>> use I'll compare their characteristics to the 6D6 and 41 tubes used in
>> the RAL.
>
> Bill: the 6D6 is the same as the 6K7, which is a double-ended 6SK7. The 41 
> is the same as
> the 6K6.
>
> You might wish to look closely at the schematic diagram for National's 
> RBL. It appears to me
> to be a somewhat updated (uses later tubes) and simplified version of the 
> RAK.
>
> The two RF amps in the RAL are used, primarily, to prevent detector 
> radiation from reaching
> the antenna, and to isolate the detector from antenna effects...although 
> the RF tuned circuits
> also provide considerable RF selectivity.
>
> The gain of the two RF amps is purposely kept fairly low.
>
> Remember that the detector stage 1) operates at fairly low voltage, and 2) 
> that the most
> critical voltages at the detector are all regulated.
>
> The RBL really should have been designed to include regulated voltages to 
> the detector: it
> drifts noticeably.
>
> Also, all the coils in the RAL (and the RAK) are toroidal, wound with Litz 
> wire. They are very
> high "Q", and unusually low resistance.
>
> I MAY have a junker RAL here out of which I could grab the coils and the 
> tuning mechanism
> for you if you want them. They would certainly be cheaper to ship than an 
> entire receiver.
>
> It will take some time for me to find anything useful though...
>
> Ken W7EKB
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