[Boatanchors] National Rx.

[Richard Knoppow]

----- Original Message ----- 
From: "Al Klase" <al at ar88.net>
To: <boatanchors at mailman.qth.net>
Sent: Wednesday, June 29, 2011 3:22 PM
Subject: Re: [Boatanchors] National Rx.


> Larry,
>
> That's clearly an National HRO (Senior).  Note the sockets 
> for "big-pin"
> tubes and the presence of the crystal filter on the right 
> side.  The
> real cognoscenti could tell you more from the style of the 
> IF cans, etc.
>
> Al

    I replied to the original sender and meant to copy the 
list. National changed from glass to metal tubes around 1936 
or 37. The advertising in the 1936 ARRL handbook shows glass 
tubes but remember that the handbook is set up the year 
before. I would have to look through a bunch of old QSTs to 
find the date of the change to metal tubes. I also don't 
know the date of the change of the IF transformers from air 
to ferrite core. National made a lot of changes, some of 
them small, over the production life of the "original" HRO 
from the first to the 5Ta1. All shared essentially the same 
circuit although there were some changes and National 
offered to modify existing receivers at the factory.
    Its hard to tell just how much of this receiver is 
missing, its possible it could be restored but it would 
require replacing the meter, finding plug in coils, etc. I 
agree with Gary Pewitt that it looks like a restoral job 
that got inerrupted. Perhaps the seller has the missing 
parts sitting around somewhere (wishful thinking but you 
never know).


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