[Boatanchors] NC-240D question

[Rodger]

Carl,

I don't know if National did this (and you probably have the best 
information of all of us on the list concerning National!) but I know 
that Bill Orr wrote an article about this receiver and suggested that 
tube change.  I will go through my HR collection (I have them on DVD) 
and see if he mentioned any National connection for the inspiration for 
that modification.  I have a couple of 240D's along with an NC-100, 
101X, and RAO-7 (similar to an NC-100XA) so it is obvious I like the 
sliding coil Nationals!  They are among my favorite receivers.  I also 
have a Pierson KP-81 with a sliding coil catacomb and I am sure there is 
quite a bit of National/James Millen inspiration in that receiver.

73, Rodger WQ9E

P.S.  Did you have any experience with the NC-400 while with National?  
I have one and it has a lot of things to like about it but the frequency 
stability is terrible (jumping-not drift) from about 14 megahertz up.  I 
have corresponded with 2 other 400 owners and they have the same 
experience.  I wondered since it comes stock with external HFO inputs if 
the design intent was mostly to use an external oscillator?  On the low 
bands it is a great receiver with very nice selectivity.

jeremy-ca wrote:
> I decided to start to work today on a recently acquired NC-240D. The 
> first thing that I noticed is that the mixer tube was missing a grid 
> cap and it turned out that a 6SB7Y was installed.
> I removed the bottom cover and after removing the mouse nest over the 
> xfmr area and moving the rack over I noticed that the rcvr had been 
> recapped at some time in the past. It had the same Sprague caps that 
> National used in the Service Dept in the 60's for overhaul of the 
> oldies and the same neatness that the Svc Dept was known for.
>
> The 6SB7Y conversion also looked factory neat and you would swear it 
> was original. The question is: does anyone know of that conversion 
> and/or know if National might have done it? I was in the Svc Dept 
> 1964-67 but dont remember anyone mentioning that swap. However lots of 
> strange things went on back then, especially with the HRO-50 & 60 so 
> nothing would surprise me.
>
> The 6SB7Y has almost 3X the transconductance of the 6K8 and the late 
> 50's sunspot peak probably prompted someone to hop the old girl up on 
> 10M.
>
> Carl
> KM1H
> National Radio 1963-69
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