[Hallicrafters] [National] Nuvista-plug

[Carl]

Good info Les and thanks for doing it.

See my HRO-60 writeup on the 
http://groups.yahoo.com/group/glowbugradio/?yguid=347629384 forum as it 
goes into the necessity of alignment plus a 6GM6 upgrade for the 6BA6 
1st RF.

Ill continue posting there as I go thru various brands and models as 
completely stock or with minor mods.

The offer still stands if you decide to part with the Nuvistaplug. Id 
like to put it thru a few lab tests.

Carl
KM1H


----- Original Message ----- 
From: <lrlayton at cox.net>
To: <Hallicrafters at mailman.qth.net>
Cc: <national at mailman.qth.net>
Sent: Tuesday, April 28, 2009 2:06 PM
Subject: [National] Nuvista-plug


>
> The Nuvista-plug  has been tried in a couple of my radios, just a seat 
> of the pants evaluation but here are the results.
>
> First I tried it in my SX-42 as a sub for the 6AG5 in the first RF 
> stage with poor results... gain was very low and no apparent 
> improvement in noise figure.  Really not usable on any of the bands 
> that use the first RF stage. I did not try to peak up the alignment.
>
> Next, I installed the Nuvista-plug in a National NC-183D that normally 
> uses a 6BA6 in the first RF stage. The results were excellent... lower 
> noise on the higher bands and gain approximately the same. Again, no 
> alignment was done other than  peaking the antenna tune control. There 
> isn't much to hear lately on 6 or 10 meters, but on 27 mHz, it was 
> possible to copy weak local  signals  better than before.  No overload 
> from strong signals was noticed or other ill effects on any of the 
> lower bands.
>
> Les
>
>
> For those who missed the original discussion a couple of weeks ago 
> here is the link provided by Carl to the info on the nuvista-plug (a 
> cascode circuit using two 6DS4 nuvistors designed as a low noise 
> plug-in replacement for the first RF stage in the SP-600).
>
> http://www.mines.uidaho.edu/~glowbugs/SP600upgrd.pdf
>
>
>
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