R: [amsat-bb] Who has nuvistor experience ?

["i8cvs" <domenico.i8cvs@xxxxxx>]

Hi William, PE1RAH

Early 1963 the well know italian manufacturer John Geloso produced
four model of downconverters for the amateur bands 50 MHz, 144 MHz,
220 MHz and 432 MHz using  the same type of nuvistor 6CW4 for front
end, mixer and xtal local oscillator.

The 6CW4 is a triode with 6.3 volts for filament and 70 volts for the
plate voltage and is very small only 2 cm high including the pins and
2 cm in diameter but since the envelope is metallic it became very hot
during operation and you cannot touch it with your finger !

Also the type 6DS4 was available but it was less popular because more
expensive.

The publisched noise figure from  the manual of John Geloso
downconverters with 6CW4 in my hand are the following:

50 MHz      NF= 3.6   dB
144 MHz    NF= 3.6   dB
220 MHz    NF= 4.77 dB
432 MHz    NF= 6.00 dB

The above downconverters where professionally built but the Nuvistor is
now history and no way to improve the above Noise Figure.

I have succesfully used the above downconverters for 144 and 432 MHz
and I have the technical manuals of it with complete schematic diagrams
and if you are interested I can send it to you as a scanned copy.

Also I have few 6CW4 for spare but I believe that actually the most
difficult part to find as new is the socket for a  Nuvistor.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: William Leijenaar <pe1rah@hotmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, September 20, 2004 9:49 PM
Subject: [amsat-bb] Who has nuvistor experience ?


> Hi AMSATs,
>
> Someone has experience with nuvistors on UHF ?
>
> I know they are more noisy then todays semiconductors, I only want to know
> how I get them as close a possible to todays semiconductor noise levels
:o)
> or when possible equal or better :o)
>
> 73 de PE1RAH, William
> ---
>
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