[ARC5] Stupid Question No.5036
Geoff
geoffrey at jeremy.mv.com
Thu Jul 24 15:46:08 EDT 2014
Your only source of data, without going thru a decade of SAMS folders, is
too look at the transconductance, application, and to realize that tubes are
released with the first alpha character going alphabetical.
This puts the 6GM6 in the lead as the hottest of the 7 pin miniatures. The
6EW6 is not even a contender in most receivers since it is sharp cutoff and
would pretty much disable AGC performance.
Changing the 1st converter to a 6BY6 will reduce tubenoise some more. You
can try a 6BY6 in the 2nd converter and a 6BZ6 in the 1st IF; Ive no real
experience with hot rodding that radio.
I did get about 2X sensitivity improvement on 10M in a NC-300 by changing
the 6BZ6 for a 6GM6 many, many times. OTOH that was just going from hot to
hotter since at bone stock the AM Broad IF position was .4uV for a 10dB SNR.
On 6M and using a dog such as the 6BE6 as a converter there should be a
fairly decent improvement.
The 6GM6 and 6BY6 have been my favorite swaps since the 60's.
Carl
----- Original Message -----
From: "Robert Eleazer" <releazer at earthlink.net>
To: <arc5 at mailman.qth.net>
Sent: Thursday, July 24, 2014 2:00 PM
Subject: [ARC5] Stupid Question No.5036
>I have a stupid question.
>
> Where in the usual tube data is the frequency response for the tube?
>
> I am considering replacing the 6BZ6 RF amp tube on a National NC-270 with
> a tube that will give better performance on 6 Meters. The 6GM6/6EW6 looks
> like a possibility but how do I know that the performance on 6 Meters will
> be better? It is a tube used in the IF's of TV sets, and that sounds
> good, but I see no data that tells what the frequency capabilities of
> tubes are. The old ARRL handbook had the max usable frequency for triode
> transmitting tubes but I do not see similar data for other tubes anywhere.
>
> Thanks,
>
> Wayne
> WB5WSV
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