[Amps] Chinese FU-724F

[Carl]

----- Original Message ----- 
From: <gdaught6 at stanford.edu>
To: <amps at contesting.com>
Sent: Wednesday, November 27, 2013 11:53 AM
Subject: Re: [Amps] Chinese FU-724F


> Hsu wrote...
>
>> I found a Chinese cheap triode for industry, filamnet 6V/50A;
>> Pamax=2.5kW; Grid diss=150W;Umax=6kV;
>> u=70, you know most industrial triodes are low/ meidum u tubes, but
>> this one is high u tube.
>> As it is  idustial tube , so the  price is cheap.Any suggestion?does
>> it  fit hamradio well?
>
> Look at the mu (amplification factor) for the 3-500Z, or the 8877, for 
> example:  160
> and 200.  With a mu of 70, it will take considerably more drive power than 
> what is
> usual for amateur service.
>
> 73,
>
> George T Daughters, K6GT
> CU in the California QSO Party (CQP)
> October 4-5, 2014


No argument there but many rigs have excess power to burn and many others 
use an IPA to drive a YC-156 and other tubes with handles anyway. That is 
what the ALS-600, SB-1000, AL-80 family, etc are used for.

Also several of the old glass tetrodes popularly used in GG wind up with an 
effective mu not much above the FU-724F, especially when run at a voltage 
well below their maximum. Think 4-1000A or a 4-400 used in a SB-220.

Carl
KM1H