[Yaesu] re 572B's in FL-2100

Tue, 15 Jan 2002 12:29:08 -0600

 Ive owned a FL-2000 since the 1970`s I may have put tubes in it once but I added one of these electronic bias circuits and never had trouble with the tubes again. It is a very worthwhile addition to any amp. It reduces the tubes dissapation to zero except when you speak. There is a reference at the ARRL site to this article in qst I used a Ham Radio Mag. article from probably the same time period. 
May 1974 QST  36  Electronic Bias Switching for RF Power Amplifiers  Bryant, J.A., W4UX 
73`s and good luck Morris WA4MIT

--

On Tue, 15 Jan 2002 08:16:44  
 Stephen Goldberg wrote:
>According to RF Parts, because of higher amplification factor, the Svetlana
>tubes can go into self oscillation during stand-by because of low cut off
>bias.  They sell a kit ($4.50 US in my old catalog) to change the bias
>supply to a voltage doubler to cure the problem.  I have Cetrons in my
>SB-200 which have performed well and given no trouble.
>
>Steve W4IMF
>
>----- Original Message -----
>From: "Fern Rivard" <[email protected]>
>To: <[email protected]>
>Sent: Monday, January 14, 2002 7:50 PM
>Subject: [Yaesu] re 572B's in FL-2100
>
>
>>     Could some please enlighten me as to the best tubes to use as
>> replacements in Yaesu FL-2100B amplifier.  I see that RF Parts carries at
>> least three different brands. It looks like the Taylor replacements are
>the
>> best buy but there is a warning that using the Svetlana brand would
>require
>> a modification to the FL-2100 amp. What is this mod that they are talking
>> about?
>>     Another supplier only carries the National brand which I have never
>> heard of before but they are made in China. My guess is that those tubes
>> can't be used in the horizontal position.
>>     Any comments or suggestions would be greatfully appreciated.  73's
>from
>> Fern
>>
>>
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