[Amps] 572B - News?

[Marcelo Cabral]

Hi, Gustavo! 

Thanks for the tip, despite I'm thinking in avoid a big mod for the amp because I'm building my home tower (60 ft), assembling one amplifier running 2 x GU43B, and restoring an old Brazilian made Rig... I'm starting to convince the mod will be the best way. 

73, 
Marcelo - PY1KR.  
 

-----Original Message-----
From: Gustavo V [mailto:lu6avm at gmail.com] 
Sent: sexta-feira, 7 de novembro de 2014 13:06
To: Marcelo Cabral
Subject: Re: [Amps] 572B - News?

Hola Marcelo.

you can modified your amp to use 2x Gi7BT russian tubes, just buy from http://UR4LL.net  Dr Alex is a nice person and sell original SOVIET tubes :)

I'm building one right now and I got several matched tubes (same lote)

your modifications will be really few, your HV PS give you the correct voltage (2400V) that are ok for Gi7Bt, maybe have to modified/change the filament one...




73's
Gustavo
LU6AVM


On Fri, Nov 7, 2014 at 4:31 AM, Marcelo Cabral <py1kr.marcelo at gmail.com> wrote:
> Hi, all!
>
> I'm Marcelo, from Brazil, my call is PY1KR. This is my first message 
> for the group and I like DX and Electronics issues.
>
> I have a small Yaesu 2100Z and last week one of the "Taylor" (RF 
> parts) 572B starts to present a weak blue glow, the Idle current of 
> the amp was increased and this same tube is overheating. I've checked 
> Bias, Cathode HV and LV Anode voltages, all appear to be ok.
>
> Swapping the tubes position, the problem follow the tube pointing the 
> solution for a new one.
>
> Where to find good tubes? Maybe the easy way for get a reliable amp 
> must be swap the glass tubes for ceramic (like GI7B, 3CX)?
>
> This MP of 572 was used no more than one year and no more than 60W 
> driven in good SWR antennas (near 500W in continuous carrier). I'm 
> very disappointed, and thinking because of problems like this RFparts 
> stop to sell these Chinese tubes remarked, recently I've change some 
> mails with Terry from RFparts and he don't appear very cheerful about new tubes...
>
>
> My best regards,
> Marcelo - PY1KR.
>
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