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Re: [Amps] 572B - News?

To: "Marcelo Cabral" <py1kr.marcelo@gmail.com>, <amps@contesting.com>
Subject: Re: [Amps] 572B - News?
From: "Carl" <km1h@jeremy.qozzy.com>
Date: Fri, 7 Nov 2014 11:51:52 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
RF Parts will be taking new 572B orders in Jan 2015, Id rather wait than hack up a perfectly good amp for an inferior tube.
http://www.rfparts.com/tubes/tubes-572b.html

Carl
KM1H



----- Original Message ----- From: "Marcelo Cabral" <py1kr.marcelo@gmail.com>
To: <amps@contesting.com>
Sent: Friday, November 07, 2014 10:46 AM
Subject: Re: [Amps] 572B - News?


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@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@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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