[MAMS] [Mw] tubes for the 6155 one more comment

Tue Jan 1 10:49:32 EST 2013

RF Parts indicates that they sell Svetlana tubes but I found sealed packages on e-bay single tube $100.00 or pair $200.00. They come from the Ukraine. When I bought mine they went first sent to an expeditor  in Texas but I'm pretty sure I didn't get them off e-bay. mark, K8MD

--- On Mon, 12/31/12, John T Rose <ww1z_1 at juno.com> wrote:

From: John T Rose <ww1z_1 at juno.com>
Subject: Re: [MAMS] [Mw] tubes for the 6155 Re:Back On 222mhz with Amp
To: aa9il at sbcglobal.net
Cc: mams at mailman.qth.net, microwave at lists.valinet.com
Date: Monday, December 31, 2012, 10:00 PM

I believe it was some one in the midwest who had machined adapters to put
use a 4CX250 tube.  But that was a long time ago.  The 4CX400/GS36B works
nicely in these amps, but don't know if they are still available.  You do
have to carefully bend the anode fingers as the 4CX400 tube anodes are
about 50 mils smaller.  They will put out significantly more power and
are potentially cleaner.  The Amperex DX-393 is another tube that these
amps could use.  I have used all three of these tubes.  One thing to
watch is the regulated screen current range is not that wide.  So
depending on the tube and how it is tuned the tube can try to draw more
screen current then the supply is capable of.  I.E. OK tuned with a
carrier, but tries to draw too much current with a SSB signal.   As I
recall these were built to run 50 watts carrier output AM.  In the early
60's an Eimac engineer wrote an excellent article on screen current in
tetrode amplifiers in QST.  Don't remember the issue.  Really good
reading if you have not tuned a tetrode amplifier.

73 John, WW1Z

On Mon, 31 Dec 2012 10:06:39 -0800 (PST) aa9il at sbcglobal.net writes:
> Hello All
> While on the topic off the 6155, is there a source for the 8930?
> I have heard that a 4CX250 will work provided there is something
> to shim it in the socket.  A long time ago, I heard of a machined
> adapter for the tube.  I have an amp Im going to put
> on 2m that has the original tube and I would like to get a spare
> or go the 4cx250 route if need be.
> 73 de Mike
> AA9IL
> 
> 
> --- On Mon, 12/31/12, MARK K8MD <k8md at sbcglobal.net> wrote:
> 
> > From: MARK K8MD <k8md at sbcglobal.net>
> > Subject: Re: [MAMS] Back On 222mhz with Amp
> > To: "Mid-America Microwave Society" <mams at mailman.qth.net>
> > Date: Monday, December 31, 2012, 11:52 AM
> > Dave I bought one fan from Fair Radio
> > and I'm not sure if it will work, If you make the pass thru
> > here for June contest(I don't think you rover January
> > contest) I'll show you the fan.
> > 
> > --- On Mon, 12/31/12, David DeVos <kf8ql at yahoo.com>
> > wrote:
> > 
> > From: David DeVos <kf8ql at yahoo.com>
> > Subject: Re: [MAMS] Back On 222mhz with Amp
> > To: "Mid-America Microwave Society" <mams at mailman.qth.net>
> > Date: Monday, December 31, 2012, 11:26 AM
> > 
> > Glad to hear you got it fixed Mark.  I'd love to get a new
> > fan, but I went to 
> > the Fair Radio site and did not see them listed.  I did buy
> > a new set of bearing 
> > for the fan from a Canadian fellow on the web, and I will
> > swap those out and see 
> > if that quiets my 2m amp blower.  
> > 
> > 
> > Happy New Year from KF8QL in EN72fu!
> >  Dave
> > http://www.davedevos.com 
> > 
> > 
> > 
> > ----- Original Message ----
> > From: MARK K8MD <k8md at sbcglobal.net>
> > To: mams at mailman.qth.net;
> > mw <microwave at lists.valinet.com>
> > Sent: Sun, December 30, 2012 5:39:17 PM
> > Subject: [MAMS] Back On 222mhz with Amp
> > 
> > I purchased an AM 6155 to fix my AMP. It was not modified so
> > for last couple 
> > days I exchanged modules and proceeded to do Modes to
> > Different sections and 
> > exchanged them with what I had. Took 8930 that came with
> > purchased amp and I'm 
> > seeing 450W most I've seen on band. I'm also operating off
> > of 220VAC which why I 
> > wrecked the AMP. 
> > 
> > 
> > I purchased a Bias module and fan from Fair Radio but they
> > don't look the same. 
> > I'm thinking that a newer bias circuit was made and
> > manufacture added a small 
> > board on top of the one I modified. The blower had a board
> > attached to it close 
> > to the square cage blower. I didn't use them but they maybe
> > good for parts. 73 , 
> > See in contest Mark, K8MD  
> > 
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