[Amps] amp cooling / triodes vs tetrodes

[Carl]

Many use a foot switch

Carl
KM1H


----- Original Message ----- 
From: "Peter Voelpel" <df3kv at t-online.de>
To: <amps at contesting.com>
Sent: Tuesday, April 03, 2012 10:31 PM
Subject: Re: [Amps] amp cooling / triodes vs tetrodes


> Why should one care about an amplifier without EBS or high idle current at
> all?
> That current is only drawn if actually transmitting and not in standby 
> mode
> without output power.
>
> 73
> Peter, DJ7WW
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Jim Thomson
> Sent: Dienstag, 3. April 2012 17:46
> To: amps at contesting.com
> Subject: [Amps] amp cooling / triodes vs tetrodes
>
> Date: Mon, 02 Apr 2012 12:59:10 -0700
> From: Jim Barber <audioguy at q.com>
> Subject: Re: [Amps] amp cooling / triodes vs tetrodes
> Leigh,
>
> Not to drive everyone up a tree with this topic, but do you know of any
> non-proprietary designs that might serve at least as a basis for a
> properly-done EBS implementation?
>
> I'm not thinking so much of modifying my (newest) commercial amp, but I
> do have a YC156 project that seems to be in eternal overhaul, as well as
> a Henry 3KA that could benefit from such a beast.
>
> Along that line I also (still) have one Alpha 77 left with their EBS,
> but I'm not sure I'd qualify that one as more than a good start at
> "properly done", at least by today's standards. (It's from before they
> added the control pot, early design)
>
> Thanks,
> Jim N7CXI
>
> ### You can buy the entire TRI-state EBS  from the Ameriton catalog.
> They have 1-2 versions  of it.  Complete, ready to go.
> It might need  some tweaking to obtain higher V levels for  a YC-156.
>
> ## I dunno why you would want to mess with EBS....if you use VOX  on SSB.
> You don't need to suck 350 ma of idle current on a YC-156. 150-200ma is
> plenty.
> 150 ma idle on a 3CX-3000A7 triode is plenty for  superb imd .
> 150-200 ma idle on a 3CX-6000A7 is ample for good imd.
>
> ##  On CW mode, there is NO reason at all to suck
> 150-350 ma of idle current !!!!     On CW, just crank up the bias V..until
> the
> idle current is down to 10-20ma.    Use a  string of series 1N5408 or 6A10
> diodes
> for this job..  and or...  a  single wire wound resistor.   On CW..with 
> any
> GG triode
> you can not run the idle current at zero ma...or you will get key clix.
> With 10-20ma
> you wont get any at all.  Tank eff will be improved a whole bunch too. 
> Your
> idle power
> will be  so low, it's a non issue.
>
> ##  EBS, even tri-state is a fubar way to go on CW..and also FM.
>
> ##  EBS, if using PTT SSB  is ok..and saves heat.    If using VOX  on ssb,
> the  ebs  will
> not buy you much for heat savings at all.   The only time it kills heat is
> between when you
> stop talking..and when the VOX drops out.   The EBS is NOT gonna be fast
> enough to  toggle
> between syllables !
>
> ##  If you want to see something really stupid, check out the 3 x hole
> tetrodes   from  QRO, etc.
> They idle at a whopping 750ma !     The 2 x holer idles at 450 ma  (225 ma
> per tube)
> Using the 3 holer with the same plate xfmr as the 2 holer is even more
> silly.   If any
> sb-220 etc, sucked 750ma, it would burst into flames.
>
> ##  sure the small tetrodes can be driven with 10-20 watts.   Who cares.
> The typ xcvr puts out
> 100-250w these days.   You run a 200w xcvr at just 20 watts out..and the 
> eff
> goes straight to hell,
> and ditto  with the TX imd.   You really require a good 3-9db pad to run
> those low power  tetrodes
> properly..when  driven from your typ xcvr.
>
> Later........ Jim  VE7RF
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1424 / Virus Database: 2113/4913 - Release Date: 04/03/12
>