W3LPL amplifiers

ERIC.L.SCACE at adn.sprint.com ERIC.L.SCACE at adn.sprint.com
Thu Jul 14 20:26:04 EDT 1994

   The following is first-hand experience.  The situation described has been
the case at W3LPL since the late 1970s, when I first started operating there
(as a single op on phone!).

   W3LPL has six single-band homebrew amplifiers.  Each contains a single
3-1000Z tube, run grounded grid.  The amps are fed from a single HV power
supply.  Each amp chassis has its own filament supply.  Pi-L networks are used
in the output stage to keep cross-band interference down.  Each amplifier is
monitored by built in grid- and plate-current meters, and an independent Drake

   The HV supply contains a variac, a holdover from the old regulations when
PEP limits for SSB were different from the power limit for CW.  The HV supply
is adjusted so that the tubes put out 1500W with grid- and plate-currents
within the tube design limits.  While the amps sit in front of each operating
position, the HV supply is in the bottom of an equipment rack, behind a bunch
of operating tables and surrounded by a snake-pit of coax and control cables. 
No one ever bothers going back there; there's nothing to see and nothing to

   While it might be possible to crank up the transceivers to 200W output and
drive the tubes a littler harder to get the wattmeter to say 1600 or 1700W,
the other operators complain immediately because of the IMD crud that starts
to show up.  (Remember that there are two radios listening on each band.  The
spotting/multiplier operator is trying to listen when the running station is
sending -- so the slightest amount of trash (including phase noise from TS-940
transmitters) really mucks up the bands.)

   This arrangement is a set-and-forget system for a multi-multi station.

   I don't see this qualifying for the "gas" category of station - hi!

>From Randy A Thompson <K5ZD at world.std.com>  Fri Jul 15 03:45:34 1994
From: Randy A Thompson <K5ZD at world.std.com> (Randy A Thompson)
Date: Thu, 14 Jul 1994 22:45:34 -0400 (EDT)
Subject: was: IARU Score - 9V1ARU (now W5WMU power)
Message-ID: <Pine.3.89.9407142241.A16133-0100000 at world.std.com>

On Wed, 13 Jul 1994, Dave Pascoe wrote:
> Tom, we believe you and I'm sure many of us could tell similar stories.  
> But the many reports of extremely loud backscatter signals really tell 
> the story.  I've heard W5WMU on direct and scatter paths and I'm fairly 
> confident that he runs in excess of 1500W PEP.  Maybe we're all wrong, 
> but I'll go out on the limb.  We're not that stupid.  But, to each his 
> own.
> -Dave KM3T
>  km3t at mathworks.com
I have noticed that KM3T has had some succes in contesting from a few 
locations.  He usually does really well in contests that require working 
Europeans.  Since he works so many, I am just really, really sure that he 
must be running high power.

How else could he work so many?

In the recent VHF contest, Dave was doing 6m.  Even though he missed 
several hours, he still had one of the best scores in the contest.  How 
could he get this advantage on VHF?  Maybe he broke a bunch of calls and 
got some extra QSOs that way.  Yeah, that must be it.

I have always wondered about Dave.  Is he a good operator, just lucky or 
something else...?

Sorry to throw stones at your glass house Dave.  I don't believe any of 
the above allegations are true.  But by making my speculation publicly, I 
am not doing anything different than your classless allegations against 

My experience is that W1's can't understand why anyone would run high 
power (after all, they don't need it).  My experience is also that most 
ops, even the I-never-run-power ones, will do it if they can.  Much of 
their "religous zeal" against power is only because they don't have it 
available for themselves.

Randy, K5ZD
k5zd at world.std.com

More information about the CQ-Contest mailing list