[Amps] Henry 3K-A 'gotchas'?

[Dave Harmon]

My 3K-A has been running steadily since I picked it up new at the factory in
L.A. in 78'.
In 80' I installed a Jennings vacuum relay and an Agastat timer to keep the
blower running for 5 minutes after shut down.
All the features you mentioned work well.
It still has the original Eimac tubes.
Oh....it came with some bogus set of chimneys so I took them back and
demanded proper chimneys which they promptly forked over.
The down side if there is one is the overload relay.
They just are not available....but then I haven't needed one either.
Other than that I don't think there are any special components in it.
There are at least 2 different power supply versions and schematics of this
unit.
The changes are meter diode protection and single oil filled lytic instead
of discretes.
I think you will find that the 3K-A has more suds available than almost all
of today's amps and is more rugged and better built than any amp from 30
years ago.
This amp is limited only by the available drive wattage.
Typically, if your exciter has enough power to drive the unit to 280ma on
the grid, you can tune and load to 1A @ 4KV.
Truly a California KW.

Regards

Dave Harmon
K6XYZ[at]sbcglobal[dot]net
Sperry, Ok.

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Jim Barber
Sent: Sunday, August 02, 2009 8:10 PM
To: AMPS
Subject: [Amps] Henry 3K-A 'gotchas'?

Any fatal flaws or (significant) bad design decisions in the Henry 3K-A?

After squinting at the schematic available at the BAMA site for a while 
what I see so far is:

(1) A rather unusual "manual" soft-start circuit

(2) The grid metering is done directly, for some reason...?

(3) Operating bias looks to be established with a zener, but I really 
don't understand the combination of RF choke and feedthrough cap that 
appears to short the filament transformer center tap to one side of the 
filaments... I must be looking at that one wrong!?

Any comments, stories etc?

Thanks,
Jim, N7CXI


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