[Amps] Step Start on a 3KA Amp

[Harold Mandel]

There are all sorts of delay relays available in the commercial electrical
market.

All elevators use these plug-in devices. The modern ones run on a.c. or D.C,
and
from 24 to 240 volts, all on the same terminals with no jumper changes.

Most of them are made to fit octal tube sockets, and some of the newer ones
fit
DIN rails. 

These come with adjustable settings on the top. Some come with
range settings that can go from Ø to 1 second, 1 - 10 seconds and 
also in minutes and hours.

Looking at the D.C. anode voltmeter swing up on my power supplies
1/2 second does not leave time for everything to normalize and the
delays were set to five seconds. The voltmeters are then stable before the 
contactors release.

  Hal Mandel 
W4HBM
 
-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Phil Clements
Sent: Tuesday, September 19, 2006 3:07 PM
To: amps at contesting.com
Subject: Re: [Amps] Step Start on a 3KA Amp


> 
> Sounds a bit primitive - no wonder it needs that big resistor! With so
> many well-known ways to make a completely automatic step-start, it seems
> a really strange decision to use a manual switch and leave the whole
> thing wide open to operator error.

Many of the Henry amplifiers were sold to Government and Commercial users.
They were in U.S. Embassies all over the world. Henry assumed that the
operators would read and adhere to the manuals. If you have not operated one
of the Henrys, it may seem primitive to you, but in practice, one just
rotates the mains switch from off to on in a normal manner. The travel in
the rotary switch from off to its final position of on gives the proper
amount of time for the step-start to function properly. The operator did not
have to give this any thought...just turn it on! It worked well for decades
until the amps fell into the hands of folks who did not read the
instructions, or didn't get a manual with the radio. This "primitive"
circuit has only one moving part; the very robust a.c. mains switch. If one
did fry the cone heater, it could be replaced as easy as a light bulb.
Sometimes K.I.S.S. is a good route to take if you are in primitive
territory.

(((73)))
Phil Clements, K5PC



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