[AMRadio] 4-400 first made when?

Bill Smith hbco2 at sbcglobal.net
Fri Mar 23 16:31:55 EST 2007

----- Original Message ----- 
From: <cemilton at aol.com>
To: <amradio at mailman.qth.net>
Sent: Friday, March 23, 2007 1:09 PM
Subject: Re: [AMRadio] 4-400 first made when?

> Brad and the group,
> My posting said 20J................no such animal to my knowledge.  My
> age is allowing the thoughts of the 20V2 and the 300J to run together.
> I should have said, "the transmitter was a Collins 300J and the upgrade
> made it a 20V-2."  Now I feel better.  I'm reasonably sure we changed
> some iron but thats been a long time ago.  We did add a Rube Goldberg
> designed homebrew solenoid arrangement that allowed use of the power
> cutback switch.  The station ran 1kw day, and .25kw night.  The
> transmitter was remotely controlled and if I remember correctly, the
> R/C unit was made by RUST, Corp..  I'd suggest getting a schematic of
> the 20V-2 and comparing it with the 300J to make your restoration a bit
> easier.
> Funny, I can still remember the Ep , Ip and I (ant) plus the antenna
> resistance.  1500v, .225a, .73a and 470 ohms. (.25kw readings)
> For the 1kw power setting they were  3100v, .455ma, 1.49a and 470 ohms.
>   I must have read those meters hundreds of times.  We were always wary
> of an FCC visit.  And we had one or two while I was CE.
> Those were the days.  Brad, if you were close by I'd volunteer to
> assist in bringing the old transmitter back to life.  They were
> excellent pieces of gear.
> Gud luck es 73
> Chuck

It is funny.. I have a terrible memory for names, can't remember a name 3
seconds after I have heard it.  But the 550A-1 meter readings (3870 KHz)
are, from memory:  Ep, Ip, I(ant) and antenna resistance: 2000v, .225a, 2.6a
and 50 ohms (375 watt reading).  For the 1kw power setting they are 3000v,
.500a (nominal), 4.9a and 50 ohms (1kw).  Naturally, the transmitter is run
at the 375 watt level.  They are excellent transmitters.

Interestingly, the transmitter runs with filaments on most of the time it is
on at all, but the 4-400's have actually improved with use.  They were
80%'ers but now put out better than full power.  Guess they like Amateur AM
service.  If I keep running them, think they'll reach 130%?


73 de Bill, ab6mt
hbco2 at sbcglobal.net

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