[ARC5] First Post and Questions

Thu Jul 13 11:11:53 EDT 2017

Update on the BC-457A transmitter:

I am in still in the process of getting the transmitter ready for putting
on the air on the 60 meter band.  I am making progress and am happy with
how it's going so far.  I do not have the oscillator functioning yet (I am
delayed building my power supply)

Up to this point these are the modifications that I can see that someone
has done to the transmitter:

     1) replaced the original power connection socket at the rear with an
octal socket.  Said person marked each pin connection on the socket with
information as to how the octal socket is now hooked up.  Here is the
information:

         Octal Socket - Power Connection

      Pin #:                           Marking:

        1                                 Ground/Earth

        2                                      "        "

        3                               High Voltage - 450 volts DC positive

        4                               B+  300 volts DC

        5                               B+  200 volts DC

        6                               No connection

        7                               Heaters

        8                               No connection

One other modification that I see is related to relay K 53 (the relay that
switches 200 volts DC to the oscillator and magic eye tubes as well as the
cathodes of the 1625 finals to ground)  Someone has bypassed both sets of
the points with jumpers across the points so that the circuits involved are
always in the "On" position electrically (power is always applied to the
oscillator and the cathodes of the finals are always grounded)

It is easy enough to remove the jumpers from the K 53 relay if I want to
(and at this point I want to).

What I would like to know is the following things:

  1) in the original set up of the transmitter, when the operator was using
CW, what was the code key controlling?  It appears to me that the code key
was not controlling the antenna relay or the oscillator relay.  Those, as I
understand it, were already in the "On" position via the Operate function
on the control module.

I thought I remember hearing or reading in the past that the high
voltage/plate voltage was switched off and on during CW operation.  If so,
then I would assume that the relay to do that switching was in the controls
ahead of the transmitter.  I remember that the unit was powered by a
dynamotor and it supplied the power to the transmitter (probably with the
exception of the 24-28 volts DC for the transmitter's filaments and
oscillator and antenna relays solenoids)

  2) was the screen voltage on the 1625 tubes also switched at the same
time as the plate voltage for the same tubes?

  3) was the oscillator running continuously when the transmitter was used
in the CW mode?

Any help related to these questions would be greatly appreciated.

After watching the YouTube videos related to command set transmitter
restoring and operating, it appears to me that he operated his rig in the
video by

         1) continuously powering the B+ to the plates and to the screens
of the 1625s

         2) inserted the code key in series with the ground side of the
oscillator and cathodes relay and keyed that relay (he bypassed the antenna
relay)  This would have started and stopped the oscillator and grounded the
cathodes of the finals indirectly via the finals.  To reduce chirp in the
transmitter, he recommended "adjusting" the points closure in the
oscillator relay so that the oscillator's points closed before the
cathode's points.

Can someone on the list confirm that?

I have read previously that the best way to operate the transmitter in CW
mode, sans the normal method of using the control unit and dynamotor, is
controversial.  The method on YouTube that I saw is probably acceptable in
my case but I thought I would ask and see what the reasons for the
differences of opinion are.

73 de AK4JA

On Tue, Jul 4, 2017 at 5:33 PM, Leslie Smith <vk2bcu at operamail.com> wrote:

>   Sorry Neil!  My apologies!  For some reason I believe you started the
> article.  You always seem to have "the good oil".  Also, yesterday I found
> your first (ever) posting on this list.
>
>    73 de Les Smith
>    vk2bcu at operamail.com
>
>
>
> On Tue, Jul 4, 2017, at 22:43, AKLDGUY . wrote:
>
> Leslie wrote: "Also, Neil wrote (in Wikipedia) that there are 3 different
> versions of these sets - (or four if you count the "K" series) and there
> are significant (but small) differences between the versions."
>
> I did not write the Wikipedia article, but I have contributed to it. What
> you mention was pretty much done before I even started.
>
> 73 de Neil ZL1ANM
>
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