[TMC] FW: Re: SBT-1KV lives!

[Duncan M. Brown]

{I copied this to Greenkeys instead of TMC.  Maybe I should go back to bed!}

> [I started this reply this AM, then got interrupted.  When I came back to
finish it, it was gone, so had to do it over again!]
>
> Larry,  I had found your comments on firing up a SBT-1K in the TMC-list
Archives of a few years ago.  They were very helpful in getting my
check-out started and watching the screen grid current closely.
>
>
> > [Original Message]
> > From: <TELEGRAPHER at att.net>
> > To: <duncanancy at earthlink.net>
> > Date: 04-Feb-09 00:34:57
> > Subject: Re: [TMC] SBT-1KV lives!
> >
> >
> >  I've got one here SBT-1KJ) that i went thru similar problems with. 
When you turn on the juice you'll find that the antenna really if hooked up
will activate.  This is the same thing with the PAL-350 and 500 units as
well.  
> >
> > What i';ve found out is that until i key the mic there is no RF
generated.  When i do key the mic it activates a relay in the power supply
which then allows the generation of RF.  I suspect that these units because
they operated split frequency had the HV on all the time and the only thing
that happened when the mic was keyed was a relay activated causing the unit
to generate RF.  I've not dug into it further to see what relay it is that
operates when the mic is keyed.  It certainly is better for the unit to
ahve th HV and Plate voltages on all the time though.
> >
>
> The mic keys the exciter directly, but it needs to turn on the HV & Ant
relay, too.  I have three different manuals.  I'm hoping I can figure out
from them where to get the control needed.
>
> >
> > There is no antenna realy associated with these.  If you require one,
and for simplex operation on the ham band you certainly do, then you would
need to hook one up using the Antenna relay terminals which throws 115Vac
out for that purpose.  
> >
>
> According to TMC TB 1001A, the SBT-1KJ does not have a T-R relay, but the
others do.
>
> >
> > Once again, turning the HV on and off makes it a bit ruff on those
relays and circuit breakers in the power supply.  My unit had a couple of
bad 872 rect. units as well as a couple of interlocks that were
intermittant.  
> >
> > 800W output?  I hope you were in CW mode.  Certainly not meant to do
more than 250W out in AM,1 KW SSB PEP!  That is the tube ratings.  I think
i saw about 650 out on mine before the CB dropped out.  The grid current
should not go about 5 ma.  
> >
>
> Yes, that was CW, no modulation.  I was just using the Mic to key the
exciter.  For AM operation, plan on setting it to about 200-250 watts out. 
I still need to check on the some of the internal adjustments (voltages &
trip currents) in the PS-4.
>
> >
> > Also there is a capacitor in the MV power supply that is on the Screen
voltage line i believe that should be changed out.  I'll have to look that
one up to see just which one it is but if it goes, so will the tube and
they ain't cheap.  I found a couple of new ones over in Iceland for $300
per, still in the sealed boxes.
> >
>
> Let me know which capacitor it is.
>
> >
> > My SBE-2A works fine on USB but will not work on LSB.  I suspect the
xtal or something has happened inside the sealed LSB unit.  Not sure how to
handle that one.  MY VOX is setting here in the shack awaiting it's turn on
the bench.  Will probably disconnect the oven wiring to save power and then
let it run continuously.  
> >
>
> On my "SBE-6" (unit looks like a "SBE-9", maybe some one got the modle
number stamp upside down??)  the sidebands are both generated by a comon
250 KHz crystal.  I think it is the same in the SBE-2, except the crystal
frequency is slightly different.  If you have USB, the crystal must be OK. 
Maybe the problem is in the LSB filter??
>
> >
> > Anything else i can help with?  John Kopke sent me picture sof your
unit.  Very nice.
> >
>
>   THANKS!
>
> 73, Duncan K2OEQ
>
>
> > Larry
> > W0OGH
> >