[TMC] 750 help thanks

[John Russo]

Hello Roy,

I would be intersted in some of the details of the modulator you are testing in a
750 GPT.

I have a 750 in storage and will someday get around to building a modulator for it.

    Thanks,  John Russo    KF2JQ

Roy Morgan wrote:

> At 09:24 AM 12/20/02 -0700, you wrote:
> >Thanks Doug, Todd and Roy for helping me here on my 750.  I have most of
> >the documentation.  When I bought it I got the manuals directly from TMC.
>
> Jay,
>
> What a novel idea!
>
> >   I was thinking of bypassing the TMC MO for my Collins triple oven time
> > standard that is in one of my URC32s.
>
> Does the URC32 create a variable frequency?  The TMC Master Oscillator
> operates from 2 to 4 mc and is not a crystal driven synthesizer or anything
> of the sort.  For AM and CW you set it to the desired output carrier
> frequency (or subharmonic) for FSK or for use with the SBE, you do not.
>
> >  So both receiver and transmiter are on the same clock.
>
> Nice idea but that may not be needed.. The MO drift specs call for 10 to 50
> cycles frequency change.
>
> >Roy asked what the RF out connectors are.  There are two on the right side
> >of cabinet, the "test" connector which is a so-239 and the main one (can't
> >remember the number at the moment) that is much larger.
>
> The point is that if that "larger" RF connector is the original one as
> supplied on the transmitter, you will be hard put to locate a mate for it.
> it is NOT a normal connector. IT's a quick disconnect unit like on an air
> hose with the innards like a type C connector.  Look at it closely, and if
> you need a cable connector (for RG-8) let me know.
>
> The smaller (SO-239) connector is the output of a capacitive voltage
> divider meant for a scope.  With 250 volts or so RF on the main output at
> 1000 watts, this is needed to give safer output voltages for a scope or
> sepectrum analyzer or whatever.
>
> >  I'm interested to know opinions on operation.  It looks like it is a bit
> > of a chore to change freqs and bands during operation
>
> This thing is meant to be put on frequency and left there.  For months.  I
> think that a practiced operator can re-frequency the thing in 15-20
> seconds. Small changes in frequency can likely be done with no retuning at
> all.  This is not your skip up and down the bands by touching buttons radio.
>
> >   Maintenance looks to be fairly easy.  Aside from URC32s or KWT-6s I
> > have never seen a xmitter that has "all access" like this.
>
> Maintenance? What maintenance.. they just RUN!
>
> This is a nice day for me. I'm off to West by God Virginia to help install
> and test a newly made modulator in someone else's GPT-750.  Soon, I'll make
> one for my transmitter.
>
> "Holy Regulations, Batman!  750 watts AM carrier is more than the legal limit!"
>
> (Oh yes, I see here in the manual, we can reduce the power easily to any
> level desired.)
>
> Roy
>
> - Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
> 7130 Panorama Drive, Derwood MD 20855
> Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
> roy.morgan@nist.gov --
>
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