[TMC] 750 help thanks

[Roy Morgan]

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 --