[R-390] Installing replacement PTO
Tom M.
[email protected]
Mon, 6 Jan 2003 16:15:54 -0800 (PST)
Larry,
You are wise to be cautious. The PTO can be damaged if it installed
improperly.
The PTO has a end to end range of about 16 turns if I recall. The "ten turn"
stop has a range of 10.7 turns. So as long as you set the PTO up reasonably
close to the logical starting point, +/- one turn you will be safe.
If you have another receiver you can listen for the PTO signal.
Hookup the electrical connector and turn on your 390A. Set your second
receiver to 3455 kcs (BFO ON) and listen for your PTO signal as you turn the
PTO dial a little left or right. 3455 will be about three turns clockwise from
the counterclockwise stop (don't be too rough with the stops). 3455 corresponds
to the low end of the range, 2455 is the high end (it goes down as you tune up,
in other words).
Tune around and listen and you should hear the signal. If you don't hear it
you can rig a "transmit antenna" onto the MB connector on the PTO for more
signal.
Of course you could read it with a freq counter if you have one.
Once you have the PTO set to 3455, set the 390A dial to 000 (i.e. the low end)
and hook up your PTO as best the coupler allows you to.
You can then tune to a local AM station of known frequency and check to make
sure it is set up properly. If you don't want to mess with the second
receiver, you can use the local AM station but you'd need to be reasonably
close in the initial setup so that the RF deck is cooperating with the PTO.
Again, set it up about three turns from the counterclockwise stop (so when you
tune up you know you won't be hitting a stop in the PTO), install it in the
390A with the dial at 000, and then check it all against a local AMer.
Cheers
Tom N5OFF
--- Larry and Jody Cogan <[email protected]> wrote:
> I have just acquired a replacement Cosmos PTO. I have no real
> information about it, other than it "was removed from a working
> receiver". Is there a mechanical way to determine if it is set at (or
> near) 2455 khz? The oldham coupler on the PTO was "unrestrained",
> i.e., not taped to prevent rotation, etc.
>
> Thanks, Larry
>
>
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