Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Boyd -
OK. I believe that white/red wire "flying" is connected at the other
end to R140, the 15k, 7W dropping resistor. You can verify that with an
ohmmeter check. If you check, I bet you'll measure +150VDC regulated on
that wire with it disconnected like that. This is the current source
that drives the PTO and its internal 10V Zener. There's probably an
"empty" tag on that small board where it can be tied to the white/red
wire coming from the PTO, and nothing else.
The center conductor of the coax should be connected to one end of a 100
ohm resistor, and the white/green wire from the PTO goes to the terminal
on the "other end" of the resistor.
The terminal at the center-bottom of the board is ground, and the
white/black wire from the PTO connects there.
IF the white/blue wire connected to the board is one end of a 22k
resistor, AND there is a fourth wire (color unknown) coming out of the
PTO, that wire connects to the "other end" of the 22k resistor.
Garey - K4OAH
Boyd Van Horn wrote:
Garey, Here are a couple pictures of the TR-4 I am asking about. Boyd
W0BUW
*/Garey Barrell <[EMAIL PROTECTED]>/* wrote:
Garey Barrell made an utterance to the drakelist gang
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Boyd -
Well, first of all, that's gotta be a TR-4, not a "C". It would be a
Version 2 model.
There's always "one".... :-)
Any chance of a photo of the board? Anything else on that board
except
the parts you listed?
I can make a guess from what you have told me so far...
The Red (or White/Red) wire from the PTO should go to the terminal
that
also has a White/Red wire that is connected (via the harness) to
R140,
which is shown on Page 14. You should be able to verify that with an
ohmmeter check. Also, in this version, you _should_ be able to turn
on the transmitter with the PTO out and measure +150V regulated on
that
terminal. A cross check with the ohmmeter should read very close
to 15k
ohms from that terminal to the +150V bus.
The White/Green wire from the PTO should connect to the terminal that
goes to the 100 ohm resistor on your board. The other end of that
resistor should go to the coax that goes into the harness, and is the
PTO output.
The White/Black wire from the PTO should connect to chassis ground,
probably to a terminal on your board.
There "may" be another wire from the PTO, I don't have a TR-4 here to
check, and have no idea as to the color code. But if you have one
"left over", it would connect to that 22k ohm resistor. The other end
of that resistor goes to Pin 2 of the RV-4 connector. I don't know
much
about the RV-4, but it looks like that Pin 2 is grounded or "open"
for
"normal" transceiver operation, and applies a positive voltage to the
internal PTO to disable it and allow the RV-4 to control. My
understanding is that the transceiver should operate normally with
the
RV-4 unplugged, which would leave that lead "floating", e.g., even if
that wire were not connected to the 22k resistor the transceiver
should
work normally without the RV-4 plugged in.
Let me know!!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
Boyd Van Horn wrote:
> Gary, I purchased your best CD from you and love it. However, I
have a
> TR-4 C that is serial number 23470, that has a different pc boad
than
> any of your pictures. It is adjacent to the VFO jones plug
toward the
> filter cap. It has a .02 cap along with a 100, 22K, and 330 ohm
> resistor. I have PTO problems with this unit. It will tune using
the
> external VFO, but not the internal one. I made a note where all the
> wires go when I pulled the PTO, but have lost it so I need some
sort
> of picture to help. Got any ideas ? Boyd W0BUW
>
> *//*
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