YES, that RCA phono jack is indeed the PTO output, and it should be in the
range of 5 to 5.5 MHz.
If you don't have any signal on the frequency counter, AND YOU ARE SURE YOUR
COUNTER IS WORKING, then your PTO is not working.
THE FIRST THING TO DO is to make sure the counter is working.
You can check this on the SSB Board (80449) by measuring at the junction of
R16 and R17 in the emitter circuit of Q3. You should see (approximately) a
9 MHz signal there.
Then double check the Phono jack coming out of your PTO.
Check that it has 5 MHz on it.
To measure the signal from the PTO, insert a new Phono Plug (with its shell
removed) into the Jack and measure its center pin. Or, remove the cover
from the PTO and measure directly on the jack, inside the box.
You MUST be able to measure a signal there; otherwise the PTO is not
When going through the schematic of the 80278, NOTE that there is a mistake
on the page (3-12).
On the top it shows the 4 pins coming out of the box. The two in the middle
are BOTH labeled "VFO REG.".
The one on the left is the VFO REG., the one on the right is the "VFO SHIFT"
(voltage coming from the OSC. MIXER board).
There is a second mistake in the schematic, on Page 3-6 showing the wiring
of the entire radio. On this page TT forget to draw any +Voltage going into
the PTO. I have never worked on the PTO, other than to adjust the
frequency, so you will have to ask someone else what voltage connects to it,
but it is probably the regulated +8v and I guess it must enter on the pin
labeled VFO-REG (the one on the left).
YES, you must have continuity between the center wire of the phono plug
which plugs into the PTO, and the Phono Jack "VFO OUT" on the back panel.
I'm sure you do. Sounds like the VOM is not making a clean connection the
plug's center pin. When I'm measuring on older radios, I use probes with
points sharpened as sharp as a needle. That way I am sure I make contact.
Careful; I rarely manage to measure without drawing blood! ;-)
Gud Luk, Mike.
From: firstname.lastname@example.org [mailto:email@example.com]
On Behalf Of Michael Silevitch
Sent: Wednesday, February 22, 2012 3:35 AM
To: Discussion of Ten-Tec Equipment
Cc: Michael Silevitch
Subject: Re: [TenTec] Omni C
I'm confused at this stage. I connected the frequency counter to the RCA
phono jack which is, I believe, the PTO output. This jack is located on the
top of the VFO box in the left rear corner when looking at it from the
front. The counter doesn't display any reading. Also when I did a continuity
check between the cable that was connected to the RCA socket on the VFO box
and the VFO OUT socket at the back of the rig, I din't have continuity.
Am I right in assuming that the RCA socket on the VFO box is the VFO output?
If not, then it would explain my confused readings. If so, then I will sleep
on it, tomorrow is another day!
On 2/21/12 12:16 PM, "Joe" <firstname.lastname@example.org> wrote:
>That should tell you if it is the PTO, and you can proceed from there.
>I will be listening and looking.
>----- Original Message -----
>From: "Michael B. Silevitch" <email@example.com>
>To: "'Discussion of Ten-Tec Equipment'" <firstname.lastname@example.org>
>Sent: Tuesday, February 21, 2012 11:13 AM
>Subject: Re: [TenTec] Omni C
>> Dear Joe
>> I obtained a loan of a 80MHz frequency counter and a 100MHz scope.
>> I'll use these instruments to get more info on the signals. I will be
>> out of town starting tomorrow so I will probably only be able to get
>> to this after Sunday. If need be I'll get a signal generator as well.
>> -----Original Message-----
>> From: email@example.com
>> On Behalf Of Joe
>> Sent: Tuesday, February 21, 2012 10:51 AM
>> To: firstname.lastname@example.org; Discussion of Ten-Tec Equipment
>> Subject: Re: [TenTec] Omni C
>> Having built a VFO which does everything that the 243 does and more,
>>I can tell you how that unit works with the Corsair II and other
>>transceivers which have the ENABLE pin on the PTO. The OMNI obviously
>>does not have the ENABLE pin nor the E signal, so things are
>> The 243 works with the Corsair II as follows. The accessory jack has
>>an E pin, the PTO ENABLE. When the 243 is connected to the accessory
>>jack, it connects and disconnects the 8 volt regulated voltage from
>>the E line going back to the Corsair as desired depending on whether
>>or not the PTO should be
>> on. For example when working split, the remote would be on during
>>transmit for example and the PTO would be off and vice versa for
>>receive. When using the remote for both Tx and Rx, the PTO would be
>>simply turned off, ie, the E
>> line disonnnected from 8 volts. When receiving simultaneously, both
>>the PTO and the remote are on and the two signals are added before
>>being output to the Corsair and thus both frequencies can be
>> This are apparently different in the OMNI C. I would guess that the
>>243 has a means of switching the PTO output, which is apparently
>>always present at the VFO OUT jack. By switching the PTO as well as
>>its internal VFO signal, the same thing must be accomplished. I have
>>not studied the schematic to see
>> how it is actually done, but reed relays or diode switching would
>>seem to be
>> In order to proceed with troubleshooting this problem, we need to
>>know if there is any output from the VFO. Alternatively, if a 243 is
>>available, it could be hooked up to see if the receiver works.
>> ----- Original Message -----
>> From: "Lee WA3FIY" <email@example.com>
>> To: "Rick - DJ0IP / NJ0IP" <Rick@DJ0IP.de>; "Discussion of Ten-Tec
>> Equipment" <firstname.lastname@example.org>
>> Sent: Tuesday, February 21, 2012 9:09 AM
>> Subject: Re: [TenTec] Omni C
>>> OK. I have three drawings here regarding this VFO question, Omni A-D
>>> download manual,
>>> Model 243 Remote Vfo Manual (Manual states it is for the Omni series
>>> transceivers) and
>>> Corsair II.
>>> All three show a Molex 9 pin accessory connector. That's common.
>>> Common pin assignments are:
>>> pin 1 - T voltage
>>> pin 2 - plus regulated voltage
>>> pin 3 - plus 13 volts
>>> pin 4 - shift (Omni it is called REM VFO) pin 8 - ground
>>> Different pin assignments are:
>>> pin 5 - local oscillator out (for frequency counter) pin 6 - relay
>>> common pin 7 - relay normally open pin 9 - relay normally closed
>>> 243 VFO:
>>> pin 5 - local oscillator in
>>> pin 6 - no connection
>>> pin 7 - no connection
>>> pin 9 - no connection
>>> Corsair II:
>>> pin 5 - R voltage
>>> pin 6 - Corsair VFO enable (note indicates this pin must be jumpered
>>> to pin 2 when remote
>>> vfo is not being used.)
>>> pin 7 - relay normally open
>>> pin 9 - relay normally closed
>>> (relay common is internally grounded in Corsair)
>>> Hope this helps.
>>> On 21 Feb 2012 at 14:17, Rick - DJ0IP / NJ0IP wrote:
>>>> Gary, the 243 is the wrong radio and the wrong manual.
>>>> That's for the old Triton, which was different.
>>>> It had the Octal Jack on the back and indeed pins 6, 7, and 8 were
>>>> for the VFO.
>>>> Mike has an Omni C.
>>>> It has a 9-Pin Molex accessory socket on the back and totally
>>>> different signals on it than the 243's accessory jack.
>>>> I have a hard copy manual for OMNI A and D on my desk.
>>>> I have the downloaded OMNI C on my screen.
>>>> Both are identical and Mike (Brice) already posted the signals that
>>>> are on it. There is NO JUMPER required for the VFO management.
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