70H3 Collins PTO

[KC2ZFA]

Hello all,
I came across this 70H3 PTO for $15 shipped and couldn't say no...

It came with the attached schematic. I have scoured the web and I've gotten
some conflicting info: the 70H3 covers either 1.5-3.0 Mc or 2.0-3.0 Mc.
Does anyone know its range for sure ?

Also, does anyone know what B+ is appropriate for it ? I found the answer to this: 150 Vdc

If you look at the schematic, the suppressor grid of the buffer (pin 2) comes out to
the plug. Am I correct in thinbking this is so that a sufficiently negative voltage will
shut off the buffer during keying or T/R ?

Any info welcome, Peter

ps. I also found an archived e-pay sale for a 160M exciter (2nd pic) that uses this pto.

[WA8DRZ]

That PTO is from a T-368 transmitter and my reading of the TM for it says the range is indeed 1.5 to 3.0 Mc.

Craig

[KC2ZFA]

Thanks Craig...yes, it's similar to the one in the 368 but apparently the one I have is from the T-195...

How did I find out ? I searched for 70H-3 not 70H3...Doh!

One thing: when searching for 70H3 a few pto lists come up which contain
erroneous information.