On Wed, 27 Aug 2008, Graham wrote:

Ive seen it proposed that you connect to the valve anode .via a high
voltage cap ...never tried . looked a bit risky with 3/4 kv of rf ..
but i suppose that would prevent the 'suck out' from the pi tank
cct .. the rx would be looking through the cct , as long as the vlave
was biased off .. not too much noise ?

G ..

I thought that was the common form, certainly in homebrew articles
that seems to predominate. Yet, the commercial ones are likely to
be standalone, so one doesn't have to fuss with the transmitter.

I've never used one, and never given it much thought. I thought
the suckout issue was when it was connected to the plate of the
transmitter, but that's more likely because the suckout issue
was a common issue with TR switches, and I was more familiar with
connecting it to the plate of the transmitter's output tube.

One thing, it certainly was not uncommon to see articles where
the TR switch included a stage of amplification and a tuned circuit
of some sort.

Also, when connecting to the plate, they'd use a very small value
capacitor, and one article I just checked said to use an even smaller
value for a higher power transmitter. That's going to cause some sort
of loss, indeed that article mentioned one might need to add a tuned
circuit to the TR switch to compensate for the loss.

MIchael VE2BVW