posted & mailed

Bob wrote:

ken scharf wrote:

Early SSB exciters used the 7360 tube as a mixer / vfo so I know this
type of tube will work as a self excited converter. As far as pulling
is concerned this would depend on the difference between the oscillator
and IF frequencies, or the oscillator and signal frequencies. But
pulling shouldn't be any worse than with the pentode mixers that
coupled the oscillator to the same grid as the signal input. At least
the 7360 isolates the signal and oscillator to different electrodes.
Also the signal input is balanced and shielded by the screen grid.
OTHO I don't know how good (stable) an oscillator this tube is.
Probably better as a crystal oscillator than a vfo.

The very /best/ mixer I ever made used the 7360.

I tried several other types of valve ("tube" - U.S.) mixer, but /nothing/
came even slightly close. The isolation of the local oscillator from the
incoming signal, the conversion gain, the accuracy of balance and the
bomb-proof nature of the mixer made it superior to /anything/ else I've
ever tried. In my receiver, there's a front-end amplifier, using a
variable-mu pentode then the 7360. It handles a bigger dynamic range
than /any/ other mixer.

The VFO is a "Kallitron" type, using two FETs and a PIC-based
huff-and-puff stabiliser (in 10 Hz steps) and two bipolar buffer
amplifiers to drive the
grids of the 7360. The PIC also drives an LCD display of frequency, and
frequency stability is spectacular.

I can assure you - /there/ /is/ /no/ /substitute/ for the 7360. Simply
don't consider /anything/ else. Professionally, I've worked extensively
on "H-mode" switched mixers - often using very advanced components - and
can tell you that the 7360 out-performs /everything/ else!

One other thing - self-excited mixers /never/ perform well. You should
re-think your approach.

Chris