The PTO needs very good buffering. Otherwise the signal drops and sensitivity is reduced significantly. I used an FET as a source follower with 50 ohms. So you can connect standard coax.?
Of course to feed your FS4B, Gary! ?
73, Dieter DL5RDO
Von meinem iPhone gesendet
toggle quoted message
Show quoted text
Am 07.01.2025 um 22:23 schrieb Gary WB6OGD via groups.io <winbladgary@...>:
?
If you don¡¯t really need to see the MHz,?
you could tap the PTO signal, it is larger
and is the same for all bands.
73,
Gary?
WB6OGD
On Jan 7, 2025, at 10:05?AM, Paul Christensen via groups.io <w9ac@...> wrote:
?
Possibly consider a J310 JFET as a common-source amp placed right at the source of the INJ jack. Resistors chosen for a gain of A = 2 (6 dB) to get over the minimum RF sample voltage requirement. ?
?
The JFET unloads the INJ line to the Hi-Z gate and that isolates the INJ source from cable capacitance to the freq. counter.? With adequate PS decoupling, probably a half-dozen parts are needed, mounted either on a 5-6 lug terminal strip or Vector board.?
?
The common I.F. output buffers often seen are common-drain source-followers with a gain of less than 1.0.? That won¡¯t work in this instance to solve the problem.?
?
Paul, W9AC
