a few questions here. I have this frequency display:
http://www.pongrance.com/ddfc.htmlI also have this preamp:
http://home.att.net/~jacksonharbor/preamp2.htmThe input impedance on the frequency display is too low so I added the preamp with FET input ~10meg. Here is the problem.
I cannot find a really good point to get the HFO. I have done the following:
1) wrapped wire around the 12at7 oscillator and connected that to the preamp. Signal level is too low
2) Connect the preamp to the cathode of the HFO (pin 3 of the 12at7). This works, but the pulls the oscillator way too much
3) Connect the preamp to the cathode of the HFO Cathode Follower (pin 8 of the 12at7). This also pulls the oscillator, but not as much. Well, as I go up in frequency, it pulls more.
4) Connect the preamp to the grid of the 1st mixer (pin 7 of the 6cs7). This still pulls the oscillator (wtf?).
Is there any point that I can connect this to that will not pull the oscillator?
Should I maybe connect to the plate? Also what should the rf voltage level be? On the cathode it is less than a volt.
Tom - AB3FL