Hi Albert,
?
I was wondering whether there might be something wrong with the cable grounding since you can influence the output amplitude when placing a hand nearby.
Patrick Wong AK6C
---In TekScopes@..., <aodiversen@...> wrote:
Some time ago I reported that this 65-500 MHz GR-based oscillator had a nice flat frequency response. But at present the output amplitude is about 10% too high in a small region around 465 MHz. When I hold my hands at the head side cable end, or around the head, then the output amplitude (at an S-2) changes some 5-10%.
I found the hand effect also when feeding the disconnected cable with the output of my 220-900 MHz oscillator. That way I could observe that the diode detector voltage (measured inside the main unit) change relatively even more than the output amplitude. The effect on the output remained after disconnecting the detector diodes (that is after desoldering the 62R series resistor).
Now I was thinking of standing waves in the 5 ns cable, but the mentioned effect is only clearly present around 465 MHz. I also don't see why standing waves would have a different effect on output amplitude and detector voltage.
Any idea what could be going on here?
The detector head is the same as in the 067-0532-01 version of which a nice pdf is available at Tekwiki.
Albert
