Hi Chris, You've probably thought of these, but just in case: field strength meter's output voltage is very dependent on temperature and can vary up to 30 %. Is the Helmholtz coil getting a constant
Hi Chris Mmmmm it seems that you might have a problem with the tuning caps, I wonder what sort you used. You have to be a bit careful with cap types in critical circuits. The other though is to try t
Hi Chris the following things occur to me to try 1 the 2N3819 is a juction fet not a mosfet (as with Dick original design) so is probably more likely to show changes in input (gate-source) current wi
Dear Chris, LF Group, Looking at the circuit, there are not that many possibilities for varying gain with temperature. The NE/SA 602/612 devices should be quite stable with temperature - the Philips
Dear Chris, LF Group, The problem's before the mixer. As advised, I disconnected the RF stage and injected a signal into the mixer and it gives a constant output even with a blow heater playing on th
