01-07-2012, 12:04 AM
Hello Alan, the osc injection signal has been amplified, basically what I have is a 1 Mhz osc signal which is derived from a B40D, I did a reversable mod (no soldering) in order to get the B40's local osc down to 1 Mhz when that receiver is tuned to the bottom end of the MW band, that is fed to G1 of a single pentode stage (the harmonic generator) through a low value cap with grid leak, according to my DMM the DC voltage on the grid is -ve 11 volts, It appears to be working in class C, the anode load consists of a tunable parallel tank, this is tuned to the harmonic required to select the band on the project I am working on which is basically a regenerative converter receiver.
The harmonic from the tank is fed to G1 of the mixer, G3 is the incoming signal, if I select the 10th harmonic with the tank, the voltage on the grid of the mixer is approx -ve 4volts DC but this is approx as my cheapo DMM is not very good, the mixer will actually work direct fed from my sig gen at an output of only 200 mv.
Obviously the lower the harmonic the higher the peak to peak is and the visa versa.
I only have one mixer valve to hand, although it works it is probably not the best one for this particular job.
Lawrence.
The harmonic from the tank is fed to G1 of the mixer, G3 is the incoming signal, if I select the 10th harmonic with the tank, the voltage on the grid of the mixer is approx -ve 4volts DC but this is approx as my cheapo DMM is not very good, the mixer will actually work direct fed from my sig gen at an output of only 200 mv.
Obviously the lower the harmonic the higher the peak to peak is and the visa versa.
I only have one mixer valve to hand, although it works it is probably not the best one for this particular job.
Lawrence.
