29-07-2022, 06:09 AM
Hi Adrian,
I haven't advanced far with the mixer, mainly due to my lack of test equipment for VHF frequencies. My signal generator has a dead band between about 38 and 90 MHz and my scope is almost out of steam at 100 MHz. Your talk of VHF did prompt me to think again. I made the mixer originally as I had made a 455kHz mixer, which does work well, but got sidetracked with FM and 10.7 MHz due to coming across a 6BN6 which seemed to be an ideal for simple FM demodulation (another story). I progressed a little with testing a dual band IF stage but really need to build a local oscillator for FM.I was thinking the other day and did come up with what I thought a good physical construction for VHF. If you are interested - A sort of bobbin layout with the valve screening tube in the centre soldered to manhatten layout surface mount washer looking discs at either end for the components. The valve connections coming out of the holes next to the board for short and easy connection to the rest of the circuitry. I have yet to determine the oscillator details though. Until I get this made though I think I will be fighting against the elements to prove anything but will keep going and keep you updated with progress.
Tracy
I haven't advanced far with the mixer, mainly due to my lack of test equipment for VHF frequencies. My signal generator has a dead band between about 38 and 90 MHz and my scope is almost out of steam at 100 MHz. Your talk of VHF did prompt me to think again. I made the mixer originally as I had made a 455kHz mixer, which does work well, but got sidetracked with FM and 10.7 MHz due to coming across a 6BN6 which seemed to be an ideal for simple FM demodulation (another story). I progressed a little with testing a dual band IF stage but really need to build a local oscillator for FM.I was thinking the other day and did come up with what I thought a good physical construction for VHF. If you are interested - A sort of bobbin layout with the valve screening tube in the centre soldered to manhatten layout surface mount washer looking discs at either end for the components. The valve connections coming out of the holes next to the board for short and easy connection to the rest of the circuitry. I have yet to determine the oscillator details though. Until I get this made though I think I will be fighting against the elements to prove anything but will keep going and keep you updated with progress.
Tracy
