19-10-2023, 08:59 PM
Well, in 1975 or so I built a test chassis using custom PCBs and MC1496 (DIL) demoing AM, DSBSC, SSB without filters, Phase modulation using DSBSC mod and injecting carrier at 90° and MC1496 as phase comparator for a PLL using TTL divider. To demo communications modulation/demodulation systems.
Nearly 10 years later I did PLL synths in Westinghouse for continuous very wide band sweep using PIN diode switches and multiple VCOs.
Then by 2007 was designing 870/921 MHz duplex (to co-exist with GSM gear at same sites) and modifying existing 10.45GHz duplex gear. The 870/921 MHz duplex gear used strip-line filters at RF and 42MHz IFs with 200kHz and 2MHz bandwidths. NatSemi PLL/Synth chips controlled by PC then PIC programmed in JAL.
I think the G4DTC Ray Howgego "Ultimate" receiver is maybe ultimate in terms of ideas he threw at it and complexity. I'd go for something a lot simpler, even then, and now even though I have all the parts, test gear and workshop I'd not bother. I've tested a 1j29b as have others as a really robust RF front end. It's a rod pentode, which means it's not really a pentode at all and very low noise. Very linear sharp cut off, but G2 varied from 20V to 90V will set gain. Used on Russian military gear from man packs, vehicles, MiG and satellite. Ring diodes or quad IC FET switches for first stage mixing.
Nearly 10 years later I did PLL synths in Westinghouse for continuous very wide band sweep using PIN diode switches and multiple VCOs.
Then by 2007 was designing 870/921 MHz duplex (to co-exist with GSM gear at same sites) and modifying existing 10.45GHz duplex gear. The 870/921 MHz duplex gear used strip-line filters at RF and 42MHz IFs with 200kHz and 2MHz bandwidths. NatSemi PLL/Synth chips controlled by PC then PIC programmed in JAL.
I think the G4DTC Ray Howgego "Ultimate" receiver is maybe ultimate in terms of ideas he threw at it and complexity. I'd go for something a lot simpler, even then, and now even though I have all the parts, test gear and workshop I'd not bother. I've tested a 1j29b as have others as a really robust RF front end. It's a rod pentode, which means it's not really a pentode at all and very low noise. Very linear sharp cut off, but G2 varied from 20V to 90V will set gain. Used on Russian military gear from man packs, vehicles, MiG and satellite. Ring diodes or quad IC FET switches for first stage mixing.
