19-07-2020, 06:47 PM
(This post was last modified: 19-07-2020, 06:58 PM by Mike Watterson.)
The SW that is 50m to 40m (about 6 MHz to 7 MHz) is about 4MHz max. The 38 m to 20 m OC1 band is similarly about 1/2. (About 7 MHz to 14Mhz)
The MW & LW seem close to reality on LO, just deaf.
But first why no LW 252? There should even be BBC R4L, even if noisy. We'll see if anything on MW at dusk. I just sorted a 1935 McMichael 235 "Short Superhet". Hand capacitance about 10cm from the giant RF coil tower starts to bring in BBC R4LW. It's got a 2 m long wire as aerial now in the kitchen. It's one of these mad RF circuits MEANT for a short wire, it's rubbish on even a big loop. I did have stability issues till I bent a piece of coffee tin as a giant flat spring against the IF amp valve and final IFT. I guess the metallisation isn't connecting to the thin wire at the base, which I can't actually see. Massive air-cored 128.5 kHz IFTs . The double diode output pentode looks like a transmitter valve and is quite bright.
Maybe I'll try measuring resistances of RF paths in LW & MW tomorrow, except the tags of the switches are pretty inaccessible.
This is what one should look like: https://www.radiomuseum.org/r/pygmy_club_2.html
The older model is obvious from lack of any visible wavechange, it's on the rear. https://www.radiomuseum.org/r/pigmy_club.html
The "black" background is simply the hardboard everything is riveted to. I'd want to polish and varnish the brass scale cursor.
However unless something I've forgotten, or it's just the band switches, then it's for display only. I've always had trouble with band switches on Roberts like R600 and R700. I've one that's still intermittent.
Anything steel is rusted on the Pygmy Club. Also all the B7G connectors (power and 4 x valves) had the sort of corrosion you see only on battery sets, I guess vapour from dying cells.
The MW & LW seem close to reality on LO, just deaf.
But first why no LW 252? There should even be BBC R4L, even if noisy. We'll see if anything on MW at dusk. I just sorted a 1935 McMichael 235 "Short Superhet". Hand capacitance about 10cm from the giant RF coil tower starts to bring in BBC R4LW. It's got a 2 m long wire as aerial now in the kitchen. It's one of these mad RF circuits MEANT for a short wire, it's rubbish on even a big loop. I did have stability issues till I bent a piece of coffee tin as a giant flat spring against the IF amp valve and final IFT. I guess the metallisation isn't connecting to the thin wire at the base, which I can't actually see. Massive air-cored 128.5 kHz IFTs . The double diode output pentode looks like a transmitter valve and is quite bright.
Maybe I'll try measuring resistances of RF paths in LW & MW tomorrow, except the tags of the switches are pretty inaccessible.
This is what one should look like: https://www.radiomuseum.org/r/pygmy_club_2.html
The older model is obvious from lack of any visible wavechange, it's on the rear. https://www.radiomuseum.org/r/pigmy_club.html
The "black" background is simply the hardboard everything is riveted to. I'd want to polish and varnish the brass scale cursor.
However unless something I've forgotten, or it's just the band switches, then it's for display only. I've always had trouble with band switches on Roberts like R600 and R700. I've one that's still intermittent.
Anything steel is rusted on the Pygmy Club. Also all the B7G connectors (power and 4 x valves) had the sort of corrosion you see only on battery sets, I guess vapour from dying cells.
