doubts in wire specifications
I'm finding a good 1000vdc working wire for my GM70 amp project.
I have few meters of Alpha Wire 18AWG 5877 PTFE rated 200C / 1000V RMS (military applicable specifications MIL-W-16878/5 type EE) but also in the same pdf the specifications for AWM/STYLE 1180 says 200C / 300V RMS.
I doubt about if I can use this wire as is or needed a double insulation to avoid corona effect.
Anyone knows how to read these specifications?
I'm finding a good 1000vdc working wire for my GM70 amp project.
I have few meters of Alpha Wire 18AWG 5877 PTFE rated 200C / 1000V RMS (military applicable specifications MIL-W-16878/5 type EE) but also in the same pdf the specifications for AWM/STYLE 1180 says 200C / 300V RMS.
I doubt about if I can use this wire as is or needed a double insulation to avoid corona effect.
Anyone knows how to read these specifications?
-500V Vgk?!have I seen right when noticed a few GM70 schematics with B+ 500V, and -500V bias
have I seen right when noticed a few GM70 schematics with B+ 500V, and -500V bias
If I understand your question - His schematic shows +500 on the plate and -500 under the cathode ccs. The two total 1000VDC. If the current is set to give ~90mA per tube, the circuit will divide the total 1KV to find the ratio of Vccs and Vp-k that work for the GM70. By the curves I have it would be something around 915Vp-k and Vg -85V.
I think 1000vRMS is not safe enough (inductive spikes can go higher). I used 4KV insulated transformers and 4KV rated Pomona wire, from Mouser.
Hello.
Has anybody considered auto-biasing the GM-70 tube with not-a-cathode-resistor, but rather with a 230V/40W or 230W/60W incandescent light bulb ?
Bypassed with say 100uF/200V and (maybe) and additional electrolythic ?
The bulb is a power PTC device, so it will probably do much more than just auto-bias.
It will probably provide some risk of non-symmetrical "negative-feedback", hence that is why I mention the bypass cathode capacitor.
What happens if the bulb burns and opens circuit ? Does 1500V on the anode, with the grid at GND potential, and no cathode current, constitute a hazard ?
There would be an interstage transformer at the grid of the GM-70 ...
Ideas ? / comments ?
Has anybody considered auto-biasing the GM-70 tube with not-a-cathode-resistor, but rather with a 230V/40W or 230W/60W incandescent light bulb ?
Bypassed with say 100uF/200V and (maybe) and additional electrolythic ?
The bulb is a power PTC device, so it will probably do much more than just auto-bias.
It will probably provide some risk of non-symmetrical "negative-feedback", hence that is why I mention the bypass cathode capacitor.
What happens if the bulb burns and opens circuit ? Does 1500V on the anode, with the grid at GND potential, and no cathode current, constitute a hazard ?
There would be an interstage transformer at the grid of the GM-70 ...
Ideas ? / comments ?
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