Uploaded January 2026 | Updated September 2026, 3 weeks ago
Let's address a problem for crystal radio builders, the disappearance of classic germanium detector diodes such as the 1N34A and D9K. Crystal radios and other applications depend on diode performance at microamp currents, where forward voltage drop (Vf) matters. We look over a list of over 20 additional candidate diodes from Western, Soviet-era, Japanese, British, and German manufacturers that appear promising based on available specifications. These are untested (by me). We also look at the often-suggested BFP740 transistor base-emitter junction as a detector, including measured Vf values and practical tradeoffs. This video is for serious DIYers, crystal radio enthusiasts, and experimenters who want accurate, responsible information rather than speculation, and I invite viewers with real test data to contribute their results for the benefit of the community.
I'm in a quandary. I've found a huge number of POTENTIAL crystal radio diodes based on their specs. It will take years for me to find them and test them all. In the mean time, these could possibly be used by builders. So I have decided to release my list with the warning that these are UNTESTED by me for crystal radio use. There's a good chance they will work, but I have not proven it to myself, so I am reluctant to make any statement about them.
Known Diodes
1N34A
D9K
1N60
UNtested / Unverified* (by me) Classified By Region Of Origin
Western / JEDEC / Pro Electron
1N270 – Alloy germanium, slightly higher robustness
OA90 – Extremely close to OA91, slightly lower Vf
OA91 / OA91A – Common European detector diode
OA95 – Slightly higher Vf
OA47 – Older Mullard company detector, very good at LF/MW
AA119 – High-quality Mullard germanium detector
AA112 / AA113 – Similar behavior, lower capacitance
*Warning: I have not tested these, buy & use at your own risk.
Soviet / Eastern Bloc Germanium Detector Diodes
Д9К (D9K) – Very close to 1N34A
Д9Б (D9B) – Slightly different leakage, still excellent
Д18 (D18) – Lower capacitance variant
Д311 / Д312 – Older Soviet detector types
ГД507 (GD507) – Detector-class germanium
*Warning: I have not tested these, buy & use at your own risk.
Japanese Germanium Detector Diodes
1S5 / 1S7 – Common AM detector diodes
1S34 – Equivalent to 1N34A
1S188 / 1S1555 – Low-capacitance germanium RF detectors
*Warning: I have not tested these, buy & use at your own risk.
Less Common but electrically similar germanium detectors:
GEX34 – Early germanium experimental detector
CV7001 / CV7003 – British military detector diodes
SD101 – German detector diode
*Warning: I have not tested these, buy & use at your own risk.
RELATED VIDEOS (including this one):
Disclaimer: This information is presented as entertainment only on an "as is" basis and any use the viewer makes of it is solely up to them, and it is their responsibility to determine if the information remains current and if it is applicable to their situation. The viewer is responsible for any and all safety involving this. Viewing this video is the viewer's agreement to these terms and conditions. If you do not agree, stop now.
#CrystalRadio #GermaniumDiodes #ElectronicsDIY #RadioExperimentation
Let's address a problem for crystal radio builders, the disappearance of classic germanium detector diodes such as the 1N34A and D9K. Crystal radios and other applications depend on diode performance at microamp currents, where forward voltage drop (Vf) matters. We look over a list of over 20 additional candidate diodes from Western, Soviet-era, Japanese, British, and German manufacturers that appear promising based on available specifications. These are untested (by me). We also look at the often-suggested BFP740 transistor base-emitter junction as a detector, including measured Vf values and practical tradeoffs. This video is for serious DIYers, crystal radio enthusiasts, and experimenters who want accurate, responsible information rather than speculation, and I invite viewers with real test data to contribute their results for the benefit of the community.
I'm in a quandary. I've found a huge number of POTENTIAL crystal radio diodes based on their specs. It will take years for me to find them and test them all. In the mean time, these could possibly be used by builders. So I have decided to release my list with the warning that these are UNTESTED by me for crystal radio use. There's a good chance they will work, but I have not proven it to myself, so I am reluctant to make any statement about them.
Known Diodes
1N34A
D9K
1N60
UNtested / Unverified* (by me) Classified By Region Of Origin
Western / JEDEC / Pro Electron
1N270 – Alloy germanium, slightly higher robustness
OA90 – Extremely close to OA91, slightly lower Vf
OA91 / OA91A – Common European detector diode
OA95 – Slightly higher Vf
OA47 – Older Mullard company detector, very good at LF/MW
AA119 – High-quality Mullard germanium detector
AA112 / AA113 – Similar behavior, lower capacitance
*Warning: I have not tested these, buy & use at your own risk.
Soviet / Eastern Bloc Germanium Detector Diodes
Д9К (D9K) – Very close to 1N34A
Д9Б (D9B) – Slightly different leakage, still excellent
Д18 (D18) – Lower capacitance variant
Д311 / Д312 – Older Soviet detector types
ГД507 (GD507) – Detector-class germanium
*Warning: I have not tested these, buy & use at your own risk.
Japanese Germanium Detector Diodes
1S5 / 1S7 – Common AM detector diodes
1S34 – Equivalent to 1N34A
1S188 / 1S1555 – Low-capacitance germanium RF detectors
*Warning: I have not tested these, buy & use at your own risk.
Less Common but electrically similar germanium detectors:
GEX34 – Early germanium experimental detector
CV7001 / CV7003 – British military detector diodes
SD101 – German detector diode
*Warning: I have not tested these, buy & use at your own risk.
RELATED VIDEOS (including this one):
Disclaimer: This information is presented as entertainment only on an "as is" basis and any use the viewer makes of it is solely up to them, and it is their responsibility to determine if the information remains current and if it is applicable to their situation. The viewer is responsible for any and all safety involving this. Viewing this video is the viewer's agreement to these terms and conditions. If you do not agree, stop now.
#CrystalRadio #GermaniumDiodes #ElectronicsDIY #RadioExperimentation
