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QSLs from Yugoslavia
YU1OCQYU2RBZYU2RVYYU3CWXYU3DCDYU4FTUYU5CEF_______________________________
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Remembering OM Joe - VU2JA
My memories go back to a day in the year 1976 when OM Ramesh - VU2NRS and I had an eyeball QSO with OM Joe - VU2JA at his shack on # 20, Union Street, Bangalore.It was in an imposing building with a...
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Crystal Radio Circuits - Alternative Concepts
The most commonly used circuit is parallel-tuned.Parallel-tuned Crystal RadioIt works quite well with a germanium diode series-feeding a pair of sensitive DLR No.5 I.T.B.A.5 S balanced-armature...
View ArticleRemembering radio pioneer J.C.Bose
Here's a comprehensive article on radio pioneer J.C.Bose.J.C. Bose: 60 GHz in the 1890sInteresting read._______________________________
View ArticleFirst satellite QSO
My first satellite QSO was with my good friend OM Bindu - VU2IR.It was around 6.00pm, one evening in the early 1990s, when Bindu and I were chewing the rag on 2m and he excused himself to work through...
View ArticleSpeaker vibration/distortion
A Radio Cassette Recorder was received for repair.The problem: Speaker vibration/distortion within days of its purchase in another city.On opening the set, a cockroach was found perched on the back of...
View ArticleInjection moulding machine problem
It was a crisis call for a table-top injection moulding machine. Clear acrylic meter faces were being moulded and the output quality had deteriorated overnight.The controls were fairly simple, the key...
View ArticleYaesu FT-747GX - PTH problems
A batch of Yaesu FT-747GX transceivers, produced in the 1990s, is plagued with PTH issues.They show up as intermittent problems in receive and transmit and finally lead to total failure.The faulty...
View ArticleYaesu FT-747GX / FT-757GX - failure to power up
Every Yaesu FT-747GX / FT-757GX user would have been flummoxed by the rig refusing to power up only to discover later that the MOX button had been left actuated.It's a safety interlock to prevent the...
View ArticleDrake TR-4C - receive problem
The old workhorse seldom gave problems on transmit.A frequent receive problem was the receiver going dead on switching back to receive from transmit.The problem was solved by replacing custom C145 (4...
View ArticleLightning jolt
It was a typical summer afternoon in the year 1977.I was working CW on 40m - my homebrew EL84 rig feeding a straight dipole antenna with telephone drop wire as feeder.Meanwhile the sky became overcast...
View ArticleRugged 807 & 1625 tubes
The good old 807 and 1625 tubes can take a real beating.One night decades ago, when I was working DX on CW with the shack lights off, the room suddenly lit up. The cathode-keyed 807 final was white...
View ArticleSome thoughts on shack earthing
The main purpose of mains-supply-earthing (third pin) in the shack is to blow the fuse in the event of a live-chassis fault.Protection against static build-up / lightning strike is another matter...
View ArticleMotor problem
It was just another day at the plant.A colleague from the neighbouring department called to say he had a problem.A replacement three phase induction motor, drawn from the stores and wired, just refused...
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Some thoughts on UHF Crystal Radios
Diode capacitanceLow capacitance diodes are a must for UHF crystal radios.It follows that they are to be so wired that the capacitance between their leads is kept to a minimum.This does not imply that...
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Ideal detector for a Shunt-fed Crystal Radio
A diode with a forward voltage drop as low as 0.25 V may be configured by interconnecting the base and emitter of a Germanium transistor.Basic Shunt-fed Crystal RadioIt's an ideal detector for a...
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Crystal Radio / Piezo Earpiece Interfacing
Here's how to interface a piezo earpiece with a crystal radio.Parallel-tuned, series-fed radio:The earpiece is interfaced through a 33 kΩ shunt resistor. The resistor provides a path for thedetector...
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Crystal Radio Antennas
A medium wave broadcast station antenna system generally comprises a ¼ λ vertical elementand earth.It would not be wrong to infer that such an antenna would be ideal for a crystal radio.Crystal Radio...
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Handy Crystal Radio Antenna
In a ham shack, either half of a 40m inverted ' V ' would come in quite handy as a usable crystalradio antenna element.Handy Crystal Radio AntennaHowever, a suitable loading coil would be required to...
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