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| To: | [email protected] |
|---|---|
| Subject: | Re: LF: Razor blade RX |
| From: | [email protected] |
| Date: | Tue, 06 Jan 2009 17:40:05 -0500 |
| In-reply-to: | <00b701c97028$b2fd5780$0301a8c0@mal769a60aa920> |
| References: | <00b701c97028$b2fd5780$0301a8c0@mal769a60aa920> |
| Reply-to: | [email protected] |
| Sender: | [email protected] |
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From what I remember, many modern blades will not work very well due to being alloys resistant to "rusting". The blade needs to develop a good coating of corrosion products and it seems not to matter whether this is achieved by natural oxidation by exposure to atmosphere or by encouragement by rubbing with salt. I believe the "fence wire" was used as antenna and together with an"earth/ground" achieved an aperiodic circuit. The audio was produced via a telephone earpiece. More sophisticated circuits were built using wound inductances and variable capacitors - either home-brew or purloined/traded. Otherwise "tuning" of the BBC was achieved by listenig at the appropriate time of day for suitable propogation. It is worth remembering that the guys who were doing this came from a generation who were more than used to creating radio in such simple ways and often driven to "clandestine" methods by restrictions placed on them at boarding schools. I can certainly remember constructing such a "Xtal" set at boarding school in 1954/55 using a coil from REPANCO of Coventry, a "postage stamp" trimmer, an unbranded "xtal diode" (early germanium point contact) and an earpiece which was one half of an ex-military headset. The rx was built into a very small wooden box little larger than a matchbox and after "lights-out" the antenna/earth connections were achieved by connection to bed springs and the hot water pipe that ran the length of the dormitory.
It would be interesting to hear the experiences of other "old fogeys".
Incidentally, eperiments included substituting a baked bean can for the earpiece diaphragm in an attempt to let more of my friends listen to the BBC Light Programme! And to think that from such are radio amateurs born! 73 de Pat G4GVW From: mal hamilton <[email protected]> To: rsgb <[email protected]> Sent: Tue, 6 Jan 2009 18:00 Subject: LF: Razor blade RX Since I mentioned a Razor blade and fence wire RX a
while back I have had several requests for a circuit. To give others the
opportunity to submit a cct I will await replies. This method was used
successfully at Coldiz and other POW camps to receive BBC
broadcasts.
Let us know how you would approach the subject.
This is applicable to MF/LF since the broadcasts at the time were receicved on
these bands.
Build one and have a QSO using this RX
g3kev
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