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Medium wave pre selector
Apart from Ham radio, I like DXing on many other bands, including LF and MW.
I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) Rgds Richard SO5GB |
"Richard" wrote in message ... Apart from Ham radio, I like DXing on many other bands, including LF and MW. I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) Rgds Richard SO5GB =============================== Download in a few seconds program SELECT_1 from website below and run immediately. Also includes tuning coil design. Ideal for MW. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
"Richard" wrote in message ... Apart from Ham radio, I like DXing on many other bands, including LF and MW. I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) Rgds Richard SO5GB =============================== Download in a few seconds program SELECT_1 from website below and run immediately. Also includes tuning coil design. Ideal for MW. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Something like this?
http://www.ac6v.com/components.htm Just build the first circuit without the remote. jw K9RZZ |
Something like this?
http://www.ac6v.com/components.htm Just build the first circuit without the remote. jw K9RZZ |
Here's a beauty I use:
http://www3.telus.net/small_business...BJ6-RF-Amp.png -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Here's a beauty I use:
http://www3.telus.net/small_business...BJ6-RF-Amp.png -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
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On Sat, 22 May 2004 00:46:39 +0000 (UTC), in
rec.radio.amateur.homebrew you wrote: "Richard" wrote in message ... Apart from Ham radio, I like DXing on many other bands, including LF and MW. I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) Download in a few seconds program SELECT_1 from website below and run immediately. Also includes tuning coil design. Ideal for MW. ....... well, it is so nice to inform about my own site, although it has nothing to do with the request, neither does your reply A quick calculation for a tuned circuit gave the results of a single circuitfilter covering 500-1793kHz. Not quite as sharp as requested, the coil turn calculation might have been right, but what does it help? sri, OM 73 Jan-Martin http://www.noding.com/la8ak/12345/n13.htm |
On Sat, 22 May 2004 00:46:39 +0000 (UTC), in
rec.radio.amateur.homebrew you wrote: "Richard" wrote in message ... Apart from Ham radio, I like DXing on many other bands, including LF and MW. I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) Download in a few seconds program SELECT_1 from website below and run immediately. Also includes tuning coil design. Ideal for MW. ....... well, it is so nice to inform about my own site, although it has nothing to do with the request, neither does your reply A quick calculation for a tuned circuit gave the results of a single circuitfilter covering 500-1793kHz. Not quite as sharp as requested, the coil turn calculation might have been right, but what does it help? sri, OM 73 Jan-Martin http://www.noding.com/la8ak/12345/n13.htm |
On Fri, 21 May 2004 21:52:06 +0200, "Richard"
wrote: I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) I have used for LF a parallel resonant circuit followed by a (Darlington) emitter follower driving the 50 ohm line to the receiver. Assuming hFE=100 for each transistor, the resonant circuit loading is about 500 kohm, thus the loading is quite small. Since the antenna was short compared to the wavelength and thus highly capacitive, a small 10-100 pF capacitor was used to connect to the hot side of the resonant circuit. Although the voltage gain is only 1, it works surprisingly well due to the large (natural and artificial) field strengths in the LF and lower MF bands. When using some processor controlled receiver, it is a good idea to move the preselector (and hence the antenna connection) as far as possible from the receiver and connect them with a shielded cable, to prevent the receiver processor radiation from entering the high impedance antenna connection. A 1-2 m separation helps a lot, without making it too uncomfortable to operate. Paul OH3LWR |
On Fri, 21 May 2004 21:52:06 +0200, "Richard"
wrote: I am looking for a circuit diagam for a MW pre selector, anything would be of interest, bit if someohw has one of thoese super dooper ones that can focus donw to a few khz that wold be even better, (like the palomar MW pre selector) I have used for LF a parallel resonant circuit followed by a (Darlington) emitter follower driving the 50 ohm line to the receiver. Assuming hFE=100 for each transistor, the resonant circuit loading is about 500 kohm, thus the loading is quite small. Since the antenna was short compared to the wavelength and thus highly capacitive, a small 10-100 pF capacitor was used to connect to the hot side of the resonant circuit. Although the voltage gain is only 1, it works surprisingly well due to the large (natural and artificial) field strengths in the LF and lower MF bands. When using some processor controlled receiver, it is a good idea to move the preselector (and hence the antenna connection) as far as possible from the receiver and connect them with a shielded cable, to prevent the receiver processor radiation from entering the high impedance antenna connection. A 1-2 m separation helps a lot, without making it too uncomfortable to operate. Paul OH3LWR |
I am looking for a circuit diagam for a MW pre selector, anything would be of interest A Cohn filter covering 1.75-7.2kHz, is shown on http://home.online.no/~la8ak/c11.htm some Cohn filters have been published and turned out to be extremely difficult to copy, but LA7MI claims this is quite easy to make. Perhaps somebody could scaLe the values down to the mediumwave band? I've received some more requests for such construction, so I am not worried whether this writer needed a simple filter or not, it is a lot of demands for useful solutions 73 jm |
I am looking for a circuit diagam for a MW pre selector, anything would be of interest A Cohn filter covering 1.75-7.2kHz, is shown on http://home.online.no/~la8ak/c11.htm some Cohn filters have been published and turned out to be extremely difficult to copy, but LA7MI claims this is quite easy to make. Perhaps somebody could scaLe the values down to the mediumwave band? I've received some more requests for such construction, so I am not worried whether this writer needed a simple filter or not, it is a lot of demands for useful solutions 73 jm |
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