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PA3AKK > QRP 29.04.08 16:25l 52 Lines 2246 Bytes #999 (0) @ WW
BID : 53539_PI8CDR
Read: GUEST
Subj: Re: ZL1ABS: 455kHz Product detector wanted
Path: IZ3LSV<IQ0LT<IK2XDE<DB0RES<DK0WUE<7M3TJZ<IK6PYS<ON0BEL<PI8CDR
Sent: 080429/1522Z @:PI8CDR.#DRE.NLD.EU #:53539 [Beilen] $:53539_PI8CDR
From: PA3AKK@PI8CDR.#DRE.NLD.EU
To : QRP@WW
>Wanted
>
>Some ideas for a 455 kHz product detector for SSB/CW in a homebrew
>receiver.
What about this?
This detector is often used in 80 m fox hunting receivers.
+ 6 V
|
|
+-------------------------+---------------------+
| |
| ---
| input 0 V | |
--- | | | | 1 MOhm
| | 455 kHz | | | |
| | 10 kOhm MF signal | | ---
| | | | |
--- | - diode |
| | ^ |
| 10 pF | | | 100 nF audio
+-------------------------+--||---+-----+--|<---+--||--+----+-- output
| 1 MOhm | diode | | |
| _______ | | | |
+--|_______|--+ | --- --- ---
| | 455 kHz | --- --- | |
| | ceramic | 22 nF| 22 nF| | |10 kOhm
c \ | filter | | | | |
\| c | | | | | | | ---
BC547 |---------+---| | |---+ | | |
e /<| | | | | | |
/ | | | |
| | | | |
| | | | |
+-------------------+-------------+-------------+------+----+
|
|
0 V
To select the 455 kHz MF signal two or more ceramic filters in serie with a 47
pF capacitor in between.
73, Wim
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