Hi everybody:
I'm looking for the schematic diagram of a preamp protector against TX. I know the impressive quarter wave design with square brass stock and clamping diodes for 432 EME which Domenico, I8CVS, described I don't remember where. Rather I'm looking for something much compact as I would like to use from VHF to above. I mean one of these small boxes (RF diode clippers???) I see sometimes on commercial pages which promises withstand 25W for a short period I'll appreciate any comment about the issue. Thanks in advance.
EA4DUT, Angel IN80FF
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----- Original Message ----- From: "Angel Peláez, EA4DUT" [email protected] To: [email protected] Sent: Friday, September 15, 2006 4:10 PM Subject: [amsat-bb] Preamp protection
Hi everybody:
I'm looking for the schematic diagram of a preamp protector against TX. I know the impressive quarter wave design with square brass stock and clamping diodes for 432 EME which Domenico, I8CVS, described I don't remember where.
Hi Angel, EA4DUT
Just to remember this is the link
http://www.k3pgp.org/432filter.htm
Rather I'm looking for something much compact as I would like to use from VHF to above. I mean one of these small boxes (RF diode clippers???) I see sometimes on commercial pages which promises withstand 25W for a short period I'll appreciate any comment about the issue.
I understand but the above filter/protection withstand much more and tested with 400 watt in to the input less than 80 mW was measured at the output.
While dimensions are for 70 cm they can be scaled in to any VHF/UHF/SHF band adding filtering to protection and it is very inexpensive and reliable.
Thanks in advance.
EA4DUT, Angel IN80FF
73" de
i8CVS Domenico
Hi Angel,
BTW, I wondered about the same thing a few months ago and I found as "Final Solution" the intended (by Domenico, i8CVS) filter. However, I had 1-2 ideas and I believe that you can do it also by using 2x "Quarter Wave" (Lambda/4) coaxial pieces and between of them the two antiparallel diodes. The coaxial pieces is possible to have any form, so the circuit can be compact enough but I've no idea about the max. isolation of this combination in dB. In other words I can't say under how much TX power remains safe the pre-amp. Another approach is that, by replacing the 2 diodes with just a PIN diode. With a sensitive RF-sniffer circuit, you can put a Bias-voltage onto PIN-diode when you have a faulty PTTand thus, the input-output of 2x "Quarter Wave line" produced very high Z, protecting this way your pre-amp.
Good luck (without... smoke on your pre-amp !)
73, Mak SV1BSX
----- Original Message ----- From: "Angel Peláez, EA4DUT" [email protected] To: [email protected] Sent: Friday, September 15, 2006 5:10 PM Subject: [amsat-bb] Preamp protection
Hi everybody:
I'm looking for the schematic diagram of a preamp protector against TX. I know the impressive quarter wave design with square brass stock and clamping diodes for 432 EME which Domenico, I8CVS, described I don't remember where. Rather I'm looking for something much compact as I would like to use from VHF to above. I mean one of these small boxes (RF diode clippers???) I see sometimes on commercial pages which promises withstand 25W for a short period I'll appreciate any comment about the issue. Thanks in advance.
EA4DUT, Angel IN80FF
______________________________________________ LLama Gratis a cualquier PC del Mundo. Llamadas a fijos y móviles desde 1 céntimo por minuto. http://es.voice.yahoo.com _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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participants (3)
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Angel Peláez, EA4DUT -
i8cvs -
SV1BSX