I'd appreciate any info on who repairs Landwehr preamps (VHF and UHF). Resurrecting mine from 1990 and they are both dead. They have what I recall to be the classic symptom of a blown GasFET, when you apply power you get about 30dB of loss.
Jim WD0E jim@coloradosatellite.com
Jim,
Check with Radio Dan:
http://www.radiodan.com/ted_stuff/landwehr.htm
The schematics can be downloaded at the bottom of the page.
73s,
Alan WA4SCA
<-----Original Message----- <From: amsat-bb-bounces@amsat.org <[mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim White <Sent: Thursday, June 05, 2014 10:22 AM <To: AMSAT-BB <Subject: [amsat-bb] (no subject) < <I'd appreciate any info on who repairs Landwehr preamps (VHF <and UHF). <Resurrecting mine from 1990 and they are both dead. They have what I <recall to be the classic symptom of a blown GasFET, when you <apply power <you get about 30dB of loss. < <Jim <WD0E <jim@coloradosatellite.com <_______________________________________________ <Sent via AMSAT-BB@amsat.org. 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 <
Hi Alan, WA4SCA and Jim WD0E
I have inspected the VHF and UHF schematic diagrams at
http://www.radiodan.com/ted_stuff/landwehr.htm
and found that for 435 MHz the input GaAsFET Q1 is a widely well know MGF-1402
For 2 meters VHF the input GaAsFET T5 is a N Channel GaAs-Shotky Gate Tetrode (for example TEXAS S 3030 ) wich is more difficult to find BTW the 2SK571 or the 2SK406 should work equally well
see also:
http://www.google.it/search?hl=it&gbv=2&q=landwehr+preamplifier&...
In any case the Manufacturer of Landwehr was in Sweeden starting about 30 years ago and the owner of the Company was a radio ham active on 432 MHz off the moon.
I have contact him on EME several time but actually I don't remember if he was SM6AKW or SM3CKU and unfortunately both of them do not appears on QRZ.com
It should be nice to investigate onto the american callbook and sent to both a letter.
Have fun
Best 73" de i8CVS Domenico
----- Original Message ----- From: "Alan" wa4sca@gmail.com To: "'Jim White'" jim@coloradosatellite.com; "'AMSAT-BB'" amsat-bb@amsat.org Sent: Thursday, June 05, 2014 5:58 PM Subject: Re: [amsat-bb] (no subject)
Jim,
Check with Radio Dan:
http://www.radiodan.com/ted_stuff/landwehr.htm
The schematics can be downloaded at the bottom of the page.
73s,
Alan WA4SCA
<-----Original Message----- <From: amsat-bb-bounces@amsat.org <[mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim White <Sent: Thursday, June 05, 2014 10:22 AM <To: AMSAT-BB <Subject: [amsat-bb] (no subject) < <I'd appreciate any info on who repairs Landwehr preamps (VHF <and UHF). <Resurrecting mine from 1990 and they are both dead. They have what I <recall to be the classic symptom of a blown GasFET, when you <apply power <you get about 30dB of loss. < <Jim <WD0E <jim@coloradosatellite.com
participants (3)
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Alan -
i8cvs -
Jim White