Those Landwehrs are great preamps. I had an issue similar to Mark's, except it was the transmit side of the Tohtsu relay that had the problem. I could receive fine but had high SWR during TX. Unlike Mark, I did risk a shot of spray, which didn't cure the problem. But then ran a sheet of paper between the contacts and it has worked fine ever since.

73, Bill NZ5N

Subject: [amsat-bb] Re: Fixed! Re: Landwehr 70cm preamp device To: amsat-bb@amsat.org Message-ID:     1020722076.1625425.1307043809981.JavaMail.root@sz0063a.emeryville.ca.mail.comcast.net     Content-Type: text/plain; charset=utf-8

FYI, parts for the Landwehr pre-amps

Ted at Radio DAN still?carries?replacement Mitsubishi MGF1402 GaAsFET (discontinued)

http://www.radiodan.com/ted_stuff/landwehr.htm

RF Parts lists the Mitsubishi MGF series

MGF1402 - was listed as $18.95 in 2007, currently (2011) you need to Call for Price. http://www.rfparts.com/transistors_2SKand3SK.html#bf

Check with K0KN ...?from an earlier AMSAT-BB posting -- he may have?extra !

http://www.amsat.org/amsat/archive/amsat-bb/200701/msg00021.html

PC Electronics?carried the part in 2007, but they may have sold?their remaining stock.

http://www.hamtv.com/specials.html

GH Engineering (UK)

http://www.ghengineering.co.uk/prices.htm#Mitsubishi

Greg

w9gb

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Date: Thu, 2 Jun 2011 08:59:54 -0500 (CDT) From: n0jy Subject: [amsat-bb] Re: Fixed! Re: Landwehr 70cm preamp device ????????question? To: "Mark L. Hammond" Cc: K5OE

I'm glad you shared this all here Mark, I have a 2M Landwehr that's been cranking along since 1993 or so, I've never looked inside but this thread is something I'll keep in case it gets flaky on me.

73, Jerry N0JY