Hi Mark, N8MH and All guys on the list. I am very happy that you solved the problem on your preamplifier and since you took the cover off I would like to know if the relays are or not "COAXIAL RELAYS" or just non constant impedance relays for AC or DC applications.
Can you take a picture on the inside of preamplifier and send it to me by email ? I remember that the owner of Landwehr was a 432 MHz EME'r in the early 1973 and I worked him off the moon but actually I don't remember his call letter from Sweden. I believe that he dismitted the production of the above preamplifiers many years ago. Tanks 73" de i8CVS Domenico ----- Original Message ----- From: "Mark L. Hammond" <[email protected]> To: "Amsat - BBs" <[email protected]> Cc: "i8cvs" <[email protected]>; "Vince Fiscus, KB7ADL" <[email protected]>; "K5OE" <[email protected]> Sent: Thursday, June 02, 2011 1:44 AM Subject: Fixed! Re: Landwehr 70cm preamp device question? > Hello All, > > You gotta love a happy ending ;) > > Thanks to I8CVS, Domenico; Vince, KB7ADL; and Jerry, K5OE for the advice and coaching with troubleshooting my Landwehr 70 cm preamp. > > I took the cover off and applied 12V, and the two relays closed----or did they?!? > > One side looked good, while the other side didn't quite push the "little white button" enough to make the contacts meet. It was stuck--just a gentle push with the finger, and I could tell it had become "unstuck." Inserted back in line, and bingo! It's working just fine. > > I have resisted my urges to spray something down in there...figure I can unstick it the same way another time, should it happen. Looks like the preamp was made in 1990, based on the dates of the relays. > > What I was seeing seemed like it might be a relay issue on one side (could hear a rise in noise, so the relay at the output side (rig) was working--but the relay on the input side (antenna) wasn't. So, when powered, the input relay didn't switch over correctly--what I was seeing now makes sense! > > Anyhow, it wasn't the GaAsFET after all. > > Thanks again for the help, guys. > > 73, > > Mark N8MH > > > >>----- Original Message ----- > >>From: "Mark L. Hammond" <[email protected]> > >>To: "Amsat - BBs" <[email protected]> > >>Sent: Tuesday, May 31, 2011 8:00 PM > >>Subject: [amsat-bb] Landwehr 70cm preamp device question? > >> > >>> Hello All, > >>> > >>> I have an old Landwehr preamp that apparently uses the MGF1402 device > >>> (does that sound right?). It's not working so I presume it's the > >>> GaAsFET. > >>> > >>> Can the MGF1302 be substituted for the original MGF1402? Or can > >>> anybody recommend another device for the 70 cm Landwehr? > >>> > >>> I need to do something... > >>> > >>> Thanks in advance! > >>> > >>> -- > >>> Mark L. Hammond [N8MH] > _______________________________________________ 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
