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]