I was not aware of these little pcb coax relays. I think one could make a neat CP reversal switch using them on a pcb that could handle normal satellite RF levels (<100w) at a reasonable cost. Much better than what is used on KLM CP antennas.
One could make switching preamps using two of them with any preamp ------------------------------------------------------------------------ I use a couple CX-600NL in my 2m-eme system for polarity switching, but do not have enough isolation (48-dB) for preamps when transmitting 1000w (60dBm). So I use two Narda relays with 80-dB isolation. I am going to use one of the CX-600NL for 6m-eme switching 1100w where isolation is 60-dB. 73, Ed - KL7uW At 05:33 PM 6/1/2011, Mark L. Hammond wrote: >Hello Domenico I8CVS, > >I did take pictures while I had the cover off :) You can see and >download them here: > >https://sites.google.com/site/marklhammond/hamradio > >Indeed, they are labeled "COAXIAL RELAYS" as you suspected. > >You can also see the "little white button" on the relays that I >mentioned previously. > >73! > >Mark N8MH > >At 02:42 AM 6/2/2011 +0200, i8cvs wrote: > >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" <marklhamm...@gmail.com> > >To: "Amsat - BBs" <amsat-bb@amsat.org> > >Cc: "i8cvs" <domenico.i8...@tin.it>; "Vince Fiscus, KB7ADL" > ><vlfis...@mcn.net>; "K5OE" <k...@aol.com> > >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" <marklhamm...@gmail.com> > >> >>To: "Amsat - BBs" <amsat-bb@amsat.org> > >> >>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 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 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-testing*, 3400-? DUBUS Magazine USA Rep dubus...@hotmail.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
