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" [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
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 [email protected] ======================================