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!
----- 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]
Hi Mark, N8MH
The MGF 14......types are MIL versions (Hi-Rel) of the MGF 13..... and MGF 19..... and so "apparently" the MGF 1402 can be repleced by a MGF 1302 with minor current adjustement for the lowest Noise Figure
By the way the MGF 1402 can be directly replaced by a ATF 26550 or MGF 1412 available at 9,30 Euro's from
http://www.rfmicrowave.it/catalogue.php?lang=eng
Look at the Catalog and then click over GaAsFET and FET
If you contact Franco Rota of the above rfmicrowave company I am sure that he has few MGF 1402 at stock
You can pay it with credit card and get the GaAsFET in a few days by regular post.
73" de
i8CVS Domenico
Domenico,
Thank you very much for your advice and the data sheets. I had compared the two data sheets and could not see why a substitution was a bad idea.
I appreciate the other part numbers and source recommendation, too!
73,
Mark N8MH
At 09:49 PM 5/31/2011 +0200, i8cvs wrote:
----- 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]
Hi Mark, N8MH
The MGF 14......types are MIL versions (Hi-Rel) of the MGF 13..... and MGF 19..... and so "apparently" the MGF 1402 can be repleced by a MGF 1302 with minor current adjustement for the lowest Noise Figure
By the way the MGF 1402 can be directly replaced by a ATF 26550 or MGF 1412 available at 9,30 Euro's from
http://www.rfmicrowave.it/catalogue.php?lang=eng
Look at the Catalog and then click over GaAsFET and FET
If you contact Franco Rota of the above rfmicrowave company I am sure that he has few MGF 1402 at stock
You can pay it with credit card and get the GaAsFET in a few days by regular post.
73" de
i8CVS Domenico
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]
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]
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]
One more update: the relays can be purchased here!
http://radiodan.com/ted_stuff/tohtsu.htm
73,
Mark N8MH
At 09:33 PM 6/1/2011 -0400, 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
Hi Mark, N8MH
I have seen the pictures of your Landwehr 70 cm preamplifier and I know very well the model of coax relays used in it.
They are 50 ohm coax relays Tohtsu CX 120 P for printed circuits and can handle 150 watt pep at 500 MHz with an insertion loss of 0.2 dB and a crosstallk (insulation) of 35 dB with a VSWR of 1,08 at 1 GHz
don't worry about to clean the contacts because they are very large silver contacts and you just need to remove the side cover with your fingers and spry a contact cleaner over it.
I use four of them in my switching four polarizations switcher on a 70 cm crossed yagi as you can read into the AMSAT Journal March/April and May/June 2007
Have fun
73" de
i8CVS Domenico
----- Original Message ----- From: "Mark L. Hammond" [email protected] To: "i8cvs" [email protected]; "Amsat - BBs" [email protected] Cc: "Vince Fiscus, KB7ADL" [email protected]; "K5OE" [email protected] Sent: Thursday, June 02, 2011 3:33 AM Subject: Re: Fixed! Re: Landwehr 70cm preamp device question?
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]
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] ======================================
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 NØJY
AO-51 solid signals in ZL. AOS (0459 UT) about five minutes after it came out of eclipse.
Alan ZL2BX
Thanks, Alan! Keep the reports coming.
73,
Mark N8MH
On Fri, Jun 3, 2011 at 1:16 AM, Alan Cresswell [email protected] wrote:
AO-51 solid signals in ZL. AOS (0459 UT) about five minutes after it came out of eclipse.
Alan ZL2BX
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
Hi Mark,
Well I can finally confirm that AO-51 is loud and clear over ZL in full eclipse. AOS 1435 UTC. Solid signals from the transponder.
Alan ZL2BX
-----Original Message----- From: Mark L. Hammond [mailto:[email protected]] Sent: Friday, 3 June 2011 09:32 To: Alan Cresswell Cc: [email protected] Subject: Re: [amsat-bb] AO-51over ZL
Thanks, Alan! Keep the reports coming.
73,
Mark N8MH
On Fri, Jun 3, 2011 at 1:16 AM, Alan Cresswell [email protected] wrote:
AO-51 solid signals in ZL. AOS (0459 UT) about five minutes after it
came
out of eclipse.
Alan ZL2BX
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
participants (5)
-
Alan Cresswell -
Edward R. Cole -
i8cvs -
Mark L. Hammond -
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