[amsat-bb] Re: Fixed! Re: Landwehr 70cm preamp device question?

[Mark L. Hammond]

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" <marklhammond at gmail.com>
>>To: "Amsat - BBs" <amsat-bb at amsat.org>
>>Cc: "i8cvs" <domenico.i8cvs at tin.it>; "Vince Fiscus, KB7ADL"
>><vlfiscus at mcn.net>; "K5OE" <k5oe at 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" <marklhammond at gmail.com>
>>> >>To: "Amsat - BBs" <amsat-bb at 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]
>>>
>
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