[amsat-bb] Re: Who is using a IC-910 with Maspro Antennas?
tosca005 at umn.edu
tosca005 at umn.edu
Wed Nov 21 08:50:10 PST 2012
Note that Jan is specifically asking about VO-52 (mode UV), *NOT* FO-29
(mode VU). There is a big difference. When the uplink is VHF, the third
harmonic of 145 MHz is 435 MHz so desense is often a problem. I have always
noticed that difficulty with my FT-847 on FO-29 in the absence of external
filtering, but a desense filter (filter out the 435 MHz harmonic from the
145 MHz side of the radio) is very helpful. But on mode UV, the transmitter
is in the 435 MHz band and so interference in the 145 MHz band should be
small. I have always found it extremely easy to operate VO-52 on my FT-847
without any particular extra filtering, unlike FO-29. And it sounds like
Jan likewise was successful in working VO-52 in the past with his (now
So, this leads me to believe that Jan's system does have some problem. I am
not familiar with either the IC-910 or the Maspro antennas, so I can't
diagnose further. Separate bandpass filters on the VHF and UHF sides of the
radio can likely help, but there may be more to the problem than meets the
eye. At least it seems so from my state of ignorance about his specific
73 de W0JT
John P. Toscano
On Nov 21 2012, Dimitry Borzenko wrote:
>Try "Desense" filter.
>More info here - http://www.amsat.org/amsat-new/articles/Mode-J/
>From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
>Behalf Of PE0SAT | Amateur Radio
>Sent: Tuesday, November 20, 2012 8:12 PM
>To: Amsat bb
>Subject: [amsat-bb] Who is using a IC-910 with Maspro Antennas?
>Thanks for reading this message. I have exchanged my FT-847 for an
>IC-910H and now when I try to
>work VO-52 my UHF uplink signal interferes with the VHF downlink. Are
>the any people out there that
>experience the same with this combination?
>I tried with and without pre-amp, RHCP and LHCP but the problems
>doesn't go away :(
>I do know that there can be problems when working FO-29 and a mode-j
>filter can solve this, but I
>never experiences this when working VO-52.
>73 Jan PE0SAT
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