[amsat-bb] Diplexer, Arrow ant, 2 handhelds question

[Jeff Johns]

Speaking of filtering the MIni Circuits BLP-200 as recommended to me by W8LID has made all the difference for me and W4AQT when working the linear birds using a FT-1634. No more desense and crackling and popping in our headphones.

Jeff WE4B

> On Mar 26, 2019, at 12:38 PM, Don KB2YSI <kb2ysi at gmail.com> wrote:
> 
> I will have to try this with my IC7100 to see if it makes a difference.
> 
>> On Tue, Mar 26, 2019, 13:14 Stephen E. Belter <seb at wintek.com> wrote:
>> 
>> Steve,
>> 
>> *If* the problem is 3rd harmonics from the 2 m transmitter, then what you
>> did should have helped.  Adding a 50-ohm terminator might improve the
>> attenuation of the 3rd harmonic.
>> 
>> A more common problem is that the 70 cm receiver can't handle the 2 m
>> transmitted signal because the receiver doesn't attenuate the 2 m signal
>> sufficiently.  (The AGC on the radio hears the 2 m signal, attenuates the
>> whole 70 cm band, and you don't hear the satellite.)  By using the Arrow
>> diplexer as a 2 m band reject filter, you may solve your problem.
>> 
>> For a better explanation see, Tony AA2TX's article here:
>> https://www.amsat.org/a-simple-desense-filter-for-mode-j-satellites/
>> 
>> So try your experiment again, but connect the antenna end of the diplexer
>> to the 70 cm antenna and the 70 cm radio end of the diplexer to your
>> receiver.
>> 
>> 73, Steve N9IP
>> --
>> Steve Belter, seb at wintek.com
>> 
>> 
>> 
>> On 3/26/19, 12:18 PM, "AMSAT-BB on behalf of skristof at etczone.com" <
>> amsat-bb-bounces at amsat.org on behalf of skristof at etczone.com> wrote:
>> 
>>    Today, on the SO-50 pass, I tried using the Arrow diplexer (duplexer?)
>>    to enable full-duplex using two handhelds. As most on this forum know,
>>    if you use two handhelds with the Arrow antenna, the third harmonic of
>>    the 2m uplink will desense the 70cm handheld, so you can't hear
>>    yourself.
>> 
>>    So, I hooked up what is normally the antenna end of the diplexer to the
>>    2m uplink radio and the 2m radio end of the diplexer to the 2m part of
>>    the Arrow antenna. My hope was that this would suppress the third
>>    harmonic of the 2m uplink enough so that it wouldn't desense the 70cm
>>    handheld. The 70cm radio end of the diplexer was left unconnected.
>> 
>>    It didn't seem to work. I made contacts but I still didn't hear myself
>>    on 70cm.
>> 
>>    Just wondering if anyone else has tried this and what results you got.
>> 
>>    Steve AI9IN
>> 
>>    EM79ji
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>> 
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
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> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb