[amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink

[Jim Jerzycke]

Since I use a very good 2 Meter bandpass filter on my 2 Meter output, I 
use the diplexer AT the antenna, ahead of the preamp.

Jim  KQ6EA


On 01/20/2014 03:41 AM, Greg D wrote:
> I know this has been answered before, but I forget.  Given one 
> Diplexer, is it better to put it on the Tx side to limit the 3rd 
> harmionic going out, or better on the Rx side to limit the VHF 
> fundamental coming in?  Tony's diagram shows the later; I would have 
> thought the former would be more effective (hitting the problem at its 
> source).
>
> Greg  KO6TH
>
>
> Jim Jerzycke wrote:
>> Yep, been using one of those for years!
>>
>> I have a Sinclair Labs unit that provides 100dB rejection outside of 
>> the 2 Meter band.
>>
>> Jim  KQ6EA
>>
>>
>> On 01/19/2014 07:32 PM, w4tas wrote:
>>> I would also suggest a low pass filter on the two meter transmitter.
>>> A diplexer will work well for this also.
>>> This will reduce the third harmonic which is causing your problem.
>>>
>>> Good luck,
>>>
>>>
>>>
>>>
>>> -----Original Message----- From: Jim Jerzycke
>>> Sent: Sunday, January 19, 2014 2:09 PM
>>> To: amsat-bb at amsat.org
>>> Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
>>>
>>> Buy a diplexer, and connect it as shown in the linked article:
>>>
>>>
>>> http://www.amsat.org/amsat-new/articles/Mode-J/
>>>
>>> I also tilt both of my Yagis so they're 45* to the boom, which makes
>>> them 90* to each other.
>>>
>>> Yes, I lose some signal on terrestrial use, but ti helped cut the
>>> coupling, and desense, down quite a bit.
>>>
>>> 73, Jim  KQ6EA
>>>
>>> On 01/19/2014 06:56 PM, Gabriel - EA6VQ wrote:
>>>> Hi all,
>>>>
>>>> I have a coupling problem in my station when trying to work FO-29.  
>>>> My 2m
>>>> signal is completely blocking the 435 MHz downlink, and so I can't 
>>>> hear my
>>>> signal off the satellite. I guess it must be something related to the
>>>> distance between the two yagis. (I use the terrestrial horizontal 
>>>> yagis you
>>>> can see at http://www.dxmaps.com/jm19hn.html ). With mode-B 
>>>> satellites there
>>>> is no problem.  I have tried it with two different 435 receivers, 
>>>> and it's
>>>> exactly the same.
>>>>
>>>> Anyone has had this problem o have an idea of the possible reason?  
>>>> And what
>>>> is more important, of some way to solve it?
>>>>
>>>> Thanks for any possible help.
>>>>
>>>> 73. Gabriel - EA6VQ
>>>> _________________________________________________________
>>>> Web-Site: HTTP://www.dxmaps.com
>>>> VQLog 3.1 (build 78): HTTP://www.vqlog.com
>>>> _________________________________________________________
>>>>
>>>>
>>>> _______________________________________________
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>>>
>>> _______________________________________________
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>>
>> _______________________________________________
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>
>