Yo,
My QTH is the highest point of a ridge, line of sight of several
different installations for paging, police, fire and probably
interstellar communications. Notch filters before or after the preamp
didn't help much on 2M. Taking the preamp out of line helped minimally.
What worked the best was a DCI-145-2H. Cruise to
www.dci.ca/?section=Products&SubSection=Amateur
I placed this between the radio and amplifier and can work weak signal
on 2M when it is available.
I do not own DCI, work for them or benefit from their sales in any way
other than helping me to hear better on 2M.
73 and I remain,
Lew w7ew
On Sun, May 11, 2014 at 12:01 PM, Joe Subich, W4TV <lists@subich.com> wrote:
>
> It depends on whether the preamp is generating the intermod or the
> IC-9100 is generating the intermod. If the intermod is due to mixing
> in the IC-9100's internal preamp, put the notch filter between the
> LNA and IC-9100 so it does not impact the system noise figure.
>
> 73,
>
> ... Joe, W4TV
>
>
>
> On 5/11/2014 2:14 PM, Drax Felton wrote:
>
>> The notch will only be in the receive path since the setup has a mast
>> mounted rx/tx relay too that protects the LNA.
>>
>> -----Original Message-----
>> From: John Lemay [mailto:john@carltonhouse.eclipse.co.uk]
>> Sent: Sunday, May 11, 2014 2:12 PM
>> To: 'Drax Felton'
>> Subject: RE: [TowerTalk] 2m intermod filter placement
>>
>> Drax
>>
>> The right answer will depend on your individual circumstances. However,
>> it's
>> far easier to try it after the preamp, ie next to the rig. If it works,
>> that's just fine. If it doesn't work then you need to try it before the
>> preamp. Doing that will undoubtedly place some loss before the preamp and
>> affect your overall noise figure, which is a good reason for this to be
>> the
>> second choice.
>>
>> Is the notch filter designed to withstand your EME transmit power ?
>>
>> John G4ZTR
>>
>>
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
>> Drax
>> Felton
>> Sent: 11 May 2014 19:00
>> To: towertalk@contesting.com
>> Subject: [TowerTalk] 2m intermod filter placement
>>
>> I recently put up a phased set of four 2m meter antenna for EME to find
>> out
>> that the front end of my IC-9100 is being blasted by pager intermod.
>>
>> I got a notch filter for the frequencies involved from PAR Electronics.
>> Question is now: Where inline is the best place to put the filter?
>>
>>
>>
>> Before or after the mast mounted pre-amp? Or down at the radio end?
>>
>>
>>
>>
>>
>> KB3X
>>
>>
>>
>> _______________________________________________
>>
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