In case anyone is interested in further information.
https://www.mobilewirelesstesting.com/video-understanding-pim/?utm_source=email&utm_medium=email&utm_campaign=mntnews1119&sap-outbound-id=B66B91E0ADAB9E93B52837C03FA1CB29FD26682B&utm_source=SAPHybris&utm_medium=email&utm_campaign=1398&utm_term=20191121_NA_MNT_NovNews_PIM___Title&utm_content=EN
https://www.mobilewirelesstesting.com/understanding-pim/?utm_source=email&utm_medium=email&utm_campaign=mntnews1119&sap-outbound-id=B66B91E0ADAB9E93B52837C03FA1CB29FD26682B&utm_source=SAPHybris&utm_medium=email&utm_campaign=1398&utm_term=20191121_NA_MNT_NovNews_PIM___Title&utm_content=EN
tnx
Mike / W5JR
Alpharetta GA
> On Nov 21, 2019, at 6:00 AM, Martin Sole <hs0zed@gmail.com> wrote:
>
> Dear Jim and Mike,
>
> Thanks very much for the prompt replies.
>
> Jim, I think the chokes are either from your latest work using big 31 rings
> or from the design by GM3SEK using multiple big beads and with I believe at
> least two such chokes in series. That is for each of the feeds to the
> antennas. The chokes are placed just slightly before the Array solution
> balun, again one at each feed point. I will review your other document as
> well, I can see it references issues similar to that which I have observed
> first hand. Yes the harmonic DOES have a growl to it!
>
> The cable is predominantly 1/2" heliax of various manufacturer, based on what
> is available in country but all used in pro installations so generally decent
> stuff. There is some RG214 and some may have a foil. I do know that some of
> the stubs and their associated coupling cables I prepared are made with an
> RG214 that has 2 braids plus a foil and a dielectric that has 0.8v.f.
>
> If foil and braid coax is used what is the issue?
>
> Is there a PIM risk between the braid and the foil?
>
> I am familiar with PIM having seen it first hand at VHF though it was always
> true intermod, being two incident signals creating a third order product.
> Though in those cases we never considered or cared about harmonics, for other
> reasons, I can agree that the non linear device should indeed produce all
> possible products including harmonics of a single source.
>
> Regards es tnx
> Martin, HS0ZED
>
>
>
>> On 21/11/2019 12:40, Mike - W5JR wrote:
>> If any of the “RG214” is in fact a shield over foil braid, replace it with
>> real RG214. As Jim mentions, passive intermod (PIM) usually rears its ugly
>> head after installation of all the cool stuff. You will want to confirm that
>> all of the components, radios, amplifiers, filters, feedlines, towers, guy
>> systems, are *bonded* together to further reduce the possibility of PIM.
>>
>> PIM will be the biggest hurdle in making any multi transmitter situation
>> play nice. Often the PIM generator is external to your feedline or antenna.
>> It’s the “killjoy” of many a Field Day setup over here.
>>
>>
>> tnx
>> Mike / W5JR
>> Alpharetta GA
>
>> On 21/11/2019 11:52, Jim Brown wrote:
>> Hi Martin,
>>
>> here's an "overview" talk that I've done at Visalia last spring and for a
>> couple of clubs, including NCCC, this fall.
>>
>> http://k9yc.com/Multi-Station.pdf
>>
>> Among other things, check out the chokes in my newest Cookbook, which are
>> significantly better and more repeatable designs than what I was able to do
>> 10 years earlier.
>>
>> Also, consider passive intermod.
>>
>> 73, Jim K9YC
>>
>>
>>> On 11/20/2019 8:22 PM, Martin Sole wrote:
>>> Hi,
>>>
>>> This is about a two radio inter-station interference problem. A bit
>>> different perhaps but still RFI of a sort
>>> Looking for some input to help me understand a bit better what is happening
>>> and maybe correct some errors in my thinking.
>>
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