DAS - Distributed Antenna systems used in major airport/commercial to
redistribute cellular service
PIM - Passive Intermodulation, usually caused by the rusty(ferrous) connection
that will cause IM products as a result. Usually found in poorly
tightened/crimped connectors and can be caused by an external source outside
the coaxial cables.
Your 2nd harmonic may in fact be caused by a rusty connection somewhere that is
excited with higher power levels. Does it occur no matter what power levels ?
Or just high power levels ?
Stephanie WX3K
> On Aug 8, 2021, at 3:34 PM, Pete Smith N4ZR <pete.n4zr@gmail.com> wrote:
>
>
> PIM? Googled that one without success. Ditto DAS. I agree with your
> diagnostic approach, though
>
> 73, Pete N4ZR
> Check out the new Reverse Beacon Network
> web server at <http://beta.reversebeacon.net>.
> For spots, please use your favorite
> "retail" DX cluster.
> On 8/8/2021 3:28 PM, Stephanie WX3K via RFI wrote:
>> Difficult to use something that selective on HF.
>>
>> I do a lot of PIM troubleshooting on DAS and the BEST method i find is
>> tapping connections/hardware with a rubber mallet while the systems is
>> active. You could remotely watch your secondary RX using remote desktop on
>> your cell
>>
>> Stephanie WX3K
>>
>>
>>> On Aug 8, 2021, at 3:19 PM, Steve London <n2icarrl@gmail.com> wrote:
>>>
>>> This is a little off topic from the usual, but the expertise in DFing on
>>> this forum is outstanding.
>>>
>>> I am a serious contester, and do lots of SO2R. That means I need to be able
>>> to listen on one band while transmitting on another band. With filters and
>>> stubs I have brought the harmonic and overload energy down to acceptable
>>> levels. However, I have recently developed a new problem. Something on the
>>> tower is intermittent and causing the level of the 2nd harmonic to vary
>>> many S-units as the wind blows or I turn the rotator on the 40 meter beam.
>>> When this happens it creates hash across the band. I have looked for the
>>> obvious, but no luck yet. Yes, it could be something loose on the 40 meter
>>> beam hardware, but before I take on the project of taking it down, I would
>>> like to pinpoint the source. I am a tower climber, so I can get close to
>>> everything on the tower. What are the options for something handheld, very
>>> directional, and not overloaded by the fundamental ?
>>>
>>> 73,
>>> Steve, N2IC
>>> _______________________________________________
>>> RFI mailing list
>>> RFI@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/rfi
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|