[CQ-Contest] Coax Stubs for SO2R

[Joe]

Really? 200+ Euros? And coax made homebrew stubs are not much cheaper? HUH?

Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 7/25/2016 4:53 PM, Rudy Bakalov wrote:
> Jukka, Jim, and Steve,
>
> Thank you for taking the time to go into details. What's clear to me 
> that the non liner AB type of amps contributes significantly to 
> harmonics along with improper amp loading/tuning.
>
> As I mentioned earlier I already have BPFs so now I am left with the 
> mechanical challenge of stubs. Specifically, will have to follow 
> Jukka's advice on adding coax between the remote SO2R switch and the 
> antennas.
>
> Honestly, I even wonder if the hassle of building and placing two sets 
> of stubs (it seems the opinion is that two are needed) is really that 
> much cheaper compared to buying high power BPFs. Between Remo's 
> filters and the link below there are affordable alternatives to 
> Ranko's BPFs:
>
> http://www.antennas-amplifiers.com/Band-Pass-Filter
>
> For €1200 one can have plug and play filtering (although I may run 
> into components' thermal properties when the filters are outside by 
> the tower) that is not critical with respect to placement along the 
> feed line.
>
> Who sad ham radio is a hobby; feels like serious engineering work to 
> me :-)
>
> Thank you all for your patience.
>
> Rudy N2WQ
>
> Sent using a tiny keyboard.  Please excuse brevity, typos, or 
> inappropriate autocorrect.
>
>
> On Jul 25, 2016, at 4:41 PM, Jukka Klemola <jpklemola at gmail.com 
> <mailto:jpklemola at gmail.com>> wrote:
>
>> Hi,
>> I try give simplified answers ...
>>
>> This should answer also Rudy's question.
>>
>>
>> 2016-07-25 15:47 GMT+03:00 Joe <nss at mwt.net <mailto:nss at mwt.net>>:
>>
>>> This also puzzles me.
>>> OK if an amp because of it's tuned matching circuits, block out of band
>>> energies
>>
>>
>> Amplifier circuits attenuate unwanted band energy.
>> But to a limit.
>> A Pi filter attenuates to some level, Pi-L attenuates more.
>> If that is not enough, we need additional attenuating, that is additional
>> filtering like a stub
>>
>>
>>>
>>>
>> The why do we have these energies at all in the first place?
>>>
>>
>> When amplifying a signal in an amateur amplifier, the plate current when
>> only PTT is activated is less than a quarter of plate current with 
>> maximum
>> specified signal that is amplified.
>> It means there is plate current through most of the sine wave signal 
>> cycle,
>> but not all of it.
>> It means there is a sharp corner in the output signal .. it is not a 
>> clean
>> sine wave.
>> Such signal with such corners has harmonic energy.
>> This energy propagates towards the antenna connector.
>> It travels through the output circuit; most often Pi or Pi-L.
>> On an oscilloscope, the signal looks pretty much like a sine wave but it
>> contains harmonic energy.
>>
>> Sorry, but this gets more complex when digging deeper.
>> Next step would require you to read some books or at least web sites.
>>
>> Easy to understand information packages are ARRL hand book and Orr/W6SAI
>> Radio Handbook.
>>
>> ARRL handbook is easy to find and purchase.
>> I would suggest to try and find also a paper book:
>> http://www.eham.net/reviews/detail/3963
>>
>> W2VJN book is a must if you want to understand more about RF filtering
>> needs at a multi radio station.
>>
>>
>> ** Encouragement, keep it simple message:
>> As we are hams, we can use ready made recipes for stubs, among many other
>> things.
>> That is allowed for us and us hams, we can just accept many things as 
>> given
>> facts.
>>
>>
>> Does not a Radio have the equivalent of an "Exciter" ( the ummm low level
>>> driver )
>>
>>
>>> And the "AMP"  ( the final output amplifying system )
>>>
>>> So, if all this filtering is happening why do we have spurious out 
>>> of the
>>> radio, but not an amp?
>>>
>>
>> There are a lot more signals in the radio than the mains input and RF
>> connector with RXinput / TX output.
>> To start with, the radio's oscillator is not on your actual output
>> frequency.
>> There are other oscillators, mixers, filters, amplifier circuits, more
>> filters and so on inside your transmitter before the antenna connector.
>> All those are creating or limiting spurious signals and we need to 
>> engineer
>> the radios so the radios do not emit unnecessary signals and we engineer
>> our radios so they do not input unnecessary signals or at least the radio
>> does not care about the unnecessary/unwanted signals.
>> Emissions are emissions; intended or spurious.
>> The receiving side phenomena are under words immunity or susceptibility.
>> Together they are electromagnetic compatibility EMC.
>>
>> These spurious signals propagating from device to another device can 
>> be as
>> bad as K1EA described about the radios they used.
>> The radio2radio signal propagation happened on a set of phenomena 
>> caused by
>> some radio internal signalling leaking through radio wiring and 
>> propagating
>> to another radio so the receiver of the other radio heard the 
>> transmitting
>> radio signal regardless the frequencies the radios were on,
>> That is a really puzzling situation and typically difficult to overcome.
>> Most likely the leaking and injecting mechanism was through antennas
>> connected to radios but not necessarily. That kind of electromagnetic
>> incompatibility should be rare, though.
>>
>> After Ken K1EA et al added RF and maybe also other filtering, the radios
>> stopped hearing each other that badly.
>>
>> Other filtering are for example ferrites we place on DC power cords, 
>> mains
>> wires and other .. PTT / band data and any other wiring you have at your
>> station. We attenuate unwanted signals until they do not bother us.
>> You can find a lot of information about different kinds of filtering 
>> in the
>> internet.
>>
>> All cases are different.
>>
>> Some hands-on information here:
>> http://wiki.k1ttt.net/Default.aspx?Page=2008%20Maintenance%20and%20Upgrade%20Blog&NS=&AspxAutoDetectCookieSupport=1
>>
>> Look for words
>>  -harmonic
>>  -power
>>
>>
>>
>>>
>>> Joe WB9SBD
>>>
>>
>>
>> 73,
>> Jukka OH6LI
>>
>>
>>> Sig
>>> The Original Rolling Ball Clock
>>> Idle Tyme
>>> Idle-Tyme.com <http://idle-tyme.com>
>>> http://www.idle-tyme.com
>>> On 7/25/2016 5:48 AM, Rudy Bakalov via CQ-Contest wrote:
>>>
>>>> Jukka,
>>>>
>>>> It is the statement below that really puzzles me. All amp people I 
>>>> know,
>>>> including those that manufacture commercial amps, categorically 
>>>> state that
>>>> amps do not generate harmonics on their own. That is, amps merely 
>>>> amplify
>>>> them.
>>>>
>>>> To me this seemingly minor difference is huge. If amps only amplify but
>>>> do not generate harmonics then there is no scientific reason for 
>>>> filtering
>>>> after the amp assuming the same amount of filtering is applied 
>>>> before the
>>>> amp. In practical terms, this would mean that low power BPFs before 
>>>> the amp
>>>> are as effective as high power BPFs after the amp.
>>>>
>>>> The key point here is GENERATE vs AMPLIFY harmonics. Can the average
>>>> commercial, well stabilized amp generate harmonics?
>>>>
>>>> Rudy N2WQ
>>>>
>>>> Sent using a tiny keyboard.  Please excuse brevity, typos, or
>>>> inappropriate autocorrect.
>>>>
>>>>
>>>> On Jul 24, 2016, at 5:14 PM, Jukka Klemola <jpklemola at gmail.com 
>>>> <mailto:jpklemola at gmail.com>> wrote:
>>>>>
>>>>> In case you do that, you still need stubs after the amp.
>>>>> Amplifier creates harmonics out of the fundamental frequency.
>>>>>
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>>>>
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