| Author |
Message |
    
Kiwikid
| | Posted on Monday, December 29, 2003 - 2:42 pm: | 
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HiTeam,A word of warning with regards to PL259 to SO239 elbow connectors(right angle connectors)
Some manufactures make cruddy connectors that run an internal spring as the centre conductor,not visible from the outside,which does not make a good connection with the internal pins at each end.A friend detected his faulty connector when he was loading up the Ameritron and heard this sizzling noise.Very frustrating when the culprit was found after changing many other things first.These suspect connectors are difficult to detect when they are in sleep mode,not playing up.I found two brand new faulty ones with the aid of a ohms meter and opened one of them up with a hack saw.I have since taken them all out of my station and will replace with more expensive quality brand name ones.
Happy New Year and best of DX for 2004
from the South Pacific
73
CEF 195
Kiwi Kid |
Ca346
| | Posted on Monday, December 29, 2003 - 3:52 pm: |
|
Hey there John: (or if you prefer, KIWIKID)
Since you are practically in Australia, do you know the source of those defective PL259's? Was it Australia? China? Seems like we cannot get anything here in the U.S. made by anyone except the Chinese...
I have picked up alot of that stuff at my local radio shack, because it is a cheap item. Might be a mistake? |
Crafter
| | Posted on Monday, December 29, 2003 - 6:49 pm: |
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I think there all that way the one's I had wont hold power will work on just the radio but turn the amp on and look out! JUNK! |
Tech808
| | Posted on Tuesday, December 30, 2003 - 12:20 am: |
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AMPHENOL ONLY! FOR ALL COAX CONNECTORS.
AMPHENOL ELBOWS: AMPHENOL PART NUMBER #UG-646U
QUALITY COSTS a LITTLE MORE BUT WELL WORTH IT.
|
Ozzie
| | Posted on Tuesday, December 30, 2003 - 8:51 am: |
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Tech808,
Back in Australia I came across PL259 type plugs but made similar to N-type that is with seals and a removable center pin. Have you any idea for a source of similar here??
NOTE!
Ozzie. I will check my books for you and see what I can find for you.
Lon
Tech808
|
Kiwikid
| | Posted on Tuesday, December 30, 2003 - 2:07 pm: |
|
Hi Team,
Ca 346,
Either John or Kiwi Kid is fine with me,just use your preferance.I forgot to add that some new off the shelf were totaly OPEN CIRCUIT!
I would reckon that these suspect connectors came from somewhere in Asia.
Ozzie,
That PL259 sounds good but I have not seen that style of connector in this country.
Tech 808,
AMPHENOL are not the only manufacture of good quality coaxial connectors but are easier to obtain.
Hope to catch up with you good folk on the CEF nett your Sunday my Monday.
Once again:
Happy New Year and best of DX for 2004
from the South Pacific
73
CEF 195
Kiwi Kid |
Mr_Rf
| | Posted on Tuesday, December 30, 2003 - 6:39 pm: |
|
Beware, type N and PL259 elbow connectors used under high current (RF power) are a source of problem regardless of the brand...yes, even AMPHENOL FAIL!!!
The problem is this, when high RF currents travel down a transmission line and has to make a sharp 90 degree bend a mismatch in the bend will almost always occur due to manunfacturing/design issues. While this mismatch is minor to the overall system match seen at the antenna or transmitter, the sudden change in impedence due to the physical shape changing in the corners of most elbows (they loose their cylinderal properties and are usually more square in the corners of the bend) causes changes in heat dissipation along the line and and thus a change in movement of the center conductor. Adventually elbows that incorporate finger stock-to-pin connections (i.e. spring loaded terminals) loose their temper or "spring" effect, begin to arc, and adventually burn up, usually after roasting hundred's if not thousands of dollars worth of amplifier gear.
Elbows with "bent" but soild center conductors (no finger stock apprattus) usually end up melting and burning up in the bend of the center conductor. This is the "high stress" point of the RF path due to the significiantly increased impedence mismatch. A typical pre-indicator of this problem with silver plated connectors is the male, and sometimes the female, pin on the elbow will become unusually black in color, an excelerated tarnish look, which is exactly whats happening...it's aging faster due to the increased heat.
The moral of the story...if you're running more than a couple hundred watts you probably want to remove any elbows in the antenna line a just use the bend radius of your coaxial cable to do the job.
This has been my "20 plus years of commercial experience" RF lesson for the day, brought to you by, Mr. Unemployed himself...
Mr_RF
Good Day Mates P.S. I gotta get a job. Too much time on my hands! |
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