http://elecraft.85.s1.nabble.com/Re-NOT-the-feedline-was-KPA-1500-faulting-on-6m-SWR-issues-tp7661502p7661572.html
Yes, the UHF connector may be rated at 500V, but in practice they handle >4KV. The voltage limit is set by the air gap between the center pin and the shield. I have not had a PL-259 arc over.
Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a UHF connector. Type N connectors are rated at 1500 V peak.
> On Jun 1, 2020, at 3:17 PM, George Kidder <
[hidden email]> wrote:
>
> One of my antennas is a commercial "G5RV" fed with 33' of 450 ohm ladder line, terminated in a PL-259 pair, with coax from there to the shack. Apparently this combination results in very high RF voltage at the PL-259, and it arcs over at 1000 W (not from an Elecraft amp!). This combo goes wild when I attempt high power on 80M, although it is stable at 100 W. Just another thing to watch out for!
>
> 73 - George, W3HBM
>
> On 6/1/2020 5:59 PM, Ted Edwards W3TB wrote:
>> [This message came from an external source. If suspicious, report to
>>
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>>
>> I am following this with great interest.
>> Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in
>> this case, 300 ohm to the antenna. K3, KPA-500 and KAT-500.
>>
>> If I am running stations in a contest on 40m and also 80m CW, It "appears"
>> that my VSWR rises after a half hour and then the KAT-500 starts to
>> try to spontaneously retune. Doesn't happen on 20m and up. This
>> past weekend in CQ WPX, I reduced drive so that output was about 300
>> watts and it all became tame.
>>
>> I had thought that it was a heating of the RG-8X; then I changed my
>> mind to the current balun from Radiowavz that is rated for 1.5 KW. I
>> think it is the balun just getting hot out there. I had used a W2AU
>> 4:1 balun with my OCF, which is a voltage balun but I didn't know
>> about that -- for upwards of 40 years and with the Elecraft equipment
>> for about 4 years since I got the amp/tuner. I just switched to a
>> current balun last year with one that I bought at Dayton.
>>
>> I would have expected more problem with the voltage balun than with
>> the current balun. I could change back to the W2AU if needed.
>>
>> Interesting stuff, so I am reading along. And my thanks to all of you.
>>
>> On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen <
[hidden email]> wrote:
>>
>>> Nearly same experience Bob: Sloping V, 135 ft legs, from top of 80
>>> ft tower fed with homemade 600 ohm open wire using a DX Engineering
>>> 4:1 "balun" [a strange, usually misunderstood piece of electronic
>>> apparatus often used for the wrong reasons] rated at 10 KW. It
>>> warmed up noticeably at 1.2 KW RTTY use. It helps to remember that
>>> one can saturate a ferrite core [especially when very hot] which
>>> creates a racket reminiscent of a non-synchronous spark gap TX.
>>>
>>> 73,
>>> Fred ["Skip"] K6DGW
>>> Sparks NV DM09dn
>>> Washoe County
>>>
>>> On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
>>>> Based on my experience, balun power ratings are for MATCHED
>>>> conditions. It is rare that hams use a balun in a matched condition.
>>>> Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on
>>>> the output, while a 4:1 balun should see 200 ohms on the output and 50
>>>> ohms on the input. In the case of a resonant folded dipole, a 4:1
>>>> balun is typically operating in a nearly matched condition. All
>>>> others combinations are unknown and random.
>>>>
>>>> I run about 500 watts on all bands. My baluns are rated at 5KW! It
>>>> takes 3 or 4 big hunkin' pieces of ferrite to attain this power
>>>> level. My 6 meter balun is a 1/2 wavelength electrically of RG-213.
>>>> No ferrite!
>>>>
>>>> Buy or build a balun of your choice. Using an IR temperature gun,
>>>> measure the ambient temperature of the core. Run about 1/2 rated
>>>> power carrier for 30 to 60 seconds. Measure the temperature again.
>>>> If it is warm to hot, this is RF producing heat. And likely
>>>> continuing will produce core failure. This is not a good balun for
>>>> your application.
>>>>
>>>> One of my baluns work between the output of my KAT500 and the
>>>> balanced feed line connected to the center of a 256 ft wire. That antenna
>>>> works 160M - 6M with zero issues. Now, I do run a hybrid balun being
>>>> a 4:1 Guanella balun as a transformer, and it is fed with a 1:1
>>>> balun for common mode rejection.
>>>>
>>>> Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are
>>>> not at all a proper balun design A Guanella balun will have 2 cores
>>>> with 2 windings and then another 2 separate cores with another 2
>>>> windings. These are then wired to produce a 4:1 balun with good
>>>> common mode rejection. Most "factory" 4:1 baluns are poorly
>>>> designed and built junk.
>>>>
>>>> See
https://www.dj0ip.de/balun-stuff/ for further references.
>>>>
>>>> 73
>>>>
>>>> Bob, K4TAX
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>>
>> --
>> 73 de Ted Edwards, W3TB and GØPWW
>>
>> and thinking about operating CW:
>> "Do today what others won't,
>> so you can do tomorrow what others can't."
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