Dave;
Check the ferrite cores. There is a very good chance that they overheated and
cracked.
Check K9YC’s manual for more information here. Jim’s advice as to the
connectors is
excellent as well. Usually a problem there is from arcing, and will show up in
the KPA500
as a high reflected power fault. If the problem exists at low power, then I
would suspect the balun.
73,
Jack, W6FB
> On Jul 3, 2022, at 5:43 AM, Dave Sublette <k4to.dave@gmail.com> wrote:
>
> I just checked the coax I used. It has the stranded center conductor. I
> can't find the part number on it. I would hve to find the invoice. But it
> is the mil spec teflon/silver coax.
>
> K4TO
>
> The antenna is working now. I'm suspecting the relay position on the
> remote switch. As soon as it stops raining, I will check it out. Thanks
> for for all the advice.
>
> K4TO
>
> On Sat, Jul 2, 2022 at 11:57 PM Grant Saviers <grants2@pacbell.net> wrote:
>
>> A minor matter, but RG142 center conductor is SCCS - silver plated
>> copper coated steel. That makes it very strong but fatigue prone. Some
>> are concerned about TFE creep from the solid conductor and recommend
>> stranded RG400 as a result. However, I've not had problems in FT-240
>> toroid chokes wound 10 years ago with 142 made from Mil 17/60-RG142 spec
>> cable.
>>
>> Paternack specs their 142 at 2400w average power at 100MHz. It will get
>> hot, but the TFE handles it. Best to provide easy dissipation of the
>> heat as K9YC recommends.
>>
>> Another possible issue is to keep ferrite toroids away from the boom and
>> other conductors as the coupling can cause problems.
>>
>> Grant KZ1W
>>
>>
>> On 7/2/2022 16:13, Jim W7RY wrote:
>>> Agreed.
>>>
>>> RG-400 works well to. The only difference between RG-142 and RG-400, is
>>> that RG-400 has a stranded center conductor. RG-142 has a silver plated
>>> solid hard drawn copper center conductor.
>>>
>>> 73, Jim W7RY
>>>
>>>
>>> On 7/2/2022 6:09 PM, john@kk9a.com wrote:
>>>> The 50MHz power average rating for RG142 is several kilowatts, why do
>> you
>>>> think it is inadequate?*If it is a balun problem it is most likely
>>>> connection related.*
>>>>
>>>> John KK9A
>>>>
>>>>
>>>>
>>>> Dave Sublette k4to wrote:
>>>>
>>>> My six element 6M LFA is showing a high SWR and severe loss of receive
>>>> signal. This happened this afternoon as I was working the band with 500
>>>> watts from my KPA500.
>>>>
>>>> To this point, the antenna was very nicely matched with a 1:1 SWR over
>>>> almost 1 MHz of bandwidth. The antenna is home brew and I made the
>>>> matching
>>>> balun per the instructions from K9YC using two toroids with six turns
>>>> each
>>>> of high quality teflon insulated, double shielded silver braid. I
>>>> think it
>>>> was RG142 purchased new from a reputable vendor in Tennessee. It has
>>>> worked
>>>> perfectly at the 100 watt level for three or four years. I had looked
>> at
>>>> the specs on the coax and thought it would be good for 500 watts.
>>>> Evidently not.
>>>>
>>>>
>>>> 73,
>>>>
>>>> Dave, K4TO
>>>>
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