[Elecraft] KAT 500 Loses Match

[David Gilbert]

If you were putting 200 watts into it on FT8 that's almost three times 
the manufacturers rating and you're lucky you didn't fry it.

Dave   AB7E


On 1/14/2024 1:18 PM, Michael Reynolds, NO6O wrote:
> Actually, I was only putting around 200 into the antenna, and it's 
> doing fine.  I've been continuing to make digital contacts without the 
> amp and tuner.  The antenna works great for me.  I reached 50 
> countries during the past few weeks of testing.  Fortunately, I fully 
> understand what was going wrong.
>
> Michael, NO6O
>
>
> On 2024-01-14 1:03 PM, David Gilbert wrote:
>>
>> Fully agree.  The specs for the CHA-250B say a maximum of 75 watts 
>> for digital modes ... i.e., continuous duty modes.  That pretty much 
>> says what the actual heat dissipation capability is.  If he was 
>> trying to put 500 watts into his antenna in almost any mode, it is 
>> probably toast ... figuratively and literally.
>>
>> Dave AB7E
>>
>>
>> On 1/14/2024 8:17 AM, Morgan Bailey wrote:
>>> The Cha250 b is NOT an antenna capable of greater than 100 watts for 
>>> any
>>> length of time. It is a 5:1 unun hooked to a 23 foot aluminum 
>>> radiator. It
>>> needs to be 30 feet in the air and if that happens it will function 
>>> like a
>>> vertical OCFD. Still it is only good for 100 watts. When running a 
>>> tuner
>>> with the KAT500 and KPA500 you are heating up the puny unun and the 
>>> cores
>>> are totally being fried. Plus the reactance probably is generating high
>>> voltage on the short radiator causing arcs across any of the many
>>> connections inside the matching section. A guy fried a base section 
>>> and I
>>> have it in the garage. That is your problem. I have owned 2 of the 
>>> antennas
>>> and as such they work in a pinch and work well for fast POTA activation
>>> with 100 watts but other than that they are pretty much a megga 
>>> compromise
>>> antenna. You would be way better off with a 998 mfg remote tuner and 
>>> a 43
>>> foot vertical over a radial field. Check out the Zero5 antennas for the
>>> cheapest durable 43foot vertical solution. 73, Morgan NJ8M
>>> BS + MS + $2.98 = COFFEE
>>> Real Life Experience = Priceless, says the man who set his back yard on
>>> fire with a breadboard tuner loading a 160 meter inverted L with 1000
>>> watts. LOL
>>>
>>>
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>
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