Joe
You make perfect points here!
No doubt the gamma was designed around a KW power level but the reality is, it
was probably ok for 500 watts. Power limit was 1 KW input with 50% efficiently,
a 500 watt design target was the case. Now envision 1500 output to the antenna
feed point. Yep you will have problems!
Other related Cushcraft power limits come with the A3/A4 tribanders- no more
than 1200 watts here.
Regards,
Mark, K1RX
> On Jul 31, 2022, at 9:51 AM, Joe Subich, W4TV <lists@subich.com> wrote:
>
>
>> On 2022-07-31 9:01 AM, Pete Smith N4ZR wrote:
>> It looks to me that this limitation might relate to the feedline connection,
>> which is a bulkhead SO-239 (mounted with a big nut) bracketed to the center
>> of the driven element.
> I would bet that the limitation is due to the breakdown of the
> dielectric in the gamma match (capacitor). CushCraft used a
> rod from the center conductor of the UHF connector through a
> dielectric tube inside an aluminum tube that formed the outside
> of the gamma match.
>
> If 1KW is a real limitation, I doubt that you can do anything
> to improve it except redesign the antenna for a split driven
> element and 50 Ohm feed. That 7' boom would make a nice 4 element
> OWA.
>
> 73,
>
> ... Joe, W4TV
>
>> On 2022-07-31 9:01 AM, Pete Smith N4ZR wrote:
>> I have just bought a small Cushcraft 3-element 6-meter yagi. Only small fly
>> in the ointment is that it is *only* rated at 1 KW. It looks to me that
>> this limitation might relate to the feedline connection, which is a bulkhead
>> SO-239 (mounted with a big nut) bracketed to the center of the driven
>> element.
>> My question is, do I need another connector here, or maybe insulation
>> between the bracket and the element? If so, what material makes sense? Any
>> other advice?
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|