[Elecraft] 80m KPA1500 High reflected power problems

[Jamie WW3S]

Any cheap bulkhead connectors in the feed? I just got burnt by one on my radial plate....

Sent from my Verizon Motorola Smartphone
On Mar 9, 2019 2:04 PM, Don Wilhelm <donwilh at embarqmail.com> wrote:
>
> Peter, 
>
> Isolate the problem to the amplifier.  Get a high power dummy load if 
> you do not already have one.  Run the amp at 1000 watts or more into the 
> dummy load.  If the amp behaves the same as it does with the antenna, 
> then the problem is in the amplifier. 
> But if the amp behaves into the dummy load, look for marginal 
> connections to your antenna, PL-259 connectors not sufficiently 
> tightened, balun overload, arcing at either the center insulator or at 
> the end insulators. 
> There is very high RF voltage at the antenna ends, and it may be arcing 
> over the end insulators - don't overlook that possibility. 
>
> 73, 
> Don W3FPR 
>
> On 3/9/2019 1:50 PM, Peter Dougherty wrote: 
> > HI guys, 
> > I'm still having a serious problem on 80m with my KPA1500. 
> > 
> > With the amp inline I'm getting high reflected power fault everywhere below 
> > about 3675. My antenna (an inverted vee) is resonant at 3550, and the SWR is 
> > below 2:1 from 3500 to 3630. 
> > 
> >   
> > 
> > This was happening in the past as well, and prompted me to completely 
> > rebuild the antenna last summer. The antenna is fed with 100' of brand new 
> > Davis BuryFlex feedline, a brand-new 5kW-rated Balun Designs 1:1 current 
> > balun, new 12 AWG copper-clad steel wire, even new heavy ceramic insulators! 
> > 
> > 
> > Without the amp everything's fine. I can push 100W through to the antenna 
> > all day; the SWR LEDs on the amp (bypassed) show two green and that's it. 
> > It's fine on every other band, including 80/75 phone. 
> > 
> >   
> > 
> > With the amp in, If I drop the drive to 10W or less, the amp is happy and I 
> > get about 450 Watts out. But the instant I drive it with ~15 Watts (when the 
> > K3s kicks the high power module in, and I hear the internal relay click, I 
> > get the HI SWR warning and the amp faults. 100% repeatable. Doesn't matter 
> > if the tuner is in or out..there's NO way to get high power out of the KPA 
> > on 80 CW. 
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