[Elecraft] New from Elecraft: KPA1500 amplifier with built-in ATU, separate power supply

[Wes Stewart]

Without modeling it, I would guess that it will actually narrow the matched BW 
and it makes it a single band antenna at the same time.

My Drake L4-B would drive anything.  When I decided I needed a new challenge 
(9BDXCC) I wanted to get on 160.  Of course the Drake didn't cover 160 and my 
then K3, now K3S doesn't have a tuner.  So I added some wire to the ends of the 
80-meter inverted V.  This meant that I didn't have an 80-meter antenna but the 
Drake would drive it anyway.  Currently, with a KPA500 and KAT500 I have modest 
power on 160 but the KAT500 chokes on 80 at above 200-300 Watts.

Hence the new vertical for next season.

On 4/21/2017 11:10 AM, john at kk9a.com wrote:
> It is very easy to put a hairpin coil on your top band vertical and bring
> the resonant SWR to 1:1. This should give you much more usable SWR
> bandwidth for the KPA1500. Many commercial tube amplifiers will only
> tolerate 2:1 SWR.
>
> John KK9A
>
>
> >From Wes Stewart n7ws
> Fri Apr 21 13:11:12 EDT 2017
>
> I'm not necessarily defining a personal situation.  But almost any 80 or 160
> antenna will suffice as an example.
>
> I am currently constructing a vertical for those bands.  The model shows
> 2:1 on
> 160 at resonance and >3:1 just 60 KHz away and this is with considerable
> ground
> loss.  Less loss would equal lower BW.  With quarter wave resonance on 80
> at 3.6
> MHz it exceeds 3:1 at 3.8 MHz and is nearly 7:1 at 4.0.
>
> Transmission line loss is a non-issue with 7/8" Heliax.
>
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