[CQ-Contest] calculating CW duty cycle

[Robert Busch - DM4AO]

Hi Darrell,

What about vertical dipole(s) on a small fibre glass pole (I love the Mini from DXwire)? You can put as much power on it as your coax can cope and you can put it up everywhere. Omnidirectional, low take off angle, no radials, easy to construct and easy to carry!

Don‘t forget: The best amp is your prefix, hi!

73
Rob, DM4AO


Robert Busch   .iPhone
___________________
Mind is like a parachute, it only works when it's open.

> Am 05.07.2022 um 04:28 schrieb AB2E Darrell <ab2e at hotmail.com>:
> 
> Greetings John & the group,
> The antenna in question is the PreciseRF HG3 QRO, an MLA loop, advertised at 1500W.
> When I dug into the actual specs, it's 50% duty cycle for CW at 800W, and 25% duty cycle at 1500W.
> I would be using an SPE 1.5K-Series III amp, so will likely have to run it in the low power position, driven by an Elecraft K3.
> That's OK, still 6db stronger than 100W.
> 
> Now that I'm 70, I'm having to rule out a lot of stuff I could do before due some developing health issues.
> Now maybe I'm better off taking a chance and trying to string a dipole between 2 palm trees rather than trying this MLA, but my recent
> experiences with AirBnb's in a couple islands, I've gotten negative responses to my inquiries about putting up antennas.
> Most of the great rent-a-shacks are always occupied, or sky high in price.
> 
> The HG3 QRO takes up minimal space and could be set up easily in the back yard of the villa without attracting attention.
> Yes, I know all these things involve tradeoffs, but may mean the difference between getting to go somewhere and operate or not.
> 
> 73 to all,
> Darrell AB2E
> 
> ________________________________
> From: CQ-Contest <cq-contest-bounces+ab2e=hotmail.com at contesting.com> on behalf of john at kk9a.com <john at kk9a.com>
> Sent: Monday, July 4, 2022 9:47 PM
> To: cq-contest at contesting.com <cq-contest at contesting.com>
> Subject: Re: [CQ-Contest] calculating CW duty cycle
> 
> I would guess that running a pileup your CW duty cycle would be closer to
> 25%.  What is the antenna and why is the power level so questionable?  FWIW,
> I have never had an issue setting up a Yagi, dipole or beach mounted
> vertical from a Caribbean villa.
> 
> John KK9A
> 
> 
> 
> AB2E wrote:
> 
> The consensus is that even with the variables, the duty cycle will not
> likely be over 50% at my regular contest speed of 30-35wpm.
> The reason for my question is that I am evaluating a portable antenna that
> claims a 50% duty cycle at 800W,
> but drops to 25% duty cycle for CW at 1500W. It appears I should be OK
> operating around 600-700W safely with the 50% duty cycle.
> This would be used on an island dxpedition where putting up regular (proper)
> antennas would not be possible, probably from a villa.
> 
> 73 and thanks again for taking the time to answer,
> Darrell AB2E
> 
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