Dear All,
The below mail also be of interest:
-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Eric Swartz - WA6HHQ,
Elecraft
Sent: 11. maj 2011 20:10
To: Geoffrey Downs
Cc: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 and SWR above 1.5:1
The KPA500 bases its SWR protection on reflected power level, not an
absolute SWR. The KPA500 is happy up to a 2:1 SWR at 500-W out. As long as
the actual reflected power is below that for a 2:1 SWR at 500W, it will not
reduce its power. This means you can operate into a higher than
2:1 SWR load at full amplifier gain if you reduce the amp's output power
slightly.
The amp soft-faults and reduces output power by about 2.5 dB by switching
in an input attenuator at the 500W 2:1 reflected power point, and it flashes
a red LED to alert you to this so you can adjust driver power (or SWR via an
external tuner) down a bit. Once this is corrected below this threshold by
the operator, the KPA500 automatically goes back to full gain. It also does
this for minor overdrive conditions.
Of course, for excessive SWR events (wrong antenna, open antenna etc), and
severe overdrive, the amp protects itself by immediately hard faulting and
going into bypass mode. After correcting the fault, just push the
operate/standby switch to get back on-line. While at Contest University, our
Italian representative surprised me by demonstrating this feature to
customers by pulling the coax from the dummy load while the amp was
transmitting. After I recovered from my surprise, I realized the amp was
perfectly happy and had protected itself as advertised :-) But don't try
this at home, as he also received a minor RF burn to help him remember this
event..
73, Eric WA6HHQ
www.elecraft.com
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Gary Gregory
Sent: 30. juni 2011 08:31
To: j...@audiosystemsgroup.com
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 tolerance
I can confirm Jims findings also1.8:1 is fine here also.
Gary
On 30 June 2011 04:12, Jim Brown j...@audiosystemsgroup.com wrote:
On 6/29/2011 7:43 AM, jgaudron wrote:
A friend of of mine has problems with a solid state amplifier that
switches
to safety at the least value of SWR, like 1.2 or 1.4 !
He would like to know what is the KPA500 tolerance concerning SWR.
My KPA500 puts out 600W - 675W (I've seen occasional peaks of 700W
without faulting) into a reasonably matched load on the HF bands
(1.5:1 or better), and 560W on 6M into a load of about 1.4:1. If the
match
gets to about 2:1 on the HF bands, it might fall back to 500-550w. No
issues with nuisance faulting.
73, Jim K9YC
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net Please help support this email
list: http://www.qsl.net/donate.html
--
VK4FD - Motorhome Mobile
Elecraft Equipment
K3 #679, KPA-500 #018
Living the dream!!!
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
