[Elecraft] KAT500 SWR LED Doesn't Light with 1.0/1 SWR

[Bill Johnson]

Dick, thank you for jumping in.  Has been a long time since I used the KAT500 now that KPA1500 is in the shack!

72 & 73,
Bill
K9YEQ
FT'er for K2, KX1, KX3, KXPA100,  KAT500, W2, etc. 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of dick at elecraft.com
Sent: Saturday, April 6, 2019 4:36 PM
To: 'wmbrian' <bdeuby at gmail.com>; elecraft at mailman.qth.net
Subject: Re: [Elecraft] KAT500 SWR LED Doesn't Light with 1.0/1 SWR

Brian:

Your KAT500 low order SWR LED, labeled "1.2", is illuminated when there is a little bit of forward power and an SWR of 1.2:1  or higher is computed.  If the SWR is under 1.2:1, then no KAT500 SWR LEDs are illuminated. Even 500 watts of RF with little or no reflected power shouldn't light any KAT500 SWR LEDs.  The KPA500 (and KPA1500) have an SWR bar LED for 1.0.  The KAT500's first SWR LED is 1.2.

Fred's book is correct; your KAT500 performs an SWR calculation whether or not the ATU is bypassed. That result can be displayed with the KAT500 Utility Operate page, or any other program that can send a command to the
KAT500 to read its SWR. If SWR is 1.2:1 or higher, then it's also displayed on KAT500 SWR LEDs. 

73 de Dick, K6KR
 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of wmbrian
Sent: Saturday, April 6, 2019 11:02
To: elecraft at mailman.qth.net
Subject: [Elecraft] KAT500 SWR LED Doesn't Light with 1.0/1 SWR

I recently added the KAT500 and KPA500 to my K3 station. 

I have noticed that when the SWR (after tuning)  as displayed on the KPA500 is 1.0/1  (or occasionally 1.1/1) no SWR LED lights up on the KAT500. (The green 1.0/1 SWR LED on the KPA500 does light up.)

I have assumed that the 1.2/1 KAT500 SWR LED does not light up is because 1) the KAT500  threshold for the first SWR LED is 1.2/1 and 2) because no tuning action has taken place in these circumstances (due to memorized
KAT500 tuning configuration).  However, I noticed at the bottom of page 49 of Fred Cady's book on the KAT500 and the KPA500 it says "VSWR is displayed even when the tuner is bypasssed". So, I'm confused. Does no SWR LED light when the SWR is 1.0/1 (or very close to it) because the SWR is below 1.2/1?

Thanks,

Brian, K8GRR



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