[Elecraft] KPA500 and K3 SWR meters disagree

[Grant Youngman]

Have you replaced the coax cable between the KPA500 and the KAT500?  


Sent from my iPhone

> On Jun 2, 2018, at 5:04 PM, jeff griffin <kb2m at arrl.net> wrote:
> 
> Hi Jack. The swr is so different between the two that there has to be a
> problem. I've had this setup for 3 years and never experienced this
> behavior.
> 
> 73 Jedff kb2m
> 
> -----Original Message-----
> From: Jack Brindle [mailto:jackbrindle at me.com] 
> Sent: Saturday, June 2, 2018 4:47 PM
> To: jeff griffin
> Cc: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] KPA500 and K3 SWR meters disagree
> 
> Jeff;
> 
> Do I understand that for the first test you are driving the antenna through
> the KPA500 and KAT500 (with KAT500 in bypass)? If so, it makes a lot of
> sense that you will see different SWR. The KPA and KAT are providing a
> completely different load for the K3. The better test is to feed the antenna
> directly from the K3 without the KPA and KAT in-line. I would expect you to
> see a closer match at that point, although I doubt they will ever be
> identical due to the differences in the directional couplers in the K3 vs
> the KAT500 (and KPA500 for that matter).
> 
> Jack, W6FB
> 
> 
>> On Jun 2, 2018, at 8:48 AM, jeff griffin <kb2m at arrl.net> wrote:
>> 
>> I recently brought my KPA/KAT500 north for the summer and hooked up to my
> trapped multiband fan dipole that I use here in NJ. I leave my K3 here for
> remote use and use the amp at my winter home in Florida to use with my Flex
> 6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up
> here I installed the KIO3B option. The install went well with no issues, all
> looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft
> provided cable set like I do every year. 
>> 
>> The issue I'm having is an SWR difference between the KAT500 and the K3.
> For example if I use the K3's internal tuner I can on a chosen frequency
> achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and
> take the KAT500 out of bypass and set to auto. I then use the xmit button on
> the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a
> 1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows
> around 3/1. What this causes to happen is the Amp will fault out if I try to
> use any power output. If I check the antenna with a trusted SWR meter I see
> 1.3/1 at the frequency of use. I upgraded the firmware in all the devices in
> use, I also did a reset of the KAT's stored frequencies memory, and checked
> both the amp and tuner with the utility programs. I'm going to call Elecraft
> on Monday, anyone have any ideas in the meantime I can try?
>> 
>> 73 Jeff kb2m   
>> 
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