[Elecraft] KX3 - SWR Display of "--"

[Matt VK2RQ]

Thanks Dick, that's good to know. It makes sense to include an SWR bridge in the basic amplifier, because then you can provide protection against antenna faults and other high SWR conditions.

73, Matt VK2RQ.

> On 22 Nov 2014, at 7:01 am, Dick Dievendorff <dick at elecraft.com> wrote:
> 
> Sorry Matt, this isn't quite right.
> 
> The KXPA100's SWR bridge is on its LPF board, and is part of all KXPA100's,
> with or without the  KXAT100 Antenna Tuner Option.
> 
> The KX3 currently doesn't display the KXPA100's SWR, it instead displays the
> KX3 SWR measurement. 
> 
> When the KXPA100 is PA Bypassed (under about 10 watts), the KX3 SWR bridge
> sees the antenna impedance, so the SWR display is appropriate.  However when
> the KXPA100 is not bypassed, the KX3 SWR display is of the input of the
> KXPA100.
> 
> Wayne has on his KX3 firmware "todo" list a task to display KXPA100 SWR on
> the KX3 display when appropriate.
> 
> The KX3 displays dashes when its power is too low for an accurate SWR
> measurement.
> 
> The KXPA100's view of the antenna system SWR can be displayed with the
> KXPA100 Utility Operate Page, LEDs on an KXAT100-equipped KXPA100, or an
> external SWR meter like our W2.
> 
> 73, Dick, K6KR
> 
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Matt
> VK2RQ
> Sent: Friday, November 21, 2014 11:36 AM
> To: stan levandowski
> Cc: Elecraft
> Subject: Re: [Elecraft] KX3 - SWR Display of "--"
> 
> Above 10W of power, the KX3 will disable the internal KXAT3 ATU and rely on
> the amplifier to supply the SWR readings over the ACC1 cable. However, the
> SWR bridge for the amplifier is part of the KXAT100 ATU option for the
> amplifier, so if this option is not equipped, the amplifier will not be able
> to supply any SWR readings. I'm guessing this is the reason you are seeing
> the '--' dashes for SWR when operating above 10W. If the behaviour is
> intermittent, it may indicate a problem with your ACC1 cable connection.
> 
> 73, Matt VK2RQ
> 
>> On 22 Nov 2014, at 3:06 am, stan levandowski <sjl219 at optonline.net> wrote:
>> 
>> I just got a KXPA100 yesterday.  It seems to work as specified except that
> above 10 watts of power, the KX3 display randomly {like in "not all the
> time"} shows two dashes instead of the SWR. 
>> 
>> I do not have the internal tuner option.  I am using my SGC237 autocoupler
> into a center fed Zepp.  My W2 wattmeter shows the proper power output and
> the SWR  is usually 1:1 or very close.
>> 
>> This does not occur at power levels at or below 10 watts which means it's
> most likely not the KX3's problem but rather the amplifier's behavior.
>> 
>> Happens on different bands and frequencies.  If this is documented
> somewhere then I've missed it.
>> 
>> 73, Stan WB2LQF
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