[Elecraft] Question re TXMON

[Alan Bloom]

The waveform display in the P3 TX monitor auto-ranges to keep the 
modulation peaks within the display limits.  However, if the forward 
power gets high enough to over-range the ADC, then the waveform will be 
clipped.  With the 200W HF sensor, I believe the clipping level is about 
240-250 watts, depending on the calibration.

With 100W out of the K3 and assuming 100% efficiency in the tuner, the 
SWR would have to get up to about 7.7:1 to cause clipping of the 
displayed waveform.

Alan N1AL



On 06/07/2016 01:23 PM, Bob Novas wrote:
> I wondered if a high SWR affects the waveform that the P3 displays -
> wouldn't the voltages be higher at high SWR?  would that put the txmonitor
> into a non -linear region?
>
>> -----Original Message-----
>> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Alan
>> Bloom
>> Sent: Tuesday, June 07, 2016 3:29 PM
>> To: elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] Question re TXMON
>>
>> There is no reason to disconnect the P3 from the sensor.  The sensor can't
>> damage the P3.
>>
>> I suppose there might be a danger of damaging the sensor if you are
> running
>> high power into a very high SWR, but if it is in a range that the K3 ATU
> can tune, I
>> can't imagine there would be a problem.
>>
>> Alan N1AL
>>
>>
>> On 06/07/2016 10:37 AM, Steve via Elecraft wrote:
>>> I have recently added P3 to my K3 and (surprise!) I love it.  My
>>> (previously owned) P3 came with TXMON. TXMON works fine with dummy
>>> load, but  often shows very high SWR readings when K3 ATU is used with
> non-
>> resonant  antenna.
>>> I understand that the TXMON "looks at" antenna and doesn't know what
>>> ATU is doing. My question is, "Is there any problem or danger to leave
>>> the TXMON connected when using ATU on non-resonant part of antenna
>>> bandwidth? My reason to  ask is that tab to release TXMON sensor plug
>>> is right up against top
>>> RS232 plug  and I need to disconnect that plug in order to disconnect
>>> TXMON sensor  cable.
>>>
>>> TNX ES 73 de W3UEC (Steve)
>>>
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>