[Elecraft] Bigger K3 S-meter

[K7TV]

I just came across another situation where the K3 S-meter wasn't doing the
job.
Bought an MFJ noise canceller (works at receive frequency, using a separate
noise pickup antenna). The reason that the purchase came about *now* was
that, unlike my other rigs, the K3 has this wonderful RX antenna loop, where
the noise canceller can be inserted without worries about transmitting
through it.  On the device you adjust an amplitude control for each antenna
such that the noise signal has the same amplitude from both antennas, and
then you adjust a phasing control to null out the noise signal. Well, guess,
what? Both for the amplitude matching and for nulling an S-meter showing a
small differences such as 1 dB is highly desirable. While this can
occasionally be done for distant unwanted signals, the main usefulness of
the device is for when the amplitude and phase relationships are constant,
i.e. for local noise sources. Thus there is no QSB to dither the reading
between full S-units - with only full S-units shown you have no idea if you
are 6 dB or 1 dB from the next step. If you don't see a small decrease when
approaching the null, you are likely to turn the knob too fast and miss the
null altogether. My workaround was to turn off AGC and listen for the volume
changes. I deemed the built-in audio level meter to be too slow. To to what
almost any radio would let me do by just watching the S-meter, I had one
button press to turn off the AGC, one shock to my ears, one adjustment to RF
gain, one button press to turn on AGC and one readjustment of RF gain.

A computer program displaying the S-meter output from the K3 is no help in
this situation, as it only sees whole S-units, and with no QSB it won't
bounce between those steps. A panoramic display is probably helpful, and
this experience gives me another reason to get one. However, after I spent
the day using the computer for other work, I usually feel to lazy to turn on
ham radio software just to relax from the computer by doing some some ham
radio. Also, I always do Field Day with a group that lets me bring my own
radio but has no power source to power my laptop. (Logging is done using an
ancient DOS FD logging program, running on a small old laptop to which I
don't have access for installing panoramic software (nor any other software
that might complement the functionality of the K3). 

73,
Erik K7TV


David Cutter wrote:
> 
> Agreed
> 
> 
>> A calibrated S meter could be useful tool in many other ways.
>>
>> - Measuring  field strength and patterns of antennas.
>>
>> - Reporting on things like BPL and other radiated and conducted 
>> measurements that seem to be a daily threat on HF. Just knowing they
>> close 
>> to  S9 plus plus minus 20 db is not a professional way to build an 
>> argument against such pollution in professional circles. Having a 
>> calibrated S meter  and adding something a like calibrated loop with a 
>> known antenna factor would make collecting and surveying potential RF 
>> pollution data very easy. While we don't need 0.1 db accuracy 1 db of 
>> accuracy is easily achieved in SDR radios.
>>
>> http://www.vk1od.net/bpl/QueanbeyanBplTrial2.htm
>>
>> - Using a good S-meter would also be a reliable  way of surveying a 
>> potential new QTH. The data could be used to compare signal noise levels 
>> to the thermal noise floor, or even compare what you are measuring to the 
>> surveyed ITU noise levels on HF.  It would be nice knowing that your 
>> potential new QTH  is in a QRM silent location. It would also be good 
>> comparing noise floors amongst hams for various locations.
>>
>> - It would also be useful knowing how accurate and reliable propagation 
>> programs are on a daily basis since they do predict signal levels.  This 
>> might come in handy if one wanted to build a DSP  based DF system which 
>> relies on ionospheric data.
>>
>> - As a general level meter around the shack, it could even be used as an 
>> accurate power meter.
>>
>> So to me a well calibrated S-meter can take  the place of many expensive 
>> instruments that most hams dont have access to on a daily basis. It is a 
>> very useful tool. When  we use some sort of absolute reference our 
>> understanding of what we are  measuring on a daily basis  increases our 
>> understanding of what we are doing in our hobby.
>>
>> While we on this subject if further work is carried out on the K3's 
>> s-meter  you might as  well follow the IARU's recommendation for S-meters 
>> and make it quasi peak in nature.
>>
>> Besides these days, with the  competition increasing in the new radio 
>> market with radios like the Perseus, ADAT and the newly released cheap 
>> Flexradio models, all which offer a very accurate S-meters as a feature. 
>> It would do no harm to the K3's reputation  having a feature that some 
>> consider desirable, that's marketing not  rocket science.
>>
>>
>> 73
>> Craig
>> 
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