[Elecraft] P3TXMON Question?

[Wes (N7WS)]

Maybe "really precise" is a stretch when you're using scalar instrumentation.

Considering the money we put into rigs and antennas, the ~$500 price of the 
DG8SAQ Vector Network Analyzer is affordable.

I can remember the days when I had to have some precision attenuation 
measurements made on a piece of equipment and it took an airplane ride to a 
sister facility where an HP8410 network analyzer resided in a 
temperature-controlled clean room.

Later I was able to purchase one of the first HP8510s ($250K) for my work lab. 
It was rack-mounted and weighed a couple of hundred pounds. At that time NBS 
(NIST) wouldn't even certify 3.5mm (SMA) standards.  BTW, a set of test cables 
was >$3K.  Imagine trying to convince Management that these were throw away 
items after so many connect-disconnect cycles.

Now I have the VNWA 3 analyzer in my home lab.  I can hold it in my hand and 
within its frequency range, it is every bit as good as the HP and the software 
is a whole lot more powerful.

Radio-wise, we live in magical times.

Wes  N7WS

On 8/21/2015 11:19 PM, Edward R Cole wrote:
>
> But for really precise SWR I use directional couplers and calibrated open, 
> short and 50-ohm terms.  They are never subjected to over +10 dBm.  Return 
> loss is what is actually measured and one can use a conversion chart to 
> determine SWR.  If I had the money then a VNA is the optimum instrument.  But 
> the average ham does not need that.