I have some interesting info to share with other engineering minded hams. I
have long been plagued by the problem of trying to make accurate measurments
at high power levels. A simple example is the calibration of a wattmeter. I
have never seen a device on the market which fills the bill for this need,
especially at a decent price. So I have finally taken the time time and
effort to do it myself.
I just ran off the final phase and amplitude plots of the first finished
model of a new type of attenuator, which produces 70 db atten. +/- .5 db and
+/-3 degrees phase shift across the band from 2-30 MHz. It also works at
30-150MHZ with a small but known error in amplitude/phase. I have built it up
to emulate the same form factor as a typical inline precision attenuator(
e.g. HP,Weinschel,etc.) with an N-male input and BNC-female 50 ohm output. It
is not a true attenuator - that is a power attenuator. It is a voltage
attenuator which minimally loads the measured node but produces an accurate
voltage output. For example, 1kW at the input connector results in -10dbm
into 50 ohms at the output, which is a nice fit for analyzers, vector
voltmeters, etc. 100 watt transmitters come out at -20dbm, etc. It is
capacitively coupled and dissipates essentially no heat.
The construction is too complicated for normal do-it-yourselfers, with the
key element being a specially designed miniature high-voltage coaxial
capacitor. I am considering marketing it sometime later this year (if and
when I get caught up with all current business.) Meanwhile, I would like to
build up a small batch of them for friends,who can also give me some feedback
on the finished unit.I do not want to go into any overtly commercial
overtures here, as I believe in keeping our hobby as uncommercial as is
feasible. My market for this device would more likely center on the
industrial RF world.
If you are interested, contact me directly and I will discuss in more detail.
I will not be at Dayton personally, but I may make arrangements to send a
working model with a friend of mine, who can show it to interested users. If
that becomes QRV, I will post it on here on Thursday.
Eric von Valtier K8LV
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