>>You are talking about measuring swr with a tuned circuit/flywheel at the
>>cathode. Cathode impedance, this is not. You must measure direct into
>>the cathode? . . One problem with a noise bridge is that the power is
>>in the microwatt range. .
>One thing I want to point out is that I got the idea of using the RX
>noise bridge from the paper that Jim Thomson sent to me. Again that was
>an article by Irvin M. Hoff, W6FFC that was published in the January 1973
>issue of Ham Radio. This article was re-run in the March 1978 issue
>which is where Jim got it from.
>"The easiest and quickest method of measuring input impedance would be to
>use a variable impdeance bridge such as the RX noise bridge."
Easiest and quickest is not to waste your time measuring.
>"When making the impedance measurement the high voltage must be on the
>amplifier, and the meter hooked as close as possible to the place the
>network will be added."
I don't think I would be inclined to connect a Rx noise bridge to the
cathode of 4-1000A with six or seven kV on the anode.
>The article also references some another article:
>"RX Noise Bridge for Accurate Impedance Measurements." by Frank Dotting,
>W6KNU and Robert Hubbs, W6BXI. Ham Radio, February 1977 page 10.
>We shall see how it works!
To save time, build a 40m or 20m pi network with a 25 ohm Xc at the
input. Adjust L1 and C2 for the best match.. Measure the values, scale
them up and down as needed for the other bands. . If the scientific
measurements, do not agree with what makes my exciter happy, "frankly, my
dear, I don't give a damn". .
R. L. Measures, 805-386-3734, AG6K
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