[ARC5] Ant. Series Matching Caps- I Just Don't Get It.

[Bill Cromwell]

Hi Ian,

It can be a royal pain to setup everything to measure the power output 
with the scope and followed by the arithmetic. "lessee now, pi 
gazzints...". I do a compromise and check the voltmeter, wattmeter, 
frequency counter, etc every once in a while. If I get inconsistent 
results it might be time for another spot check. Sometimes intermittent 
cables can cause hair pulling, too. I'm sure Dave already knows about 
"that".

73,

Bill  KU8H

On 01/15/2015 10:14 AM, Ian Wilson wrote:
> Dave - a couple of thoughts:
>
> 1. when doing this sort of test, the focus tends to be on the hot end of
>      the transmitter - but poor RF grounding can easily introduce a stray
>      ohm or two of loss, and move the results all over the place
>
> 2. you say "nearly identically" - but well, or poorly in terms of watts of
>      output compared to last time?
>
> 3. measuring gear can go bad over time. I find when measuring power
>      that it helps to check with a scope in addition to relying on the power
>      meter (this also finds embarrassing things such as transmitting a
>      harmonic of what you intended)
>
> I have found a small number of capacitors (all ceramic, IIRC) that seem
> to soak up power when used to match ARC-5 TX outputs. Others have
> some variation in efficiency but nothing dramatic.
>
> 73, ian K3IMW
>
>