[ARC5] Antenna current meter

[Mike Hanz]

On 10/24/2012 4:32 PM, Ian Wilson wrote:
> Looking at the antenna relay/capacitor box, the meter is labelled something
> like
> 'Antenna Current Indicator'. It is marked 0-10 with a more or less linear
> scale, no
> units. These units could be amperes (1.4A into a 10 ohm radiation resistance
> would be about 20W), but the linear scale is suspicious.
>
> Does anyone know what the RF current vs indication for the unit as a whole
> looks like?

I tried to cover that at http://aafradio.org/flightdeck/I-71A.html - full scale is/around/  4 RF amperes, but obviously you *cannot* interpolate the linear scale.  It's a non-linear function and was not intended as an instrument - only a relative reading as you were tuning up the transmitter.


> Alternatively, does anyone know what the operator's manuals say for indicated
> current with the appropriate per-band dummy load should be (and what series
> resistance said dummy loads present)?

The series resistance is five ohms "non-resistive".  There is a 100pf 
vacuum capacitor that can be clipped in series to simulate an aircraft 
antenna.  I won't reproduce the current data because you can download 
the manuals for that...it depends on frequency and mode, and is all over 
the place.

73,
Mike  KC4TOS