[ARC5] Re: [Milsurplus] SCR-274-N Transmitter Dial Accuracy

[J Forster]

Something else just occurred to me. The tuning of the transmitter could very well be
adversely affected by reflections from the conducting hanger surfaces.

Some time ago, I was playing with the antenna from an AN/APN-1 Radio Altimeter. I had
it mounted on a roughly 2 foot square sheet of aluminum and connected to an HP 8505A
VNA (Vector Network Analyzer) that displays gain and phase of the reflection
coefficient in real time. Anyway, the display wandered all over the place as I moved
about the room, even 5 feet away.

Roughly scaling by 100 for the difference in frequency (400:4) between the APN-1 and an
ARC-5, that says that objects even several hundred feet away can affect the VSWR.

Best,
-John

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