The Potomac Analog FIM is no longer available, nor are the parts to
repair them and calibration service is no longer available. The new
meters are expensive digital units. But in broadcast we do not use them
to determine power but rather coverage usually when directional systems
On 2/21/12 1:05 PM, Jack/W6NF wrote:
> On 2/21/2012 8:26 AM, Joe Subich, W4TV wrote:
>> > On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote:
>> > The important thing is to have a way to assure that when someone
>> > measured the same field at the same point with the same type of
>> > measurement device they would get the same measurement result.
>> > That would allow us to compare measurements between different
>> > people even if we did not know the absolute field strength value.
>> I think simple, repeatable and accurate are a difficult triad. What
>> you are talking about is an accurate Field Intensity Meter (FIM) and
>> getting stable calibrations with home constructed equipment is not
>> going to be easy - let along easy to duplicate. The closest solution
>> is to use standard antennas (not simple whips) and calibrate them
>> against broadcast signals at known locations and known field strengths.
>> This will still require separate antennas for 160 and 630 meters and
>> separate calibration sources on the appropriate ends of the standard
>> broadcast band (due to the antennas).
>> ... Joe, W4TV
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
> It's been many years since I have had to make any AM broadcast field
> measurements. I don't recall if the Potomac Instruments, or other, FIMs
> go much below 550kHz.
UR RST IS ... ... ..9 QSB QSB - hw? BK