Is is valid to test a thermocouple-type RF Ammeter using low
frequency (say 60 Hz) current? I did so and got quite
reasonable results. Hey, current is current, right?

I have three different thermocouple-type RF Ammeters, with
FS ranges of 1.5, 2.0 and 3.0 RF Amps that I wanted to test.
The 2 Amp meter has an external thermocouple (16 mV DC for 2.0 RF Amps)
and the other two have internal thermocouples.

I hooked them all up in series, and also in series with a
Fluke digital AC Ammeter, fed them from 6.3 VAC through a suitable
dropping resistor. All readings agreed within a few percent at various
currents.

Can I now assume that these meters will also function correctly at RF
(i.e. 3 - 30 MHz)?

Thanks.

-Al, W2ADS

On Tue, 22 Aug 2006 04:07:49 GMT, Al Schapira
wrote:

Is is valid to test a thermocouple-type RF Ammeter using low
frequency (say 60 Hz) current? I did so and got quite
reasonable results. Hey, current is current, right?

It is somewhat easier to measure the RMS value of DC current than
mains AC current. It may be worth considering a DC calibration.


I have three different thermocouple-type RF Ammeters, with
FS ranges of 1.5, 2.0 and 3.0 RF Amps that I wanted to test.
The 2 Amp meter has an external thermocouple (16 mV DC for 2.0 RF Amps)
and the other two have internal thermocouples.

I hooked them all up in series, and also in series with a
Fluke digital AC Ammeter, fed them from 6.3 VAC through a suitable
dropping resistor. All readings agreed within a few percent at various
currents.

Can I now assume that these meters will also function correctly at RF
(i.e. 3 - 30 MHz)?

Thanks.

-Al, W2ADS
--

Yup, it's a good bet, Al...

denny / k8do

In article
,
Al Schapira wrote:

Is is valid to test a thermocouple-type RF Ammeter using low
frequency (say 60 Hz) current? I did so and got quite
reasonable results. Hey, current is current, right?

I have three different thermocouple-type RF Ammeters, with
FS ranges of 1.5, 2.0 and 3.0 RF Amps that I wanted to test.
The 2 Amp meter has an external thermocouple (16 mV DC for 2.0 RF Amps)
and the other two have internal thermocouples.

I hooked them all up in series, and also in series with a
Fluke digital AC Ammeter, fed them from 6.3 VAC through a suitable
dropping resistor. All readings agreed within a few percent at various
currents.

Can I now assume that these meters will also function correctly at RF
(i.e. 3 - 30 MHz)?

Thanks.

-Al, W2ADS

Usually done with a calirated DC supply, but Thermal is Thermal
and mostly those meters aren't any better than 2% anyway.....

Bruce in alaska AL7AQ
--
add a 2 before @

Thanks to all who responded.
-Al