Heathkit HM-102 Meter Alignment

[Rankin A. (Army) Curtis]

George,

Here's what the book says:
--------------------------------------------------------------

POWER METER

This section of the Manual contains two calibration procedures:  one for
calibrating the RF Power Meter on the 40-meter band, and one for calibrating the
Meter on any one of the other bands.

For maximum accuracy, the Meter should be calibrated on the 40-meter band, even
if it is going to be used on the other bands. Therefore, if your transmitter
will tune to the 40-meter band, use the "Normal Calibration" procedure to
calibrate your Meter. However, if your transmitter will not tune to the 40-meter
band, use the "Calibration on Other Bands" procedure. Since the meter readings
are more accurate in the upper-half of the meter scale, it is desirable to use a
transmitter that is capable of delivering at least 100 watts of output power for
either calibration procedure.

NORMAL CALIBRATION

(  )  Turn the FUNCTION switch to 200.

(  )  Adjust the transmitter output to 100 watts.

(  )  Complete the calibration as follows:

    1.  Set the CALIBRATE switch on the remote chassis to CAL and note the meter
reading.

    2.  Now set the CALIBRATE switch to NORM.

    3.  Adjust POWER CALIBRATE control R6 with the alignment tool so the meter
reads the same as noted in step 1.

    4.  Repeat steps 1 through 3 until the meter readings for the CAL and NORM
switch positions are the same.

Leave the CALIBRATE switch in the NORM position.

This completes the calibration of your RF Power Meter.

------------------------------------------------------------

The above procedure assumes that you have the RF Power Meter connected between a
transmitter and a 50 ohm non-inductive dummy load, of course.

To calibrate the SWR meter portion of the instrument, simply adjust C4 for the
best null while reading SWR, and at 100 watts into the dummy load.

To calibrate the RF Power meter portion on other than 40 meters, you will need
the ability to accurately measure the RF voltage across the dummy load, and then
calculate the equivalent RF power.

Keep in mind that RF wattmeters are notorious for being less than highly
accurate. The HM-102 is rated at 10% accuracy, but it is not stated at what
frequency that applies.

Hope this helps.

Army - AE5P
Nacogdoches, the oldest town in Texas

George Gleim wrote:

> Greetings Green Guys,
>
> Could anyone out there give me the 'Readers Digest' version (if there is
> one...) of the alignment procedure for a HM-102?  Or perhaps email me
> the page?  Just purchased a very nice one and I'd like to know how
> accurate it is.  Right now I have three Heathkit meters and they all
> show different readings :)
>
> Thanks very much in advance!
>
> George
>
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