August 14, 1973

HM-102						Bulletin No:

Watt Meter/SWR Bridge				HM-102-1



Possible Shorts Due To Mounting Hardware

The circuit board mounting bolt near R4 -[100K] is extremely close to the adjacent foil.  There is a very good possibility this foil could be 

accidentally grounded.

By eliminating the lockwasher and substituting the G-32X1/4” flat head bolt with a 6-32 X ¼” round head bolt, [PN 250-31], the problem is 

eliminated.



December 23, 1974

HM-102						Bulletin No:

Watt Meter/SWR Bridge				HM-102-2



			     Service Notes



Problems originate because a 50 ohm load is not used for calibration; even though the kit manual says to use a 50 ohm load, customers use 

antennas and even light bulbs.  A clue that this is what is being done wrong is an inablility to null during SWR adjustments.  Another clue is 

abnormally high power output readings.

If a customer cannot null during SWR adjustment, and he is using ther proper load, suggest replacing the toroid coil and D-1 through D-3 

which seems to be the magic cure-all for 90% of all the problems encountered with this unit.

C-4 has been some problem, but this capacitor has been changed to a husky one [PN 31-57].  The watt meter portion of the unit will not 

adjust properly until the SWR balance has been done properly and a good null is obtained.  The indication here is R-6 not adjusting properly.  

Again, the toroid coil and D-1 through D-3 is suspect.

Some customers will ask about use of 75 ohm lines.  The SWR will be higher, but collar readings will be within specs.  It can be recalibrated 

and used with a reasonable degree of accuracy.

A common complaint is the high and low power readings not agreeing.  Explain to the customer the specifications on the meter accuracy 

which is plus or minus 10% of full scale.

March 7, 1980

HM-102						Bulletin No:

Watt Meter/SWR Bridge				HM-102-3



		           	  C4 Destroyed



++++Information not yet available++++

Thats everything I hold up to 1989 that covers the HM-102.  Enjoy!