Note
HD-1422 1985-1989 $49.95
HD-1422A. 1989-1991 $49.95
The HD-1422 Antenna Noise Bridge is a very useful, though little understood, device. Valuable for the serious antenna experimenter, it may be of little or no interest to the average operator, and Heath probably didn’t sell many of these.
Unlike an SWR bridge, which indicates how well an antenna is matched to your transmitter, a noise bridge reveals what is causing any mismatch. The HD-1422 is a tone-modulated, broadband noise generator coupled to an impedance bridge. Using your station receiver, the impedance bridge measures the resistive and reactive components of your antenna.
The 1422 may also be used to pre-tune an antenna tuner, to tune quarter wave transmission lines, and to find the value of unknown capacitors and inductors. All in all, a handy device for the serious HF antenna person. Having the instruction book would be extremely helpful in learning to use the HD-1422.
Front panel includes power on/off and pilot light and controls for resistance and reactance. The rear panel has two SO-239 connectors (marked “unknown” and “receiver”), a ground lug, and a standard DC external power connector. The unit can be calibrated using your station receiver. The original is brown while the "A" version is gray. Not common.
References:
Review. QST. Nov 1986, p. 40.
Using a noise bridge. Ham Radio. May 1986, p. 69.
Front panel ranges:
resistance: 0 to 200Ω
capacitance: ±60 pF
Operating frequency range: 1.0 MHz to 30 MHz
Useful frequency range: 1.0 MHz to 100 MHz
Power requirements: one 9-volt battery (NEDA type 1604) or external 9 to 11 VDC power source, 45 mA
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
