Product Review and Short Takes from QST Magazine April 2009 Product Reviews: DC to AC power inverters; Maha MH-C9000 Battery Charger. Short Takes: DX Engineering FCC050-H05-A Feed Line Current Choke Copyright © 2009 by the American Radio Relay League Inc. All rights reserved.
Inverter Types product review DC to AC Power Inverters Reviewed by Howard Robins, W1HSR ARRL Contributing Editor When I became active in the ARRL Amateur Radio Emergency Service (ARES), I realized that I needed to be able to run my station during commercial power outages. A friend, I noticed, lugged an Optima AGM deep-cycle marine battery to field operations.
Cotek ST1500-112 Serial number: n/a Manufacturer’s Specifications Power requirement: 10.5-15.3 V dc. Output voltage: 100/110/120 V ac ±3 %. Max power output (continuous): 1500 W. Waveform: Pure sine wave. Size (HWD): 4.5 × 9.3 × 15.9 inches; weight, 15.4 pounds. Price: $650 (including transfer switch) ARRL Lab Measurements Input current, no load: 1.18 A. Output frequency: 59.9 Hz. Load (W) 49 358 745 1140 1515 Input (V dc) 12.6 12.3 12.0 11.8 11.5 Input (A dc) 5 32 69 111 158 Output (V ac) 121.1 120.
Another PSW type inverter, the Samlex PST-100S-12A is rated for continuous output power of 1000 W and 2000 W surge. Battery connections are made on the rear panel. The front panel has two standard ground fault circuit interrupter (GFCI) ac outlets, an on/off switch and LEDs to indicate power on, overload and over temperature. This inverter provides protection for polarity reversal of dc input, overload, and high temperature. The low voltage alarm activates at 10.7 V dc input with shutdown at 10 V.
XANTREX XPOWER 1750 PLUS The XPower 1750 Plus from Xantrex is an MSW type inverter rated for 1500 W continuous and 3000 W surge. The “1750” in the name is from its rating of 1750 W for 5 minutes. The Owner’s Guide for this unit is a little light on discussion of features. There are two LEDs on the front panel — one for POWER on, the other FAULT. In addition there is a power switch, a 3-digit meter that displays battery voltage, and a multicolor LED bar graph for output power.
Power Inverters and Conducted Emissions Limits Some electronic devices intentionally generate RF but do not intentionally radiate it. For example, RF generated by computers, receivers and switching power supplies is intentional and necessary for such devices to function. This RF, however, is not intended to be radiated as it would be by a transmitter. Under Part 15 of the FCC rules, such devices are defined as unintentional emitters.
particularly demanding application. For this reason, the Lab decided that it would be useful to test the inverters using standard Part 15 procedures and instruments. This testing offers an objective way to compare emission levels among the inverters reviewed and allows direct correlation with other unintentional emitters and the FCC limits. Test Setup The ARRL Lab uses a line impedance stabilization network (LISN) and a calibrated Rohde & Schwarz ESH-3 EMC receiver to measure conducted emissions.
MH-C9000 is capable of other functions as well — functions that are generally not available except on expensive industrial production equipment. Specifications are shown in Table 3. Here’s the rundown of its capabilities. making it usable on most worldwide power mains. The MH-C9000 will also accept 12 V dc from a car or boat system, so it can go on Field Day and emergency events. Charge I especially like this charger’s individual cell charging circuitry.
short takes DX Engineering FCC050-H05-A Feed Line Current Choke Gooch’s Paradox: RF gotta go somewhere. Ideally, all the RF your radio generates is radiated into space by your antenna, minus the losses that occur along the way. Problems arise when some of this radiated RF ends up in troublesome places, like on the outer braid of your coaxial feed line. I had been experimenting with a lowprofile Inverted-L antenna for 160 and 80 meters.
