Fig. I i Assembly of the elevated-feed antennaI
Patj/ Crupp KAILR 73 Magazine Statt
The TET SQ-22 Antenna
— walking the dog with a two-meter quad
fronMoback ratio. Without problems. The parts were a test range, these figures carefully marked and are impossible to either packed, and the quality of confirm or deny, although materials used is higher they do seem slightly opti- than average. Assembled mistic. Nevertheless, with exactly according to in-the antenna mounted six structions, the center fre-feet atop a house and quency of resonance was turned with a small TV-type about 146 MHz, a reason-rotator, gain and F/B ratio able compromise. Since I appear to be excellent rarefy operate FM below
Assembly presented no 146 MHz, I retuned the antenna for a slightly higher center frequency,
After several months of operation, the SQ-22 has given no cause for complaint, I use it constantly for accessing repeaters and simplex operation and have never wished for more gain. If you're in the market for an antenna for two-meter FM and want something a little beyond the ordinary, you might want to look into the SQ-22. For the truly adventurous, an eight-element Swiss quad for two meters is available from TET, as well as Swiss quads for several other bands from 20 meters to 432 MHz.
For more information, contact TFT USA, 425 Highland Parkway, Norman OK 73069L Reader Service num-N1BE) with the TET SQ-22 two-meter antenna. her 476. ■
The HB9CV Swiss quad designs have been around for quite a while, but they have seen relatively little commercial exploitation in the USA. Available and quite popular in Japan for several years, they are now offered here by TET USA of Norman, Oklahoma,
ter antenna is a vertically-polarized Swtss quad antenna that follows the HB9CV design It consists of two two-element assemblies in a phased configuration, with all four elements driven, The antenna is very compact, yet the gain and front-to-back ratio figures claimed are impressive —16 dB forward gain and 20 dB
Clenn Malme WbOIF 9337 Cotham Street Downey CA 90241
Newcomer to Nicads?
— you'll get a charge out of this informative overview
The following covers some of the more common problems encountered by users of nicad batteries, ' he last section of this article explains some of the technical aspects of the nicad cell
Virtually all problems involving batteries come with complaints like; "Battery life too short"; "Won't hold a charge"; or perhaps, "Battery too weak " Sometimes there is a real problem — and sometimes the battery is not getting what it must to do a good job.
Here are some practical tips:
1. Fully charge the battery. Some chargers have a NORMAL-TRICKLE switch, In the TRICKLE position, it would take 24 to 60 hours to futSy charge a dead battery, On NORMAL, it would take 12 to 14 hours, Nicad batteries can be charged continuously at the NORMAL rate with absolutely no damage to the batteries whatsoever. Leaving the radio on while charging will cause the charging rate to be longer.
2. Don't over-discharge the batteries Turn OFF the radio when the batteries become low (the SQUELCH control usually won't silence the radio).
3. Never insert batteries backwards. This will almost certainly ruin something.
4. Inspect your batteries occasionally for any indication of rust or t orrosion A white, powdery deposit around the rubber seal at the positve end of the cell or an oily discoloration on the label may be the first sign of an upcoming failure.
5. If your batteries have a short life, check the battery-charging system. Two simple checks will be enough to find the problem. First, check to see if the charger is putting out enough current. Second, check to see if the radio draws too much current. If the charger and radio are OK and you are allowing enough time on charge, then the battery is probably at fault.
What is a Nicad Battery?
The nicad attery is two or more nic ad ceils connected togt- ier. The nicad cell is called a secondary (storage) cell and is used to store electrical energy until needed. !t may be recharged many times during its life. The cell may be described electrically by its voltage and capacity.
Cell voltage is determined solely by the materials from which the cell is made. Nickel and cadmium in a potassium-hydroxide electroiyte produce a cell with a nominal voltage of 1 2 volts. There is only a relatively small change in cell voltage from fully-charged to discharged conditions Refer to the section on battery-testing (following) for cell voltage-measuring techniques. Cell voltage vanes from 1.4 volts when just charged to 1,0 volts, at which point it is considered discharged. Nominal cell voltage is 1.2 volts since the cell is very near 1,2 volts for most of the time it \s in use, (Of course, if you have a 10-cell battery, the battery voltage is nominally 12
Cell capacity is defined as the maximum current the cell will deliver continuously for one hour. This capacity is given by the battery manufacturer in milliam-pere-hours (mAh) for small cells, and Ampere-hours (Ah) for large cells. Capacity is determined by the size of the cell. For example, an AA-size cell is rated around 350 to 500 mAh and a D-size cell is rated at 2.0 to 4.09 Ah. A very important figure associated with cell capacity is the one-hour discharge ¡rate (C) which is numerically equal to the capacity. For example, for a quantity, C, we can discuss the charge and discharge of nicad cells conveniently without concern for actual cell capacity.
Battery operation should be at temperatures between minus 20 and plus 40 degrees C. They may, however, be stored indefinitely at temperatures between minus 60 and plus 60 degrees C. Most batteries will self-discharge at rates dependent upon the storage temperature involved. At 0° C, discharge amounts to 90% in 60 days. At 20° C, it is 50% in about 55 days, and at 50° C it is 50% in about 20 days.
Fully discharged, open-circuit *1.2 V
Fully charged, open-circuit M .27 V
FuHy charged, charging at 0,1 C 1.45 V
Freshly charged, begin discharging at C 1,4 V
Fully discharged, discharging at C t.O V
'These voltages are reached slowly as the celt is allowed to stand for a time.
Table 1. Cell Voltages af 20°C
Generally, batteries may be expected to last several years under normal use A minimum of 300 cycles of complete charge and discharge is to be expected. If only a partial (say, 20%) discharge is used, the life may extend to 5000 cycles. However, if the battery is partially discharged continuously, it should be periodically deep discharged to realize its full capacity.
Most batteries are normally discharged (in-circuit) at rates less than C and charged at a rate of 01 C If a trickle charge option is available, the charge rate is 001 to 005 C Most bat teries may be left on NORMAL (0.1 C) charge for indefinite periods without damage. At the normal rate, a completely discharged battery will recharge in
12-14 hours. Less time is re quired for partially discharged batteries. Charge rates above 0.1 tend to overheat the cell and cause damage. Special "RapidCharge" cells are required for fast-charging applications.
Table 1 (showing cell voltages) may be of help in understanding battery function during charge and discharge.
The battery, charger, and radio constitute a small system which is one end of a communication link, When this system fails, testing each element is necessary to determine the proper correction. Based on experience, the charger is the most likely to fail, followed by the battery and then the radio. However, due to ease of testing, test the charger and radio first.
For the 12-volt, hand-held radio chargers, connect a milliammeter ustng a D'Ar-sonval movement (such as: Simpson 260 or Triplett 63G)h capable of measuring 55 mA, in series with a 240-0hm, 1-Watt resistor. Connect the meter-resistor combination across each and every set of charging contacts for a 12-volt battery. Observe correct polar ity, The charger current should be 45-55 mill ¡amperes.
Consult the appropriate data sheet for the radio under test, Measure all applicable maximum current drain on; full squelch receive, full volume receive, and transmit. Readings should not exceed spec maximums.
A quick battery check would be: Charge at normal (0.1 C) rate for 15-30 minutes, Measure battery or cell voltage. Less then 1,2 volts per cell (12.0 volts for a 10-cell battery) indicates possible defective cells.
For a more complete battery test for a hand held radio battery with 10 AA ce!lsr fully charge the battery for 12*14 hours at the normal (0.1 C) rate. Connect a 27-Ohm, 10-Watt resistor across the battery and monitor the time required to discharge the battery to 1.1 volts per cell The time should be close to 60 minutes.
This test will vary according to ambient temperatures. The time will run short if the ambient temperature is much over 25 degrees C, or if started with the battery more than slightly warm to the touch
The nickel-cadmium batteries will perform excellently if used within their limitations. Poor performance usually results when the limits are exceeded.®
supply and standby and power switches, as well as provisions for using external headphones. Another source of memory backup power is the BC-1 power adapter. We suspect that a functional equivalent of the BC-1 could be homebrewed for much less than the $20 list price One accessory that Kenwood does not offer but in our experience is helpful for weak signal work is a receiver preamplifier, A quality unit can really enhance SSB operation without adding to the noise figure,
We liked the compatibility that Kenwood built into the TR-9000. The power cord and touchtone connector are the same as those used with the TR-7600
and the 7625. The microphone is identical to that used with the TR-7800 and can be pressed into service with Kenwood's VS-230 remote digital vfo One exception to this area is the rather unusual connector used for the backup power supply.
The TR-9000 offers a tremendous number of features for a reasonable if not downright inexpensive price. If you want to take a crack at two-meter SSB and CW operation and still have a radio that allows you to chew the rag with the gang on the local repeater, you'll find a flexible answer in the TR-9000.
For further information, contact Trio-Kenwood Communications, lnc.f 7111 West Walnut Si reef, Comp-ton CA 90220. ■
outs to signal priority, lockout, delay, auxiliary, and channel number. The right-hand display may be manually toggled between digital frequency display and alpha readout,
A Closer Look
A glance inside the custom diecast metal cabinet reveals the complexity of the circuit, but shows the precision of professional design.
Frequency increments searched and programmable vary with the band plan procedure On low and high band FM, channel spacing is 5 kHz, on aircraft band 25 kHz, and on UHF 12.5 kHz.
An automatic squelch circuit may be called up to respond to any signal level which produces 20 dB SI NAD (S + N/N). This is handy for most listening re quirements which do not require constant juggling of the squeli h sensiti\ ity right at threshold.
Frequencv coverage was actually somewhat greater in our evaluation unit than advertised. We pn> grammed 30.0-50.995,118.0136.995, 144.0-174.005( and 420.45-512,9875 MHz. This allowed reception of the first megahertz of the six-meter band (FM demodulation only) and a few beeps and whistles from NASA's weather satellites!
As with its predecessor, the advanced BG300, the BG350 has a non volatile memory —no batteries to change.
The BC-350 is advertised for $599,95. For more information, contact Electra Company, PO Box 29243, Cumberland IN 46229, Reader Service number 460. ■
John Edwards Kt2U 78-56 86th Street GfendaleNY 11385
"Don't you ever run out of material foryour column?" isa question that often crosses your FUN! editor's desk. The answer, quite horv esily, is ;:no.' Amateur radio is a subject so Full of history and interesting bits of information that, quite likely, the well will never run dry. After all, new ham tacts are being created every day.
Take our monthly crossword puzzle Each month a new topic; each month a new puzzle. Oh, occasionally we may repeat a word or clue here and there, but, on the whole, each month's puzzte isentire-ly different. And we're never really stuck for material
Do you know where the world's first crossword was printed? Why, In the FUN! column, of course! No, not this FUN!, but one carried in the December 21,1913, New York World. It's nice to be carrying on a tradition,
Now, what has all this to do with this month's topic, emergency communications? Absolutely nothing, Ws just that we occasionally like to digress,
ELEMENT 1—CROSSWORD PUZZLE (Illustration 1}
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