Discussion in 'Computers, Hardware, and Operating Systems' started by KK6FYE, Sep 15, 2020.
Can anyone tell what charger would work to charge Comet CAA500 mk2 ant. analyzer??
What kind of battery does it use? Removable? Was it designed to use rechargeable batteries?
Here is the basic info: https://www.eham.net/reviews/view-product?id=12539 Has two different operators talking about: 1. A little known problem: The battery cover must be replaced for use. 2. Rechargeable batteries, size AA ( Penlite, larger type 1.5V nominal ). Note that today there are several varieties of rechargeable cells: NiCD, NiMH, Li-ion, etc. The big problem with many of the devices which use rechargeable batteries is knowing which technologies are compatible. Of the types available, the Nickel Cadmium cells are most likely to be good for a higher voltage upon initial charge. Remember that most Alkaline cells ( non-rechargeable ) put out 1.55 or so until partially discharged. Nickel-Cadmium (NiCD) cells are available in various capacities in that AA size, and will do pretty close to that. The really cheap ones for solar landscape light use have pretty limited capacity. One example is rated 1.2VDC and only 300mAh, made by Jiaweh(TM/R/etc."Yards and Beyond(R)". A more suitable battery is 1.2VDC 700mAh by Chicago Electric Power Systems(TM/R). If you then go to NiMH ( "Nickel Metal Hydrate ") technology, at 1.2 VDC and 2200 mAh is the Thunderbolt(R) cell. Some NiCD chargers are unsuitable for high-capacity cells of newer chemistries. They can literally cause heating, melted plastic was the result in one case that I remember from my own experience. So it is best to read the manual to discover what rechargeable cells the device is supposed to work with.
The shorter answer: For both AA and AAA cells, if you do not mind moving the batteries and want to charge them in an external charger capable of working with Ni-MH, Ni-CD, and Li-ion batteries: EBL (R) Technologies model 18650-BC1 or 18650/14500/1 PR20200617 should take care of your needs, two cells at a time. The output is listed for 1.2V at 500+/-50mA for two cells of either Ni-CD or Ni-MH, and would also accomodate just one slot with a single cell. In addition, it will also charge the following Lithium-ion cells ( auto-detect ) 4.2V at 500mA for two: 26650, 22650, 18650, 17670, 18490, 17550, 16340(RCR123), 14500, 10440, etc. More details may be available from KB5MRP ( Bruce Gaskamp ) at Kobs Electronics Inc., firstname.lastname@example.org, or (979) 836-4005. They are an independent Radio Shack(R) dealer not closed as a company store. I have no financial interest in their store nor R.S./Tandy Corporation(TM/R/Etc.)- yet once worked as a seasonal employee in Memphis. Others may be able to advise you about chargers that work with the internal battery compartment of your Comet CAA500 Mk2 analyzer.
According to some sources: https://cometantenna.com/amateur-radio/swr-meters-analyzers/comet-ant-analyzer/, The D.C. cable should have come with the analyzer. It should be wired center positive, and connected to a D.C. power supply capable of providing the 6 cells with 250mA minimum. Further, the voltage should be between 8 and 16 volts- they remind folks that this must not exceed 16 volts. In the user manual cma-caa500markii_at.pdf, it indicates that NiMH rechargeables are suitable ( thus I would not suggest using other technology rechargeables ). The display will be unstable if the battery voltage is low ( and according to others, maybe if the cover is removed ). Be sure that you use the 'disable charging' switch inside the battery cover if you are using alkaline batteries, shown on page 2 of that manual, control #13. Page 5 shows that 12-14 V.D.C. is preferable, in order for the battery status indicator to show "fully green" after around 14 hours. Charging at 11 volts or less would increase the charge time. One good example of a suitable power supply would be the B&K model 1610, set to under 14 volts. There are less expensive alternatives, which may or may not have voltage & current limiting adjustments and both voltage and current indicating meters.
See the attached file- Theoretically, this should work & save some money.
OK, my original question has NOT been answered. WHAT batteries are originally supplied OR recommended?
NiCD cells are almost "unobtainium," partly because of low capacity (typically 600-700 mAH MAX in AA size.) and MOSTLY because of toxicity due to the Cadmium content. They have been replaced (99.44% of the time) by NiMH cells, which are available in the same AA size (as well as other sizes.) If a "wall wart" type trickle charger meant (originally) for NiCd cells , it will often charge NiMH cells, BUT... since the NiMH cells will (usually) have a much higher capacity, it WILL take longer to fully charge them; an "overnight" trickle charger for NiCd cells, with a suggested 14 hour charge time, WILL take 3-4 DAYS (maybe even longer) to charge a NiMH cell, with a typical mAH rating of 1800-2400 mAH. So-called "fast chargers" (e.g., 2-3 hours for NiCd cells) must be used with caution; they may NOT be appropriate for NiMH cells at the fast charge rate., and the cells, charger or both can be damaged. Only use a fast charger intended for use with NiMH cells, or NiMH AND NiCd cells. Lithium cells REQUIRE a specific type of charger, and should NEVER, EVER be used with a simple charger meant for NiCd or NiMH cells. If the analyzer has specific cells suggested, use THEM. Not necessarily the exact same brand, but the same size and chemistry. And never, EVER try to recharge alkaline cells! (And if there IS a switch to select alkaline vs rechargeable, be SURE to make the correct selection before connecting a charger.
In Post #5, I mentioned that NiMH cells ( around 1.2V times the number of size AA cells ) are shown in the user manual. Six cells times 1.2V plus the regulator drop. Maximum applied external D.C. voltage is 16 for the internal regulator, no A.C. should have been applied externally. As stated previously, 250mA current minimum was suggested by the manufacturer. In post #4, I suggested that if the cells were to be removed for each use- an external charger capable of all three types might be used- one that 'auto-detects' the type of cell. In the case of 6 batteries, that would be 3 'batches'. Hence post #6. I fully agree with all that you have said in post #7, with the exception of NiCD cell availability. Unfortunately, there is a very inexpensive tool 'brick and mortar' store which sells "Chicago Electric Power Systems" cells. By the way- I may never again purchase a battery charger made by the folks whose name sounds like laughing. As the previous owner of a Yaesu FT-51r, I purchased some of their cells- then their charger, then their 'cups' so that the contacts of the batteries would fit the charger. Upon returning melted-plastic battery assemblies to the dealer, I discovered that their new charger had temperature sensors with magnets attached above each cell. That was an "Ah-Hah" moment.
See if you can locate a 'wall wart' ( Class 2 ) or other power supply capable of supply as follows for him: Somewhere between 12 and 14 volts ( 11 too little, too slow; 16 too much- A.C. ripple could be a factor ), with an output of no less than 250mA per the maker. According to Comet, the analyzer in question has a switch inside for six Alkaline ( no charging ) or six NiMH batteries. Now if price is not an object, find a power supply similar to the B & K 1610 in that it can run the same specifications, and has: controls for both voltage and current limiting- plus meters and LEDs to observe the resultant supply. For extra credit: get the full specification on the 'coaxial' plug which is supposed to be polarized center positive. It may be 3.5MM or 2.5MM. If all of this is too much trouble- read post #5. Reminder- this must be D.C., the regulator in the device does not tolerate an A.C. supply- center positive.
How is an AC supply "Center Positive?"
BTW, with barrel (coaxial) power connectors, BOTH the inner (center) conductor diameter AND the outer conductor size are important, not just the outer conductor size. And yes, polarity absolutely MUST be observer with DC connections. Getting it wrong often allows an unacceptable amount of smoke to be released.