[Elecraft] [K3] RE: New K3 User and New Ham

[KC2VNI]

Mike: I don't have any form of power supply. From my brief discussion with the tech over at Elecraft, he recommended the RS-35A from Astron. 
  
In this instance, I did look at the Western Mountain Radio unit you have below. 
  
I wanted to make sure I understand something: that the radio can be supplied from 120VAC from this unit OR you can use it to supply power from an external battery as you mentioned below. 
  
Is this the case? 
   
  

-------- Original Message -------- Subject: Re: [Elecraft] New K3 User and New Ham From: "Mike B-12 [via Elecraft]" <ml-node+4253206-516824144 at n2.nabble.com> Date: Mon, January 04, 2010 9:26 pm To: KC2VNI <steve at smarrano.com> Good evening, Steve.  As for item #2, you'll likely find that even with a 100 AH battery, the voltage will drop rather quickly at 100 watts. And as the voltage drops, the current consumption will rise to keep the output the same, even more rapidly draining the battery.  I would suggest: 1) consider using lower power. You'll likely find that running at 50 watts (or less, particularly on CW or PSK) will net you essentially the same number of QSOs, at far less power consumption. 2) run 2 batteries in parallel (in this case, 12 volt batteries).  That will help keep the voltage up by spreading the load across more than one battery. 3) even if running parallel batteries, consider a battery booster from MFJ or http://stores.tgelectronics.org/StoreFront.bok   I have not tried either, but I think QST did a review of 2 models some time back. By far the easiest (and most common) type of large battery to use is a sealed lead acid.  Technically called Valve-Regulated Lead Acid, but more commonly called "gel cells" or AGM (Absorbed Glass Mat).  While there are slight charging differences between gel & AGMs which need to be observed, for our purposes here either will work the same.  These are NOT automotive batteries, but rather true deep cycle batteries.  Perhaps you already know this, but automotive batteries have many, thin lead plates that give a lot of surface area.  This is great for sudden, short periods of high current draw, like starting your car, but very bad for long-term discharge (like leaving your headlights or radio on).  True deep cycle batteries are essentially the opposite, made with fewer but thicker lead plates, and generally poor at very high current discharges, but great at running smaller loads long term. Some AGM batteries on the market now will work as starting batteries, too, but that's not relevant for our needs. If you're on a tight budget, a car battery will work at low power for a while, but you'll quickly want a better battery.  The batteries labeled as "deep cycle" at the big stores generally are NOT deep cycle - it's just marketing.  You'll likely have to go to a real battery store, though the some of Optima line of batteries are deep cycle, and can be found at Sears, among other shops. The gel- & AGM-style batteries are sealed to the point where you can't add water, but if over-charged will vent gas.  However, with a quality charger, this is a non-issue and these batteries are approved for in-home use (think electric scooters and wheelchairs). This is an example of a quality, American-made AGM battery: http://www.sunxtender.com/   We've used these at work for our remote weather sites for the last 5 years or so, and have been quite happy with them (no financial relation, yada yada yada).  The PVX-1040T size is one we use; it's rated at around 100 AH (at a 20-hour rate), and tend to cost around $230.  Not cheap, eh?  There are less expensive brands out there, typically made in China.  I have zero experience with these. This is a long email (sorry), but food for thought.  There are lots of battery choices out there, but since you've picked the top rig, I thought I'd show you one of the top batteries ;-)  Once you've got your batteries picked out, get a quality charger.  There's no better way to destroy any battery than to cook it (or chronically under-charge it) than with a crappy charger.  I'd even venture to say that if you want to save money on batteries now, put the money towards a good charger - it will outlast at least a few sets of batteries. If you already have a power supply, or simply as another option, West Mountain Radio's Super PWRGate works well ( http://westmountainradio.com/SuperPWRgate.htm ).  It needs a power source, but has a charging circuit and essentially works as an uninterruptable power supply for your rig.  I bought one 3 or 4 years ago, and it's done a great job of maintaining my batteries. 73, Mike KW1ND ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto: [hidden email]  This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html 


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