[RFI] An inverter question or two.

[Dale]

Ken,

If I may, I'd like to suggest a non-inverter approach, since your output power requirements are quite modest:

How about an audio amplifier approach?  There are numerous low power (5 to 30 watt or so) PA amplifiers around (new or used on eBay or at hamfests) that could do the job.  The key is the fact that amps intended for PA use often have actual output transformers so that they can provide industry standard "constant voltage output" at the 25 or 70.7 volt levels.  If you feed a nice sine wave into the amp, you will get a nice sine wave out as long as you do not drive the amp into clipping.  You can then do what you want by using the 70.7 volt output tap.

An alternative is if you have only a conventional audio amp intended for mobile use (13.8 VDC operation), drive it with a nice sine wave and connect the output into a tube audio output transformer that is connected backwards.  That is, drive the 4 or 8 ohm speaker winding of the old xfmr and take the output off the plate (primary) side winding.

I would not be suggesting either approach if you needed 100 watts or more, but for the few watts you need, a true inverter is almost overkill.  You are correct, of course, in wanting to avoid use of square wave or other non-sinusoid wave methods. 

73, Dale
WA9ENA        


-----Original Message-----
>From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
>Sent: Mar 21, 2014 12:16 PM
>To: RFI <rfi at contesting.com>
>Subject: [RFI] An inverter question or two.
>
>Well, it looks like I didn't address my original question to the list correctly, so 
>here goes again.
>
>Does anyone here know of a small 12VDC to 110VAC inverter that is 1) NOT 
>noisy, RF wise, and 2) outputs a real sine wave? 
>
>It would not have to output more than 100 watts.
>
>If not, I'll have to design and build my own, or use a dynamotor and following 
>circuitry to get what I need: 75 VDC at a few mA and ~2.0 VDC at 900 mA.
>
>Kenneth G. Gordon W7EKB
>
>"Courage is being scared to death but saddling up anyway."--- John   Wayne
>
>_______________________________________________
>RFI mailing list
>RFI at contesting.com
>http://lists.contesting.com/mailman/listinfo/rfi