[MAMS] DC-DC boost converter

[Danny Pease]

The only testing  I have done so far is without a load of any kind. For what
it is worth, I did not notice any extra noise on HF, 6 meter, 2 meter or 432
gear and I tuned around a good bit listening for new noise. This was all
done with the unit sitting on the bench, no shielding or bypassing at all.
What it will do under load is yet to be determined. I have not tried
listening at at various output levels either, all my noise testing so far
has been at 24 VDC output. I did run the adjustment pot through the full
range and with 13.4 VDC in I saw 13.1 to 35 VDC output.

Most switching noise I have encountered has the largest effect at lower
frequencies, although I hear many strong signals on 6 meters, but most are
not switching power supply noise. Since this is a microwave group, it is
possible any switching noise would not be an issue.

Danny NG9R


-----Original Message-----
From: mams-bounces at mailman.qth.net [mailto:mams-bounces at mailman.qth.net] On
Behalf Of Dr. Gerald N. Johnson
Sent: Wednesday, October 03, 2012 9:53 AM
To: mams at mailman.qth.net
Subject: Re: [MAMS] DC-DC boost converter

Two critical questions: What's its minimum load? What's its noise output?

Switching supplies are based on some chip doing pulse width modulation. 
A boost converter often stores energy in an inductor with a pulse then lets
the inductive kick supply the load through a rectifier, though it can be a
step up transformer. In either case the control chip usually has a minimum
pulse width of a couple % of the period, and smaller loads get higher
voltage. Many a switching supply has a crowbar on the output and simply
won't get past the first pulse if the load is too small.

Many a switching supply is noisier than a transmitter on an antenna. 
Chinese engineering doesn't seem to care about stray noise either.

73, Jerry, K0CQ

On 10/3/2012 9:37 AM, Zack Widup wrote:
> That's a really good price. I'd consider building my own if they 
> weren't so cheap. I wonder about the quality. Maybe I'll order one, too.
>
> 73, Zack W9SZ
>
>
> On Wed, Oct 3, 2012 at 9:02 AM, Danny Pease<dpease at adams.net>  wrote:
>
>> I picked up a DC-DC boost converter on EBay and it looks like it will 
>> fill the bill for those wanting to run devices that require voltage 
>> higher than
>> 12 volts. The price was very reasonable, $7.39 shipped from China. It 
>> will accept a wide range of input voltage and has an adjustable 
>> output, will handle 150 watts at a max of 10 amps. I have not tried 
>> it out on the air yet so I cannot vouch for how clean it may be. If 
>> you are interested, look at item #280930034367 on EBay.
>>
>> Has anyone else had any experience using these devices?
>>
>> Danny NG9R
>> dpease at adams.net
>>
>>
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