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Re: [Amps] HLA-150 information page

To: "Ken Bessler" <>, <>
Subject: Re: [Amps] HLA-150 information page
From: "Tom W8JI" <>
Date: Wed, 28 Jun 2006 15:42:11 -0400
List-post: <>
> With all the discussion going on about this amp, I thought 
> I'd post my
> review that I put on the net several months ago:
> Ken

Hi Ken,

I hope you don't take offense at this, but.......some 
comments about your review:

1.) That amp is not a switching mode amplifier, and not 
being switch mode it can't possibly have 80% efficiency.You 
must have had a serious metering or math error.

2.)  I looked at the circuit, and there is not special about 
it at all. All that stuff about "flywheels" is just 
nonsense. It is a regular push-pull amplifier with forward 
bias, it is simply a traditional class AB amplifier driving 
a regular old lowpass filter.

3.) With an unresolved metering problem we can't be assured 
the transfer function data is reliable.

4.) On the air reports are next to meaningless. People can't 
"hear" the distortion of a class C amp on frequency unless 
it is terribly bad. We don't really know how clean the amp 
is by anything you wrote.

Things like this trouble me. It is VERY easy to get an amp 
type accepted if it complies with rules. It is inexpensive. 
It is also very plain that amp would never pass FCC TA 
requirements, so that is almost certainly why they didn't 
apply for TA and sell legally. E-Ham is absolutely correct, 
it is an illegal amp.

When I see a large company selling things into the market 
via the backdoor and reviews that very clearly have serious 
mistakes helping steer their products into use, I don't get 
a warm feeling. I think we are heading down the wrong path.

I'd be happy to measure and post the actual IM3 and IM5 
specs and efficiency of that amplifier, measured with up to 
date currently certified test gear, at no cost to you. If it 
looks good, we should all endorse it. As it is right now, 
very little in your review makes sense. There is no such 
thing a "flywheel" that cures IM distortion, the efficiency 
can't possibly be 80% since that is beyond the theoretical 
limit of a perfect lossless AB amplifier and nearly twice 
what a solid state 12V amp will typically do, and there is 
nothing reliable that tells us it passes harmonic tests or 
is linear.

73 Tom 

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