[Amps] Checking for IMD

[Martin AA6E]

Oops, the PSKmeter does NOT use the sound card -- it has its own simple 
A/D converter which connects to a serial port.
--Martin

Martin AA6E wrote:
> Why not directly detect the output RF with a linear rectifier / filter? 
>
> Also, why not use closely spaced tones (20-30 Hz) to make things easier 
> on the sound card?
>
> This is basically what the PSKmeter 
> (http://www.ssiserver.com/info/pskmeter/) does.  It's very cheap.  The 
> question is whether the IMD numbers it delivers are useful or 
> believable.  Probably you need a higher quality detector if you want to 
> go down to < -30 dB reliably.
>
> Agreed that what you are measuring is the exciter plus amp, but at least 
> you get an upper limit.  And, what we care about is what gets radiated, 
> not just what the amp does.
>
> 73 Martin AA6E
>