|To:||[email protected]blacksheep.org, [email protected]|
|Subject:||Cheap and nasty sources - was LF: DK7FC WSPR bad quality problem|
|From:||Andy Talbot <[email protected]>|
|Date:||Sun, 27 Mar 2016 19:05:53 +0100|
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It is unfortunate these cheap and simple low power solutions have come-about at all. The originators who worked out how to generate a few milliwatts of Rf from very non-purpose designed hardware presumably never anticipated that eh great masses would end up connecting this unsuitable kit to high power amplifiers. I hope they only ever anticipated their being used for very low power uses.
As for the R-PI, that really does look like a bad way of generating narrow band RF. I don't know the details of its internal hardare, but strongly suspect that it uses a jittering Fract-N route to generating arbitrary frequencies. Again, fine for a few milliwats of test signal, but certainly not for amplification to hundreds of milliwatts.
If you want a decent high power source, use a DDS chip or a modern Fract-N synthesizer like the LMX2541. That device has an internal VCO and an output divider that allows it to generate as low as 35MHz - and then any external CMSO divider will allow you to go lower. And they are CLEAN - especially so when divided down to LF / HF
On 27 March 2016 at 18:14, Graham <[email protected]> wrote:
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