[hpsdr] ability to amplify pennywhistle (much) beyond 17W?

[ct1izu]

17W is more than enough drive to satisfy any legal output for just about anywhere in the world. Its all about what type of linear you want to drive and how you develope the drive power. 

The 50W your Elmer's talk about only applies to a Triode linear amp,  if its a Tetrode then 50W will drive it silly. I can drive a pair of 4CX250B,s on 144Mhz to over 500W with just 2 watts of drive.

If you want to use some of the typical Commercial 1kw linears then your  best way forward is a combination of  a little Attenuation on Pennywhistle and one of Granbergs Motorola AN designs from CCL in Ohio,  to give you a 100W output from the HPSDR set up. 

If you are not the typical appliance operator then the 17W could easily drive a home brew  tetrode amp using 4CX1500 or the RU equivalent.

The set up here uses Pen to drive a pair of 2SC1969 to around 8-9W then into a a Modified AN762 amp  http://www.communication-concepts.com/appnotes/AN762Sharp300.pdf  with a pair of SD106 transistors.
My external linear uses a pair of GI7b to give around 1KW.

The System has been fully operational since 31 January  2009 and I have logged over 2,500 contacts with possibly as many reapeats and regulars that dont appear in the log. The Rig averages an 8 Hour on time 7/12 so when people do get operational with Alex they can look fwd to a well enginered set up.

Shel CT1IZU


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  I just came back from my digital group showing what I have been assembling here and the biggest answer I got was pretty much "that's a lot of money for a qrp rig".  This would be my second radio beyond a 5W triband HT, so 17W did seem like a lot in comparison, but they're saying that it takes a minimum of 50W to drive an amplifier and 100W is the minimum target in order to get good transmission on HT.  Plus my wanting to explore heterodyning into higher frequencies cutting into the signal power and this starts to feel a bit on the weak side.

  So... we have Pennywhistle that does 17W.  Other than linking to a second radio, can I get some suggestions as how to amplify the output from this thing?

  Erik KE7YOA




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