RE: [softrock40] a little Amp
- I'v made coments on DIZ site about just that ... but im doing it to the 10W version ... IRF510N did better than the 5739 .. but im looking for usability to 6 meters ... im going to try RD16HHF1 but not sure to skip the mid stage and run from the 5109 to finals ( to be RD16HHF1 ) ... would be the best option ... its not easy unsoldering 3 trans at the same time .. I have them soldered under the pcb ..
What do you think? Use a rd06hhv in Q4 or by pass it?
Date: Thu, 1 Sep 2011 03:22:13 +0000
Subject: [softrock40] a little Amp
Anyone tried this yet .........
Lots of people are always looking for a simple way to crank the power up a little. I still think one of the best (low buck) small amps out there is the little 5W kit from W8DIZ ....but it needs a little work.
1) It only covers up to 18MHz and that's probably because of the 2SC5739 NPNs used which are not really RF transistors ....just like the IRF510 is not a RF MOSFET. So has anyone tried some of the "good candidate" RF transistors out there like the 2SC2166 (spec'd to 10m) or the 2SC1307 (Spec'd to 6m). Both have the ability to not "pop" with high SWR ....at least not immediately like IRF510s. Don't know how linear they are which was the reason for going to MOSFETs in the first place.
2) I would like a little more power than 5W. Both of the suggsted substitutes have higher power capability. They will require a heatsink .....an old computer processor heatsink looks about right. I would mount the transistors to the heatsink UNDER the board and route the leads UP, that way the pin outs are the same. You will need the little mica insulators since the tab is the Collector.
The above will require the usual switched LPFs on the output and some sort of transceiver type switching for the receiver input.
Something else to look into ............ if that does not work as expected, try RD16HHF1 RF MOSFETs (would require a little more rework).
73 Kees K5BCQ