#ubitx Power output improvement mods - my results :( #ubitx

Bo Barry <wn4ghv@...>
 

Liking to tinker, I installed very cheap tiny socket PINS (cheap sockets were hard to find) in place for the 6 3904s near the final.
I stumbled upon some 2N2369A transistors on the web. Here my results  (don't get excited)
Ver 4 ubitx

Band  Power output
80 14 watts
40   8
20  13
15  7
10  2    

The results with the 2369As WAS IDENTICAL!!!
The 3904 has a TYPICAL Ft of 300Mhz    and hfe 100-400  power dissipation of 625mW or 1.5W (both figures on datasheet)
The 2369 has a MINIMUM Ft of 500Mhz   and hfe 40-120   power dissipation of 360mW
NOW,  I realize I did not think this out fully.
I had memories of the 3904 as audio frequency devices and the 2369 was advertised as high frequency
I saw the higher Ft and nice metal enclosure (=better heat dissipation)  and fell for them.
A cheap way to learn a bit,

Off to Google and comments in our forums for some ideas.
Why is the power output bump on 2o meters?  One would expect a diminishing value as frequency goes up.
I'll be happy with a nice stable 10 watts across the bands. 

Aren't these little ubitx's more fun than Heathkits from days of old?
73, Bo W4GHv since '54     (I put that because I enjoy thinking BACK and am HOPING to make it to the next sunspot peak!)

Join BITX20@groups.io to automatically receive all group messages.