146MHz RD06+RD15 Amp by Robert Swinbank M0DTS
Amplifier RD06HVF1 & RD15HVF1
I found these devices give very good results for low cost when getting started on 2m DATV, and so simple to construct!
They have about 20dB gain each stage, so -10dBm input from the DATV Express gives +30dBm of output power using both devices in series.
There is reasonably good harmonic attenuation, approx -55dBc at 1W output.
The input and output match of these devices is very similar so the layout is the same for both.
The bias is around 4V, 2k2 pot with zener ref – not original design but should be good!
All coils are 8mm inside diameter and 0.9mm wire.
Input and output series caps are 100pf.
RD06 device seems best at a bias level to get 0.4A drain current with no RF.
RD15 device seems best at a bias level to get 1.4A drain current with no RF.
These were found when the power is set to 1W.
Other caps can be variable or fixed, i got good results with the fixed values shown, 20W saturated from the RD15 device and about 7W saturated from the RD06 device.
Tuning the amp by adjusting trimmers or coils for best power at or near saturation usually gives the best linearity, tuning at low power levels for best gain will give much poorer results.
I have not tried to fit both of these devices on one board in a single box yet, it may give stability issues with the high gain but should be possible – someone else can comment there, i’m used to microwave frequencies!
There are some higher power devices in the same range so i would assume they are suitable too, still to test…