[time-nuts] About HP10544A

Esa Heikkinen scifiscifi at sci.fi
Sun Mar 8 00:10:00 UTC 2009

 > Its probably better to increase the emitter current to 40mA or
 > so and place 47 ohms between the emitter and the output coupling
 > capacitor a and accept the resultant +7dBm output.
 > The transistor dissipation will increase and it may be better to
 > substitute something like a 2N5943, 2N3866, 2N 5109, BFW16A
 > or similar.

I don't have those 2N types but after some digging found 2N2219A. 
Changed that and 47 ohms from emitter to the ground. I run it first with 
6 volts, then with 9 volts and then with 12 volts but have to stop with 
uncomplete sweep because it become very hot.

Increasing the current does help with amplifier linearity but not so 
much. However the spectrum looks little bit better now but it's still 
out of spec:


> About the only way to achieve the distortion you observe is if the
> capacitance of the wire connecting your emitter follower to the 10544A
> output is too large (around 50pF or more).

It's about 30 cm. long microwave coax taken out from some RF stuff 
(maybe old cellphone). It's measured capacitance (at the other end free) 
is 36,2 pF.

I'll send the picture later if still needed..


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