LF: SMT PCB version of the PA0RDT MiniWhip

[Andy Talbot <andy.g4jnt@gmail.com>]

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BUT ...

I've made a PCB for a slightly modified PA0RDT miniwhip amplifier.  This became necessary after my Procomm active whip died - it had started generating noticeable IMPs from local MF broadcast stations then the gain dropped considerably.  I wanted to use the same whip and mounting hardware, so had to produce a small PCB to fit inside the exiting housing.

Changes to the circuit :

: 2N5109 replaced with BFG591

: Additional 27R added in series with the output feed from BFG591 emitter, to give more certainty of stability in the event of a capacitive load.

: Input 100nF capacitor added to DC isolate the whip from the gate, since mine has exposed metalwork.  10M resistor as a static bleed on the, now-isolated, whip

: 10k bias resistor reduced to 8k2 in view of the higher hFe of the BFG591

: 220R emitter resistor replaced by two 430R in parallel (mainly because the BFG591 has two emitter connections, and the other one looked lonely, but also helps with power dissipation).

All details are in the rsgb-lf-group@groups.io  files section under a folder called "MiniWhip SMT" 

But if you don't subscribe, you can't see them !

Andy

www.g4jnt.com