Topband: KD9SV Preamp with BF-981

[WD8DSB at aol.com]

Tom,
 
The modification you mention for using a BF981 with the KD9SV preamp is as  
follows :
 
Install a 22 ohm resistor between the 100 ohm resistor and  the source of 
the dual gate mosfet.  The 100 ohm resistor is currently  connected to the 
source of the dual gate mosfet and ground, so you need to cut  the trace that 
connects the 100 ohm resistor to the source of the dual gate  mosfet and 
place the 22 ohm resistor across this cut in the trace.
 
When done with the mod you will have a 22 ohm resistor connected to  the 
source of the mosfet, and then a 100 ohm resistor connected to the other  side 
of this 22 ohm resistor and ground (with a 0.1 or 0.05 ufd cap in  parallel 
with the 100 ohm resistor).
 
(The 100 ohm resistor and the 0.1 or 0.05 ufd cap already exist in your  
preamp, you are just adding the 22 ohm resistor as described above).
 
I obtained this info direct from Gary (KD9SV) a few months ago.
 
Don  
 
 
In a message dated 3/5/2011 11:09:53 A.M. Eastern Standard Time,  
thomas.hoeppe at asamnet.de writes:

Hello  Topbanders,

today I forgot to hook the keying line to my KD9SV preamp.  I destroyed the 
OMRON G6A relay, witch bypasses the preamp. It is available in  DL. 
The problem is the 3SK88 transistor. I heard KD9SV is now using BF-981  
with a small modification (cut one trace and add one resistor)

Anyone  knows the details?

TNX in advance!

Tom,  DJ5RE
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