Hi Stefan.
I have just completed your VLF Active Antenna
except for the 4:1 transformer, considering all my previous correspondence
regarding sound card microphone input impedances being anywhere between 4k ohms
and 10k ohms, are you using this as a step - up or step - down transformer,
and which sound card input are you using mic or line input? I will be using
Winrad 1.32, and was hoping to complete in order to look for Chris G3XIZ today
as his QTH is 20km from my self.
Wishing you good luck with you sub9kHz work in
2011.
73s.
Ken
M0KHW
----- Original Message -----
Sent: Wednesday, December 29, 2010 6:16
PM
Subject: Re: LF: DK7FC's VLF Active
Antenna
Hi Ken,
I have not tested other JFETs so far. Is it
just because of the SMD housing? I don't use a SMD PCB but a "free air"
soldering. So if this is the problem, just solder the FETs legs directly on
the next part, e.g. solder the drain directly on the 390 Ohm resistor.
Attached you find a picture that shows how my current used VLF grabber antenna
looks inside. Don't be shocked ;-)
If you anyway want an alternative,
the J310 or the (2SK170) should be possible. There are some parameters
like the noise and the gain and the input capacitance which are affecting the
performance but this is all not so critical on VLF.
73,
Stefan/DK7FC
Am 29.12.2010 17:58, schrieb Ken:
Stefan.
Could you please recommend an equivalent to to
BF862 which is not Surface Mount for use in this circuit.
73s
Ken
M0KHW
