Re: LF: DK7FC's VLF Active Antenna

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

It won't be long before leaded components become unavailable.  Certainly the useful modern ones that actually do teh job that's wanted.   I've compared availability and prices in the Farnell catalogue recently (having just got the almost cubic shaped printed version :-)   and leaded components are just more expensive and less available that SMT equivalent.    And the bulk ordering quantities available on many of them make ordering less than 100 off of some of the more popular ones just a waste of money.   

 

Constructors really will have to start getting used to using SMT devices are their first choice every time.  Start practicing now before you're forced to.

 

Andy

www.g4jnt.com

 

been using SMT components for preference for something like 15 years now.

 

 

2010/12/29 Stefan Schäfer <schaefer@iup.uni-heidelberg.de>

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