Topband: Help for Preamplifier

ik2bcp - Guido Tedeschi guido.ted at
Sat Mar 25 07:53:46 EST 2006

Hi Petr,
    sorry for the delay, but I wanted to publish a small web page with few
pictures to show you my "ugly" construction...
Look at:
Using a 2N5109, with 12V, the current is about 50mA and a small TO5 heatsink
is enough.
I did not measure the NF and IP3, only gain (about 20dB on low bands) and
maximum output signal before compression (about 23dBm, if I remember well).
We use it with one wavelenght beverages, standard type and layed over ground
(BOG), and we used third order Cauer bandpass filters, between antenna and
preamplifier, in our multi-op contest station.
This preamplifier was also used daily, last winter, on topband band by
73 de Guido, ik2bcp

----- Original Message ----- 
From: "Petr Ouředník" <indians at>
To: "ik2bcp - Guido Tedeschi" <guido.ted at>
Cc: <topband at>
Sent: Friday, March 24, 2006 9:12 PM
Subject: Re: Topband: Help for Preamplifier


regarding the W7IUV preamp I am also interesting in the performance of that
design cause:
as I checked the schematic >

- seems that expected current should be more than 100mA
- will be neccessary to use good heatsink
- it does not impact the noise figure of preamps if it will work with so
high current (Pc more than 1W?)

Do You have good experience with noise figure in practice?

Thank You,

Petr, OK1RP

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