FW: TopBand: High input intercept devices

[km1h @ juno.com]

On Thu, 9 Apr 1998 19:00:48 +0300  YO3CTK <yo3ctk@alltrom.ro> writes:
>I'd say that one of the best solutions is to use a good old 2N5109 in
>non-dissipative negative feedback circuit (patented by Norton). About 
>25mA
>of collector current yields a +30dBm input IP3 with a very low noise 
>and
>50ohms input and output impedance. This arrangement has been used with 
>great
>success by Rohde&Schwarz in their EK070 VLF/MF/HF communication 
>receiver.
>The amplifier use a specially wound trifilar transformer, which is 
>easy to
>do after careful study of the patent.


Mike, I would love a copy of that circuit...can you point me in the
proper direction?
I have been using the ANZAC patented lossless feedback circuit since
about 1982 which is also around the 2N5109....a great device! I can
supply that circuit if you...or others wish. 

Another great device in that or other designs is the NEC 41632B bipolar.
With a 4GHz Ft it has about a 1-1.5dB NF and IP3 of +15dB  at 8-9 dB of
gain 1-30MHz in the Anzac circuit. The 2N5109 is about 1.8-2dB NF. I have
built -in the preamp in all my TS-940's and 830's and use a rewired DIM
switch to control.  Although rarely used on 160M it really wakes up the
RX on 10-20M.

73  Carl  KM1H


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