Paul OH3LWR:

While you definitely need the lowest noise figure and a high gain when
using small magnetic loops, I very much doubt that you are going to
need the strong signal handling capabilities for these antennas. Why
not use a dedicated preamplifier constantly attached to these
antennas, possibly with some protection circuitry to avoid damage when
transmitting through your nearby transmitter antenna ?


The idea is to have one preamp or RF stage for whole range of antennas 160 -10
or 6 m. No outboard boxes, preamps, but one good "in house" adjustable gain
amp. No step or switchable attenuators either. Normal city mortals have high
band noise levels, but when you go to the ocean front, use RX antennas or beam
north on high bands, you need sensitivity and of course high dynamic range for
the other end of the signals spectrum, like operating in Multi/multi
environment.

Thanks for N6NWP article info, I will look it up.

Yuri, K3BU.us

Do you have specific requirements? You may well be able to do fine
with a different, simpler design. I'd submit your requirement is not
for a cascode, but for specific TOI and perhaps harmonic performance
and noise level and input and output impedances.

Cheers,
Tom


Low noise, high dynamic range, strong signal handling.
Again, useable for low signal RX antennas and handling strong in-band signals
like in multi/multi situations, when you want to tune/scan the same band while
transmitting on that band.
Filtering and protection is another story.

Low noise mixer is to follow, with low phase noise synthesizer.

Trying to beat K2 and Orion front ends.

Yuri, K3BU

Do you have specific requirements? You may well be able to do fine
with a different, simpler design. I'd submit your requirement is not
for a cascode, but for specific TOI and perhaps harmonic performance
and noise level and input and output impedances.

Cheers,
Tom


Low noise, high dynamic range, strong signal handling.
Again, useable for low signal RX antennas and handling strong in-band signals
like in multi/multi situations, when you want to tune/scan the same band while
transmitting on that band.
Filtering and protection is another story.

Low noise mixer is to follow, with low phase noise synthesizer.

Trying to beat K2 and Orion front ends.

Yuri, K3BU

On 4 Apr 2004 12:07:18 -0700, (Tom Bruhns) wrote:



Do you have specific requirements? You may well be able to do fine
with a different, simpler design. I'd submit your requirement is not
for a cascode, but for specific TOI and perhaps harmonic performance
and noise level and input and output impedances.

Cheers,
Tom


I really suspect that it is outlined an amplifier which it is not
expereinced whether it is needed or not, I believe it is no need for
extra amplification below 15 or 20MHz, and since the frame antenna is
relatively narrow banded it is no need for particularly good IP3
characteristics on any frequencies

Somebody once mentioned that a transistor with 50mA collector current
equalled a valve amplifier with 5mA anode current in respect of IP3,
wonder such is likely to be true? Suggested valve is 6761 with
gm=50mmho

73
Jan-Martin
LA8AK
http://home.online.no/~la8ak/e.htm
----
Jan-Martin, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/

On 4 Apr 2004 12:07:18 -0700, (Tom Bruhns) wrote:



Do you have specific requirements? You may well be able to do fine
with a different, simpler design. I'd submit your requirement is not
for a cascode, but for specific TOI and perhaps harmonic performance
and noise level and input and output impedances.

Cheers,
Tom


I really suspect that it is outlined an amplifier which it is not
expereinced whether it is needed or not, I believe it is no need for
extra amplification below 15 or 20MHz, and since the frame antenna is
relatively narrow banded it is no need for particularly good IP3
characteristics on any frequencies

Somebody once mentioned that a transistor with 50mA collector current
equalled a valve amplifier with 5mA anode current in respect of IP3,
wonder such is likely to be true? Suggested valve is 6761 with
gm=50mmho

73
Jan-Martin
LA8AK
http://home.online.no/~la8ak/e.htm
----
Jan-Martin, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/