On Wed, 2007-09-26 at 23:02 -0500, Bob McGraw - K4TAX wrote:
> The Paragon does have an overload issue derived from nearby BC stations
> {50KW at 30 miles or less} when used with long antennas for the 100 KHz to
> 1.7 MHz band. Long antennas as in 1/2 wave for 0.5 MHz or so. (900 to 1500
> ft} The Paragon II does not have this problem as the front end design was
> changed as stated to prevent overload from BC stations. Yes, there is some
> sacrifice with performance below 1.7 MHz. There is also some different
> switching configuration for the attenuator on the input between the Paragon
> and Paragon II.
>
> 73
> Bob, K4TAX
>
Perhaps the Paragons would benefit from the combination of a low pass
filter and a preamp when listening to LF. Many editions of the ARRL
Handbook have included such a low pass filter and likely a preamp with
larger coils and coupling capacitors designed for use with a 160 meter
Beverage antenna would serve well.
I know when using a double balanced mixer and LO for listening at LF (as
an up converter) that without that low pass filter, I get mostly
broadcast signals.
The MMIC MAV06 or equivalent would make a decent preamp. 3 dB NF and 12
dB gain with an output P1 of +17 dBm... Would need larger coupling
capacitors than used for HF, and its good to at least 1 GHz for other
projects. Two coupling capacitors, a bias resistor, a power supply
bypass and the 4 terminal MMIC. Hard to be simpler.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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