GO BEARCATS wrote:
Presumably the LO-Z input, not the HI-Z. Switching
between inputs can have some interesting and maybe
useful effects, the differences varying with frequency.

I use the Lo-Z which is for coax, what are some of the
'interesting and maybe useful effects' Tom?

I think I know what you mean, I've never used the HI-Z,
between the two, which one do you prefer?

The system comprising an antenna and receiver is so complex that there
aren't any hard and fast rules. The impedance characteristics of both vary
with frequency and that of the receiver at any fixed frequency can change as
the receiver is tuned. Thus the impedance match and voltage or power
transfer is all over the map. The RF energy in the vicinity of the antenna
changes with time and all receivers are susceptible to overload from too
much reaching the front end.

Connecting an antenna alternately to the LO-Z and HI-Z input almost always
results in a difference in the desired signal's strength but more
importantly can affect the signal-noise ratio. For example, I found that
with short antennas (say under 1/10 wavelength i.e. under 15-20 ft for the
49 metre band) and the DX-394 that the HI-Z input would give higher signal
readings. But with the strong local MW stations overloading the receiver the
background hash would be much higher. Connecting it to the LO-Z input
results in the antenna-receiver input combination acting as a basic high
pass filter that markedly improves the signal-noise ratio.

The DX-394 has some unique properties that differ between the two antenna
inputs that may not come into play with other radios. Only the LO-Z input
has a 20dB pad and the VHF image filter is probably more effective on this
input, if at all on the HI-Z.

I wrote a couple of articles about these issues that can be found at
http://www.mods.dk/view.php?ModelId=573 and at
http://groups.yahoo.com/group/RADIOS...iles/Mods/ANT/ . In "Options
for the DX-394 Telescoping Whip Antenna", I describe how I adapted the whip
antenna to the LO-Z input with an optional clip to the HI-Z input that
proves necessary for reception of low frequencies and can be a plus or a
minus at mid-frequencies.

Since everyone's situation is different and changing with time, there is
ample opportunity to experiment to find what works best at the time.

73, Tom