> Does anyone know if the drag can be adjusted on the main tuning knob? The
knob has a skirt, and looks identical to the knob on my 302 tuning pod, but
I can't seem to move it relative to the main knob.
Yes, mine has adjustable drag.
>There are several audio outputs available on the back panel J8. I finally
found a pinout in one drawing (figure 3-4 on page 3-5), but nowhere else in
the text. There is a mono (pin 2) out and ground (pin 1). I assume that this
is the "normal" unbalanced audio (line out). There are also balanced outputs
(Line A- A CT, and Line A+, Line B-, B CT and Line B+). I understand the -
and + and assume that the CT means center tap. Can these outputs be
connected to an unbalanced input, such as a computer sound card or a pair of
amplified speakers? There is a DC coupled audio. What does that mean? What
would that be used for?
Good questions. I would not attempt to try and interface the balanced audio
output of the RX-340 into an unbalanced device. (However, if you do, you
will need to ground one side of the transformer *unless* CT is at ground).
The balanced output comes from an audio transformer, not an active device.
Although the frequency rersponse of the transformer is quite good, it is not
quite as good as the unbalanced outputs. I have measured the frequency
response of the RX-340 using SpectraPlus FFT software. The low end response
from the AC-coupled unbalanced output is good down to 20 Hz. The DC-coupled
output is good to...DC. Yes, really. The audio quality from the RX-340 is
near audiophile grade and you haven't lived until you've listened to the
RX-340's synchronous AM mode set at a DSP filter setting between 10 and 16
kHz....or to the Hi-Fi SSB user's group on 14.178 MHz in the 6 kHz SSB
receive setting.
So, what do you do with these three audio outputs? Unless you have a
compelling reason to use the balanced output connection (e.g., direct
interface into pro-audio equipment at 0 dBm into 600-ohms), I would only
use the DC and AC coupled outputs.
In my configuration, I send the DC-coupled audio into my PC sound card for
audio FFT measurements. I take the AC-coupled output and send it to my
Marantz 1030 Stereo Console Amplifier. Keep in mind that the AC and
DC-coupled outputs are nominal 0 dBv (0dBV = 1V)and this is much to great
for interfacing into a sound card or stereo amplifer where the levels are
traditionally set at -10 dBV as the consumer IHF reference. A simple "L"
pad comprised of two resistors installed in the "D" shell connector works
fine and does not degrade the audio performance.
> Lastly, are the grounds on pins 1 and 9 of J8 the same?
Yes, as I recall. Also, several I.F. and DSP BNC connectors are available
at the RX-340's rear panel. I send the I.F. sample (post DSP filter) to
channel A on a dual-trace scope. Scope channel B goes to my Bird RF sample.
I can be engaged in a QSK QSO while simultaneously watching the CW waveform
of my station and the other's....simply amazing.
-Paul, W9AC
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