[R-390] sensitivity, product detector, etc

[William A Kulze]

Hi Mark, thanks for your thoughts. In playing with this a little more I
have noticed that the RF gain as I had set it was lower than optimum gain.
I think it has helped me with finding a good setting for the IF gain
adjust, though. As far as a big preselector goes, my thoughts were that I
have heard a lot of discussion on the subject of R390 audio quality and
SSB detection. I have been using the audio out via the diode load mod for
a while now, and it results in much better sound. I get that same sound
now through the PC and the same hi-fi amp, but I also get a full
assortment of demodulation methods and a nice spectrum display. The R390
family is legendary for pulling in signals and I am using every bit of
that. I just leave the bandwidth at 16kc and I can tune through the band
with a nice old-fashioned analog knob while adding a few "modern" bells
and whistles. Believe me, nothing will ever replace the R390a in my book,
but I can still have a little fun with this, right?

As far as G303i command line switches, if you go to winradio.com and click
on G303i in the middle of the home page, then select 3rd party developer
info from the bottom of the G303i page, you should see the link for
switches at the bottom of the page. The only one I need is /sd which stops
the demod from loading on application startup. This lets you use any demod
app that uses a 12kHz I/Q IF fed to the sound card. This opens a lot of
choices, but that's for another group all together.

My nearest MW station of any power is about 70 miles. I have a couple of
5kw stations within 30-40 miles. The antenna is about 60ft 12 AWG THHN
from house to tree about 20 - 25 ft up. I see the signals show up in 19,
20 and 39 meter bands. If I click the attenuator on the g303, the signals
go away, but so do some weak ones that are really there. Using the loops
I've made, I don't see a problem. I use the winradio 9:1 match for the
wire ant. I may try making a tuner and using that instead.

Regards,

Bill


> Well, first, the RF Gain also controls the IF Gain, too. So what you are
doing is shutting off the RF Amp, and the first, second, and third IF
amps, then cranking up the gain on the third IF Amp. Then when you
adjust the RF Gain up, you are increasing the gain on all those stages.
Don't know how that would affect the noise floor of the receiver. One
good thing is that the R-390 is acting as one honking big preselector.
>
> Did not know about the command line switches on the G303I. That would be
handy. And this is the first I heard about problems of overloading in
the MW band. Are you close to broadcasters?
>