|[AMRadio] Ranger Audio|
brett.gazdzinski at verizonbusiness.com
Wed Nov 15 08:21:14 EST 2006
I think there were different D104 mic's, some
had a crystal cartage, others had a ceramic one?
The crystal ones have a REAL high impedance, and want
to look into a 2 to 5 meg resistor to ground at the grid.
I also found the mic cord critical, I tried to replace mine,
as it was on the short side, I only added a few feet more, of
quality mike cable, but the audio sounded nasty, and I went
back to the oem cord.
Its real tricky to get a good frequency response out of such
a high impedance, without getting a lot of hum.
If you open up the transmitter audio, it will allow
the passage of the 60 and 120 cycle hum coming from the
I run the mic amp filaments off DC, which eliminates the hum.
I just add a diode in series with the filament, and an
electrolytic cap. The size of the cap sets the voltage,
the bigger the cap, the more voltage. I just experiment
to get around 6 volts.
The DC running the filaments does not have to be pure,
the rough filtering seems enough to eliminate the hum.
I run a 5 meg to ground on all the D104 rigs.
With the audio opened up, and DC filament, and
some feedback from the secondary of the mod iron
to a low level speech amp stage, it can sound very
nice and smooth, and I like the D104 feel.
Plugging a D104 into any stock rig usually ends
up sounding like a really cheap telephone....
I never had one, but I have been told the D104's
with the amp built in are no good...
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Jack Schmidling
> Sent: Tuesday, November 14, 2006 11:03 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: [AMRadio] Ranger Audio
> So I get my new D104 yesterday and spend a few hours removing the
> un-needed junk from it and fire up for the NoonTime Forum
> expecting all
> sorts of kudos and no one can hear me. One guy that could said it
> sounded tinny and crummy.
> So I switch to the Kenwood and they all say wonderful.
> I went of over the whole mic again, plugs, wires, grounds and fixed a
> few things and converted it into a boom mic. I make another
> contact and
> he says tinny but could be his receiver... nice guy. He
> suggests a few
> caps to check so back to the bench with it.
> After looking around, I find that the mic wire goes directly to the
> grid, no resistor divider and no input cap. I now see what
> that strange
> mess at the end of the shielded wire is... what is left of a
> 1m resistor.
> I replace all this stuff and it still sounds crummy. Then I find that
> R22 is missing in the cathode circuit of the output side of the first
> audio. I replace this and it still sounds crummy.
> To establish "crummy" I set the mic near a nice sounding
> radio and set
> up a shortwave receiver in an adjacent room to listen to
> while loading
> up a light bulb.
> In all cases, the Kenwood with the handheld dynamic mic sounds better.
> The only thing (I have said this many times) that I see left as a
> possible problem is C59a/b. These were resistors when I
> started working
> on it. I replaced these with 47uf and 67uf caps as that was
> all I had
> left at the required WV. They are supposed to be 15mf.
> I am not sure just what these do so the question is... could
> these cause
> a lack of lows in the audio?
> If not, any other ideas?
> PHOTO OF THE WEEK: http://schmidling.com/pow.htm
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