[TenTec] Monitor (was moniter)

n4lq@iglou.com n4lq@iglou.com
Thu, 25 Apr 2002 14:17:55 -0400

Speaking of CW monitoring....One of the best is the TT 13x0 series QRP 
rig which actually plays the beat note through the audio system instead 
a normal sidetone. The FT-1000MP has a similar system, enabling one to 
monitor the actual keying and you can hear yourself in the Heath HW-16 if 
you rip out the neon bulb. 
For SSB, the TS-870 must be like that Kachina in that it monitors the 
digital stage and you can hear your voice response change as you adjust 
the tx audio slope.

N4LQ Steve

-----Original Message-----
From: "George, W5YR" <w5yr@att.net>
To: Larry B <K1zw@webtv.net>
Date: Thu, 25 Apr 2002 12:29:36 -0500
Subject: Re: [TenTec] Moniter

> Possibly, Larry, but probably not likely.
> Monitors can range from simple audio taps off the modulating audio
> signal;
> to separate monitor systems which usually function to downconvert the
> r-f
> transmit signal to baseband and present the output through a separate
> monitor audio amplifier system ; to - in the case of digital rigs - DA
> converters and audio systems which emulate the second approach above. 
> Usually the first type is a fair indication of what you are putting
> into
> the rig but no assurance of what is coming out. The second type can be
> a
> very good replica of your transmitted signal depending upon how good
> the
> monitor audio system is. The third type can range from fair to
> excellent,
> usually depending upon the word-length of the DA converter and the
> quality
> of the following audio stages.
> My IC-765 is an example of the second type and it gives a fair idea of
> what
> your transmitted audio sounds like. The transmit IF signal is taken to
> baseband with the BFO signal into a special monitor mixer stage and
> then
> the resulting audio is amplified and mixed into the main audio output
> system.
> My Kachina digital radio uses a separate DA converter for the monitor
> system on the transmit digital data stream at the 40 KHz DSP-processing
> level and takes the output to drive the monitor audio system. Early
> Kachina
> models used only an 8-bit DA for the monitor channel and the results
> were
> very poor. An update greatly improved the results with a 16-bit DA
> converter and a better audio system.
> My Icom 756PRO uses a digital version of the approach taken with the
> 765.
> The main DA 24-bit output from the DSP processing feeds not only the
> transmit IF channel - starting at 36 KHz and then mixing up through the
> higher IF's until the output frequency is reached - but also feeds a
> separate digital mixer which takes the 36 KHz digital data stream
> signal
> back to baseband audio where it is digitally filtered and added into
> the
> main audio output channel.
> Of the three, the PRO provides the best indication of the actual sound
> and
> quality of the transmitted audio signal. I have verified this by
> observing
> the output signals in the time domain with a scope, in the frequency
> domain
> with SpectroGram and by careful listening over a quality outboard audio
> system.
> As most "audio experts" will tell you, however, do not rely upon your
> rig's
> monitor if you *really* want to hear what you sound like. Use an
> external
> receiver with a fairly wide bandpass and ensure that it is not
> overdriven
> and that it is tuned as accurately as possible to you transmitted
> frequency. You will still hear only what the monitor receiver passes
> through its IF and audio stages so it is not a perfect solution, but it
> probably is representative of what most of your listeners are hearing.
> I don't know what system your Jupiter uses, but the block diagram will
> probably give you a few clues and pointers to the circuit diagrams if
> you
> want to dig into the specific circuitry.
> Funny, but in the old days of AM and CW, we seldom gave much thought to
> "monitoring" the actual quality and sound of our transmitted signals,
> other
> than soliciting on-air reports, as we still do. I used a WW2 surplus
> BC-221
> frequency meter to monitor my CW signal both to measure the actual
> transmitted frequency (!) and to hear the tone of the signal.
> 73/72/oo, George W5YR - the Yellow Rose of Texas         
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
> Amateur Radio W5YR, in the 56th year and it just keeps getting better!
> QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
> Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437
> Larry B wrote:
> > 
> > Just been enjoying the moniter feature of the Jupiter. Kinda nice to
> > hear ones own voice. I  assume that the other party in the qso hears
> > just what I hear when using the moniter feature ? If there was a
> problem
> > in the ssb audio one could hear it using the moniter feature ?
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