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RE: IC-910

Terrig et al:

I just tried the transistor mod again. I used a 27K resistor from pin17 to
the base of the 2n3904, emitter grounded, collector to pin 15 and center
conductor of cable. The high voltage on the scope is 4.0V. The low pulses
appear to be very close to zero - certainly within a mv of zero. I can't
resolve the scope trace better than that.

I fired up the software and it is indeed happy with the mod. The radio is
responding and no error message appears. But, the behavior is as I described
before. Only the sub-band is being controlled. The main band never changes.

On the suggestion from a friend that perhaps the rig would be more tolerant
at 1200 baud, I tested all three methods at 1200 baud: 1.) with a TTL hookup
(no transistor mod) on channel 2; 2). with RS-232 to my CT-17 using channel
1, and 3). with the transistor mod on channel 2.

In ALL CASES, the software has ceased to report the radio is off, and is
controlling the sub-band frequency, but it is not updating the main band
frequency at all. If I push the M/S button on the radio to swap the main and
sub-band frequencies, the uplink and downlink frequencies are swapped, and
whichever is in the sub-band is being updated as the computer display

In thinking about my original report that the TTL port would not control the
IC-910 at all, I can only conclude that I was not consistent enough in
resetting the radio, the UT2000, and the software all at the same time. If
one of the above was not in the proper reset state, I can see where it might
report the error. So, let me accept mea culpa on that one.

The good news is that it's working, though not perfectly. Let's see if we
can figure out the software problem with the main band.

Art N3OY  

-----Original Message-----
From: Terrig [mailto:terrig@clear.net.nz] 
Sent: Monday, June 07, 2004 11:26 PM
To: artg@comcast.net
Subject: Re: IC-910

Hi Art,

After you have carried out the "MOD" make sure the relevant jumper inside
the Uni_Trac box is changed from "Y"aesu to "K"enwood ONLY on the TX
channel, the RX channel will still be in the "Y" position.
I don't have a 2N3904 to try but note from my data book a Hfe <100, so that
should be ok.
If you scope the end of the 3.5mm plug (not connected to rig) it should have
a voltage near +5 if the Jumper is in the correct position (K), in the (Y)
position it should clamp this plug voltage to near 0v this test without the
software running.  This would be an easy way to confirm the High (5v) and
Low (0v) levels of the waveform.. a meter could also be used as the levels
are only changed when the jumper changes position. If your new (low) is say
0.3v after this mod you could experiment by lowering the value of its base
resistor while observing the (low) voltage , John has tried 4k7 but time
will tell.

It is interesting to find out from you that the CT-17 has a (low) of 0.6v,
the Uni_Trac measured at this end produces a low of < 0.7v so they are not
far apart, however as I mentioned in my earlier message the IC-910 circuit
would seem to be more sensitive to having too high a Low voltage... does
that make sense !!
You mention a RS-232 protocol analyser, this is more at home in the +/- 10v
Glad to hear that your rig is partially happy !!! now we just have to work
on the rest of it.. Hi.

Sorry  the Sno: means nothing to me.



----- Original Message ----- 
From: "Art Goldman" <artg@comcast.net>
To: "'Terrig'" <terrig@clear.net.nz>
Sent: Tuesday, June 08, 2004 2:03 PM
Subject: RE: IC-910

> Terrig:
> This gets weirder and weirder.
> I wired up the interface but the voltages on the scope didn't seem
> It looked to me like the Rx level wasn't high enough. I used a 2N3904 and
> 47k as you suggested. Nevertheless, it didn't work software-wise.
> So I went back to the original wiring, and connected a scope to a spare
> output on the CT-17. Using port 1 RS-232 output to the CT-17. the idle
> voltage at Rx was 4.4V. On Tx pulses the voltage dropped to 0.6V.
> I connected my port 2 cable again, and made sure the jumper was for Yaesu.
> The voltages matched the CT17 voltages exactly. I was editing config files
> and restarting the program, when it suddenly stopped giving me the IC-910
> error, and the radio started responding -- to a point. It was updating the
> sub-band, but not the main band.
> I guess I should go back and retry the transistor mod just to be sure. Not
> tonight. Tomorrow.
> I have a protocol analyzer. It is set up for RS-232 but I wonder if it's
> sensitive enough to work at TTL? It might be a way to decode the data
> stream.
> In the meantime, I just can't explain why all of a sudden it's partially
> happy. Any ideas on that? I know someone mentioned there was a problem
> main band vs. sub-band at one time.
> Oh, my serial number is 01984. I don't know if that makes it recent or
> 73,
> Art
> -----Original Message-----
> From: Terrig [mailto:terrig@clear.net.nz]
> Sent: Monday, June 07, 2004 4:49 PM
> To: artg@comcast.net
> Subject: Re: IC-910
> Hi Art,
> Many thanks for your offer, it is much appreciated.
> John Beanland is also going to modify a cable and send it up to Alaska for
> testing, but if you would like to try the "mod" that would be great.
> To save typing ( read lazy) I have cut and pasted my correspondence to
> below.
> ********
> I don't know if my idea will provide the answer, but need someone with one
> of these problem rigs to test my idea out. It does require some slight
> change to the DB25 connector end of the radio cable.
> If you want to pass on my experiment please feel free, but please remember
> this is an experiment and I will NOT accept any liability for what someone
> else may do to their equipment.
> My idea ( after some bench testing with mock-ups of the Icom 910 internal
> "Remote" circuit) is to place an additional small signal NPN transistor
> (BC547, 2n2222 etc...) and a resistor within the DB25 housing... Do you
> room??
> The wiring would be as follows for TTL channel 2:
> The TTL rx (15) to go to center core of cable to Remote connector (no
> change).
> The TTL tx (17) to go to the Base pin of the additional transistor via a
> resistor.
> The Emitter of this transistor to go to the Ground pin as used for the
> screen of the above co-axial cable.
> The Collector of this transistor to go to the rx pin (15).
> With this "MOD" in place the TTL internal jumper for channel 2 TX will
> changing to the "K" position.
> The same procedure may be used for TTL channel 1 (using the appropriate
> pins) if required.
> As so many Icom IC-910 rigs are not having a problem, I would envisage
> mod only being required on rare occasions.
> What this "Mod" does is pull down the data LOW "TX" signal from Uni_Trac
> the Icom rig closer to 0V thereby switching the "Remote" RX circuit in the
> icom more fully.  This later Icom "Remote" circuit would appear to be more
> sensitive to its received data not going to near 0v.  This is my opinion
> based on tests carried out on the mini circuits I have made up.
> As mentioned earlier this is only an experiment and may not be the answer
> the problems the 2 Icom rigs are having, it is just an avenue worth
> exploring and I make NO claims for the efficacy of the above "Mod".
> ***************
> and John had a question about the value of the base resistor.
> ***************
> The current drawn from the Icom 910 is about 130 micro amps and adding the
> 1k RX pull-up resistor in the Uni_Trac ,we get a total collector current
> just over 5 m/a.  this in theory would give a base current for this
> transistor of about 50 micro amps if it has a HFE of 100 so my thinking
> 47k should do the job and ensure the transistor is fully turned on.  It
> worked very well on my test jig with over a 100k base resistor, but the
> transistor Hfe was greater than 100. I do not have to hand a 2222 to test
> it's Hfe.
> ----- Original Message ----- 
> From: "Art Goldman" <artg@comcast.net>
> To: "'Terrig'" <terrig@clear.net.nz>
> Sent: Tuesday, June 08, 2004 8:11 AM
> Subject: RE: IC-910
> > Terrig:
> >
> > I'd be happy to help. Tell me what changes I need to make. I can try it
> > tonight.
> >
> > 73,
> > Art
> >
> > -----Original Message-----
> > From: Terrig [mailto:terrig@clear.net.nz]
> > Sent: Sunday, June 06, 2004 9:21 PM
> > To: N3OY@amsat.org
> > Cc: John Beanland; Dave Lamont
> > Subject: IC-910
> >
> > Hi Art,
> >
> > Have been following the 910 discussions with interest.
> > I manufacture the UT_2003 units here in Napier New Zealand.
> >
> > Have been looking into the problems relating to Uni_Trac communicating
> with
> > some Icom IC-910 radio's.
> >
> > On downloading manuals for the IC-910 from the net and comparing the
> > "Remote" interface with earlier Icom "Remote" inputs note quite a
> difference
> > in the  way the 1wire bus is detected.
> >
> > Have built up models of each "Remote" radio interface for comparison,
> > models work with the Uni_Trac box but note that the IC-910 Remote
> interface
> > is much more sensitive to the "Low" level of signal it receives compared
> to
> > Icom's earlier design.
> >
> > I have been working on a possible cure and was wondering if you are able
> to
> > help (as you have a Icom IC-910 rig), it basically involves the addition
> of
> > 2 small components being soldered inside the DB25 shell case of the
> Uni_Trac
> > to radio cable assembly.
> >
> > Please let me know if you are able to help?
> >
> > Many thanks
> > Terrig Evans    ZL2TJX
> > E T Electronics
> > 16 Davidson Ave
> > NAPIER  4001
> > New Zealand
> >
> >
> >
> >

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