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RE: RE: IC-910



John:

To answer your question about the CT-17: it uses the max232CPE chip!

73,
Art N3OY


-----Original Message-----
From: John Beanland [mailto:spectrum.ma.ultranet@rcn.com] 
Sent: Wednesday, June 09, 2004 2:05 AM
To: artg@comcast.net
Cc: terrig@clear.net.nz; cbullis@cbullis.org
Subject: Re: [amsat-bb] RE: IC-910

At 21:11 6/8/04 -0400, you wrote:
>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.
>
	********************************************************
									8
June 2004
	N3OY de G3BVU/W1  BT
	Art,

		Thank you for the above results of your experiments.

	We sent a new Interface Cable to Anchorage yesterday; they will get
it
tomorrow, Wednesday. The cable includes Terrig's mod; however we used (like
you) a 2N3904. I thought Terrig's base resistor (47K) was much too large,
insufficient base drive during saturation, so we fitted a 4.7K resistor to
provide about 1mA of base current into the 2N3904 when the latter is
"bottomed".

	Hopefully we will receive a report from Anchorage in a day or two.

	I've added Charles Bullis, K6HG, to the distribution of reports
pertaining
to this problem. For your info Art, Charles was the person who tracked down
the earlier problem of the IC-910 when it switched the functions of
MAIN/SUB bands in satellite mode. Dave, ZL2AMD, has modified his software
to allow for this ICOM "mistake".

	In closing can you identify the circuit of the CT-17, in particular
the
identity of the transistor that drives the output port (and hence the input
of the 910)?

	73s to all,   de John  G3BVU/W1.
	
	
	Yours truly,

	C.J.Beanland, MSEE, C.Eng., MIEE, MRAeS.
	Sales Manager,
	Spectrum International,Inc.	spectrum@spectrum-intl.com
	P.O. Box 1084,			Tel: (978) 263-2145
	Concord, Mass. 01742.		Fax: (978) 263-7008

----
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