X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Sender: To: lml Date: Sun, 10 Dec 2006 14:30:20 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 5.1.3) with ESMTP id 1661207 for lml@lancaironline.net; Sun, 10 Dec 2006 14:18:43 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.8; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m27.mx.aol.com (mail_out_v38_r7.6.) id q.c91.292fc97 (14467) for ; Sun, 10 Dec 2006 14:17:53 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Sun, 10 Dec 2006 14:17:51 EST Subject: Re: [LML] Observed Comm Mic Interference with JPI and TITs X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1165778271" X-Mailer: 9.0 Security Edition for Windows sub 5330 X-Spam-Flag: NO -------------------------------1165778271 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 12/10/2006 12:40:34 P.M. Central Standard Time, liegner@earthlink.net writes: this observed screwy change occurs when all comm units are OFF and their circuit breakers are pulled, and even when the PMA7000B intercom is also off with its CB pulled. Note that the observed effect is the same when everything is OFF or ON, when the mic button is toggled. It happens on both joysticks, but appears more pronounced with the pilot side mic compared to the copilot side mic button. Jeff, The PTT switch takes the line to ground. Your audio panel selects which radio will have the transmit pin taken to ground when the PTT is activated. Does your problem occur regardless of which radio is selected? The Pilot and copilot stick mounted PTTs should take the lines to the same good ground. Also, If you have one antenna, the antenna switcher (i.e. COMANT 601), also selected by the audio panel Comm1/Comm2 switch, activates the path to the appropriate radio when the PTT is pushed (grounded) and completely disconnects the non-transmitting radio from the diplexer for the duration of the PTT push. You might want to check that the ground for the PTTs is a good clean one and not possibly causing a "ground loop" condition with other devices. Are you running both 14 and 28 VDC buses? If so, is it possible may there be some cross talk between the different power buses? Note that some devices can work from 10-30 VDC but the grounds for devices on different + buses should also be to different ground busses. Otherwise, ????????????????????? <<<<<<<<< Toggling mic button (transmit) on the joystick causes the displayed TIT2 and (to a lesser extent) TIT1 values (on EAU/Chelton) to promptly increase and the separate JPI ammeter/voltmeter readings to go screwy. >>>>>>>>>> It just appears that the signal grounds or device grounds are affected by the PTT ground. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) A man has got to know his limitations. -------------------------------1165778271 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 12/10/2006 12:40:34 P.M. Central Standard Time,=20 liegner@earthlink.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>this=20 observed screwy change occurs when all comm units are OFF and
their=20 circuit breakers are pulled, and even when the PMA7000B
intercom is al= so=20 off with its CB pulled. Note that the observed
effect is the sam= e=20 when everything is OFF or ON, when the mic button
is toggled.

I= t=20 happens on both joysticks, but appears more pronounced with the
pilot=20= side=20 mic compared to the copilot side mic button.

Jeff,

The PTT switch takes the line to ground. Your audio panel selects= =20 which radio will have the transmit pin taken to ground when the PTT is=20 activated. Does your problem occur regardless of which radio is=20 selected? The Pilot and copilot stick mounted PTTs should take the lin= es=20 to the same good ground. Also, If you have one antenna, the antenna=20 switcher (i.e. COMANT 601), also selected by the audio panel Comm1/Comm2 swi= tch,=20 activates the path to the appropriate radio when the PTT is pushed=20 (grounded) and completely disconnects the non-transmitting radio f= rom=20 the diplexer for the duration of the PTT push.

You might want to check that the ground for the PTTs is a good clean on= e=20 and not possibly causing a "ground loop" condition with other devices. = Are=20 you running both 14 and 28 VDC buses? If so, is it possible may t= here=20 be some cross talk between the different power buses? Note that some=20 devices can work from 10-30 VDC but the grounds for devices on differen= t +=20 buses should also be to different ground busses.

Otherwise, ?????????????????????

<<<<<<<<<

Toggling mic button (transmit) on the joystick causes the displayed=20
TIT2 and (to a lesser extent) TIT1 values (on EAU/Chelton) to
prompt= ly=20 increase and the separate JPI ammeter/voltmeter readings to
go=20 screwy.
>>>>>>>>>>

It just appears that the signal grounds or device grounds are affected=20= by=20 the PTT ground.

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)

A m= an=20 has got to know his limitations.

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