---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Wed 02/14/07: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:20 AM - Yahoo! Auto Response (xrayperformance@yahoo.com) 2. 12:45 AM - Re: Com audio issues (John Rippengal) 3. 06:53 AM - Re: Com audio issues (Hopperdhh@aol.com) 4. 08:11 PM - Radio audio troubles () ________________________________ Message 1 _____________________________________ Time: 12:20:35 AM PST US From: xrayperformance@yahoo.com Subject: Avionics-List: Yahoo! Auto Response Thank you for for contacting us. We'll try to get back to you within the next business day. For a quicker response, please leave your item number so that we can futher assist you as well. JDM TEAM appriciate your business.Business Hours: M-F 10AM-7PM PST Sat&Sun Close ********LOOK FOR LAMBO DOOR 90DEGREE KIT*********** http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=013&sspagename=STRK%3AMESE%3AIT&viewitem=&item=230092008705&rd=1,1 ________________________________ Message 2 _____________________________________ Time: 12:45:16 AM PST US From: "John Rippengal" Subject: Re: Avionics-List: Com audio issues It could be an impedance problem. But before doing anything else it would be as well to check that there is nothing peculiar about the com2 input. Change the Becker and Icom inputs round to make sure the problem either stays with com2 (in which case the problems is with the audio panel) or changes over to com1 (in which case the problem is with the Becker) It is rather poor practice to just mechanically parallel the outputs. Normally the audio panel would provide a simple op amp circuit which would enable the outputs to be combined without affecting each other at all. Are you sure it does just parallel them all up? If it does then I would expect any output to be attenuated noticeably when paralleling multiple others. John Subject: Avionics-List: Com audio issues > > Hi Gurus, > > It's been awhile, but I hope all is well with you all. > > I'm having audio issues with my new Becker 4201 #2 com and was wondering > if > you could help. > > The issue is the output audio from the radio whenever there is another > radio > switched into the same output. As soon as any other input is selected on > the audio panel at the same time, the com#2 volume goes very very low and > is > overpowered. Sidetone during transmit seems un-affected as does the audio > of > the other sources selected - only the Com2 audio drops down. By > itself...the radio sounds fine, and operates properly. > > The #1 com (iCom A200) works fine and is nice and loud with any number of > inputs selected on the audio panel (KA-134). Adding additional inputs has > little to no affect on com1 volume. It works great - as it should. > > According to the KA-134 schematics, the only thing it's doing with the > phone > outputs from the radios is mechanically switching them (no electronics) > together to a single output line to the intercom. Because of this, I was > wondering if the impedance differences of the radios are a problem. > However, I have no real understand of the magic involved. > > They are as follows according to the respective docs: > Com1 iCom - 500 ohms > Com2 Becker - 600 ohms > Eng mon - 560 ohms > Nav KN-53 - 500 ohms > > I still puzzled why Com1 has no issues with any number of other inputs, > and > Com2 does. > > Any ideas? I have schematics for the KA-134 if you want to see it...but > for > this, it's just switches. > > Thanks for any help! > > James Redmon > Berkut13 N97TX > ________________________________ Message 3 _____________________________________ Time: 06:53:32 AM PST US From: Hopperdhh@aol.com Subject: Re: Avionics-List: Com audio issues In a message dated 2/14/2007 3:51:25 AM Eastern Standard Time, j.rippengal@cytanet.com.cy writes: It is rather poor practice to just mechanically parallel the outputs. Normally the audio panel would provide a simple op amp circuit which would enable the outputs to be combined without affecting each other at all. Are you sure it does just parallel them all up? If it does then I would expect any output to be attenuated noticeably when paralleling multiple others. John James, I agree with John. Actually the output impedance of each unit is probably not 500 or 600 ohms. It could be as small as 1 ohm or as large as 600 ohms, but designed to drive a 500 or 600 ohm load. If you put a resistor of about 200 ohms in series with each unit, then you give each one a chance to compete with the others. Dan Hopper RV-7A Retired EE ________________________________ Message 4 _____________________________________ Time: 08:11:15 PM PST US From: Subject: Avionics-List: Radio audio troubles Hi Gurus, It's been awhile, but I hope all is well with you all. I'm having audio issues with my new Becker 4201 #2 com and was wondering if you could help. The issue is the output audio from the radio whenever there is another radio switched into the same output. As soon as any other input is selected on the audio panel at the same time, the com#2 volume goes very very low and is overpowered. Sidetone during transmit seems un-affected as does the audio of the other sources selected - only the Com2 audio drops down. By itself...the radio sounds fine, and operates properly. The #1 com (iCom A200) works fine and is nice and loud with any number of inputs selected on the audio panel (KA-134). Adding additional inputs has little to no affect on com1 volume. It works great - as it should. According to the KA-134 schematics, the only thing it's doing with the phone outputs from the radios is mechanically switching them (no electronics) together to a single output line to the intercom. Because of this, I was wondering if the impedance differences of the radios are a problem. However, I have no real understanding of the magic involved here. They are as follows according to the respective docs: Com1 iCom - 500 ohms Com2 Becker - 600 ohms Eng mon - 560 ohms Nav KN-53 - 500 ohms RST Marker Receiver - unknown I am still puzzled why Com1 has no issues with any number of other inputs, and Com2 does....impedance differences and all. Any ideas? I have schematics for the KA-134 if you want to see it...but for this, it's just mechanical switches. Thanks for any help! James Redmon Berkut13 N97TX ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message avionics-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Avionics-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/avionics-list Browse Digests http://www.matronics.com/digest/avionics-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.