---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Mon 09/07/09: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:52 AM - SL-30 issues (Ralph E. Capen) 2. 03:52 PM - radio noise on xmit & xponder interrogation (Rowland Carson) ________________________________ Message 1 _____________________________________ Time: 05:52:38 AM PST US From: "Ralph E. Capen" Subject: Avionics-List: SL-30 issues Folks, I'm just under 31 hours in to my test flying and have been trying to make sure everything in the panel is working properly. I'm trying to get the SL30 to power the S-TEC-30/GPSS autopilot (through the Century NSD1000 HSI) - and it doesn't seem to want to play. In the test mode, I can get the to/from, left/right, up/down, and NAV/GS flags to do what they're supposed to so I'm pretty confident that the wiring is OK. I can also tune in and hear the morse for the VOR station and verify the correct radial (with another NAV radio that isn't hooked to the autopilot) and the SL30 correctly displays to/from station and radial on it's face - So I'm thinking that the radio is working OK. Obviously, I need to break out the user manual for this thing - and maybe brush up on my VOR navigation techniques (but I was able to verify station and radial with another NAV radio). I think that I may also need to call Garmin/UPSAT/Apollo/IIMorrow tech support...after I read the manual. What do you think - what are the chances that my radio display output is hosed? It needs to go back for the SB fix anyway - so I may just bite the bullet..... Thanks, Ralph N822AR @ N06 - still flying off the hours...... ________________________________ Message 2 _____________________________________ Time: 03:52:11 PM PST US From: Rowland Carson Subject: Avionics-List: radio noise on xmit & xponder interrogation My friend Tim (who does not inhabit this list) has had a problem arise with his comm radio that seems to have arisen suddenly, without any changes to the installation. He has a MicroAir 760 comm radio, with a FlightTech ITC402P intercom, installed in a Europa. Symptoms: intercom works fine, other stations' transmissions heard fine. When either (P1 or P2) of the PTT buttons is pressed, a loud distorted noise immediately occurs in both (noise-cancelling) headsets. The words of the person speaking are barely discernable through this. However, anyone listening to the transmission on another comm radio hears the voice OK with no distortion (well, no more than usual on any airband R/T!). So, the bad stuff is only happening on the sidetone circuit, not on the signal going out to the transmitter. A noise also occurs when the transponder is interrogated. It's usually not quite so loud as that heard with the PTT, and sounds like white noise in character. This does seem to come and go - on a recent trip we got so fed up with TSST, TSST, TSST at irregular intervals in the headphones that we turned off the xponder on the outbound leg because we couldn't concentrate. On the return leg we tried it to see if it was still happening - it seemed considerably quieter and then after some time ceased to occur at all (we were still getting interrogated). However, the distorted sidetone problem remained unabated. These may be 2 separate things but it's suspicious they have materialised at the same time. I'm a bit puzzled as to why this should have suddenly sprung up. My feeling is that it may be some poor earthing or poor screening in the microphone leads. But it would need to be somewhere common to both headset circuits as it is affecting each equally. We are planning a longer trip this weekend (3 hours each way) and will need to do much more talking this time. If there was a simple fix to try before then I'd love to hear about it! regards Rowland -- | Rowland Carson http://home.clara.net/rowil/ | ... that's Rowland with a 'w' ... ------------------------------------------------------------------------------------- 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.