---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 01/24/17: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:06 AM - Re: iCom Antenna Switchbox effect on Com Radio (Robert L. Nuckolls, III) 2. 07:37 AM - Re: iCom Antenna Switchbox effect on Com Radio (user9253) 3. 08:48 AM - Re: Visio symbols (Josh Tinkham) 4. 10:17 AM - Re: Re: iCom Antenna Switchbox effect on Com Radio (Ken Ryan) 5. 01:16 PM - Re: Re: iCom Antenna Switchbox effect on Com Radio (Alec Myers) ________________________________ Message 1 _____________________________________ Time: 03:06:33 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: iCom Antenna Switchbox effect on Com Radio At 05:27 PM 1/23/2017, you wrote: >iCom makes a little box for allowing com antenna >to be used by their handheld radio, in the event >the primary com fails. This requires splitting >the coax from the com transceiver to the antenna into two lengths. > >My question is, will using this box have a >negative effect on either reception or >transmission of the com radio? (as compared with >identical system with just an unbroken coax from transceiver to antenna). > >Here is a link to the iCom box on Aircraft >Spruce:=C2 >http://www.aircraftspruce.com/catalog/avpages/icomswitchbox.php?clic kkey=3576 King Radio did one of these too, many moons ago. http://tinyurl.com/zympb82 Icom came along later with their version. I'm mystified as to where the designer's head was. They had little if any appreciation for the value of conserving space and volume. I purchased one of those some years ago and did a teardown. The jack is a simple, closed circuit monophonic audio jack of rather flimsy construction. http://tinyurl.com/gsatjvz http://tinyurl.com/j9qwrjj Pardon my 'french' but that little box is a piece of you-know-what. In answer to your first question, that box is 100x more likely to disable your panel mounted radio than it is to be your communications salvation for pressing your hand-held into service. Qualities of the audio jack not withstanding, the ICOM design made no effort to maintain coaxial feedline integrity. It's also unnecessarily bulky. I went to the bench and fabricated this alternative http://tinyurl.com/jyhzgyf It has a few redeeming qualities over the ICOM product but was difficult to build . . . decided not to propose it. In the mean time, conversations with folks here on the List evolved this idea: First, it would be nice if the external antenna feed line made a more graceful integration with the hand-held. http://tinyurl.com/jpccdkz http://tinyurl.com/zrxsvc3 http://tinyurl.com/h5pd4vo Some coax fittings and a rubber-band helps to dress up the interface. Breaking into the panel radio's coax offers several options. First, you need a coax joint in the feed line that is accessible to the pilot. This means a mated pair of connectors like this . . . http://tinyurl.com/h2p7ww4 or this . . . http://tinyurl.com/jug4864 on the radio side of the junction mated to this . . . http://tinyurl.com/grcap2r . . . on antenna side. Some builders have installed a 'service loop' of extra coax coiled up and held in place with velcro-ties. When the junction is opened, the extra coax is easily extended to go up the back side of the radio to the collection of adapters cited above. Alternatively, one could use a short extension cable . . . http://tinyurl.com/je4xyyg but this means another piece of 'loose gear' in the cockpit. But it could be stored in the flight bag with the radio. There are many articles on aviation websites that speak to this topic. Here is but one . . . http://tinyurl.com/hq9a7zx Bottom line is that hand-held performance is no better that the weakest link in the propagation of energy between your radio and the radio at the other end. Giving a hand-held radio access to the ship's external comm antenna with a minimum parts count and maximized feed line integrity is a GOOD thing. This posting could be easily ported to a "Shop Notes" article on the website. I'll let you guys have first crack at it. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:37:53 AM PST US Subject: AeroElectric-List: Re: iCom Antenna Switchbox effect on Com Radio From: "user9253" Com radios do not fail very often. When yours does fail, the cause is likely to be icom's little antenna switch box or the coax or antenna. If so, the handheld radio will not work either. How about a separate antenna, either external or internal? Maybe Jim Weir's copper tape antenna on a window? -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=465398#465398 ________________________________ Message 3 _____________________________________ Time: 08:48:15 AM PST US From: Josh Tinkham Subject: AeroElectric-List: Re: Visio symbols Thanks for the .DWG tip, that totally got me started. Maybe if I get bored I'll re-export the symbols in a file compatible with newer Visio installations. Stay tuned for my RV-10 Z-14 questions -Josh ________________________________ Message 4 _____________________________________ Time: 10:17:49 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: Re: iCom Antenna Switchbox effect on Com Radio Thanks for the inputs. I wondered about the quality of the thing. I think I will not install it. Will probably just carry handheld and hope for the best. Last time I checked, airplane flies good without radio. On Tue, Jan 24, 2017 at 6:29 AM, user9253 wrote: > > Com radios do not fail very often. When yours does fail, the cause is > likely to be icom's little antenna switch box or the coax or antenna. If > so, the handheld radio will not work either. How about a separate antenna, > either external or internal? Maybe Jim Weir's copper tape antenna on a > window? > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=465398#465398 > > ________________________________ Message 5 _____________________________________ Time: 01:16:32 PM PST US Subject: Re: AeroElectric-List: Re: iCom Antenna Switchbox effect on Com Radio From: Alec Myers I installed something like this; it uses a switched 3.5mm jack socket to interrupt the centre conductor of the coax. It's a complete disaster as far as ERP goes. However now that it's mounted on the panel, I have a convenient break in point to the no.2 comm antenna because I can reach under and disconnect the BNC connector on the back of the thing and access the cable to the antenna. Now I carry a spare coax cable with a barrel connector to connect my handeld at that point. The combination of very low transmit power, the frankly laughably inefficient rubber whip antenna, and the shielding effects of the airframe on the handheld all mean that the range from inside aircraft with the hand-held as-is is too all intents useless. When connected to the aircraft power bus, and using the external anntenna via the coax I described above, two of the attenuating effects are mitigated and my Icom A-24 gives me about 7-8 miles range to an ATC outlet. Not great, but might one day be useful. But only with that method of connection. On 24Jan2017, at 7:13 PM, Ken Ryan wrote: Thanks for the inputs. I wondered about the quality of the thing. I think I will not install it. Will probably just carry handheld and hope for the best. Last time I checked, airplane flies good without radio. On Tue, Jan 24, 2017 at 6:29 AM, user9253 wrote: Com radios do not fail very often. When yours does fail, the cause is likely to be icom's little antenna switch box or the coax or antenna. If so, the handheld radio will not work either. How about a separate antenna, either external or internal? Maybe Jim Weir's copper tape antenna on a window? -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=465398#465398 =================================== - Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List =================================== FORUMS - eferrer" target="_blank">http://forums.matronics.com =================================== WIKI - errer" target="_blank">http://wiki.matronics.com =================================== b Site - -Matt Dralle, List Admin. rel="noreferrer" target="_blank">http://www.matronics.com/contribution =================================== ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-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/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-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.