---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 02/25/15: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:38 AM - Re: Handheld transceiver alternate antenna (David Josephson) 2. 03:47 AM - Re: Re: Handheld transceiver alternate antenna (John MacCallum) 3. 04:51 AM - Re: Having several issues with my installation (curts63) 4. 06:01 AM - Re: Re: Handheld transceiver alternate antenna (BobsV35B@aol.com) 5. 07:10 AM - Re: Having several issues with my installation (curts63) 6. 09:00 AM - Re: Re: Handheld transceiver alternate antenna (Ken Ryan) 7. 02:02 PM - Re: Re: Handheld transceiver alternate antenna (John MacCallum) 8. 02:10 PM - antenna switch for handheld (Andy Elliott) 9. 02:14 PM - Re: Re: Handheld transceiver alternate antenna (John MacCallum) 10. 02:22 PM - Re: Re: Handheld transceiver alternate antenna (Ken Ryan) 11. 02:27 PM - Shield grounds (Aeroelectric) 12. 02:34 PM - Re: Re: Handheld transceiver alternate antenna (Bill Maxwell) 13. 03:05 PM - Re: Re: Handheld transceiver alternate antenna (rv7a.builder) 14. 06:28 PM - Re: Re: Handheld transceiver alternate antenna (Dj Merrill) 15. 06:32 PM - Re: Re: Handheld transceiver alternate antenna (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 12:38:41 AM PST US Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna From: David Josephson On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net wrote: > To clarify a little, I was thinking of installing a BNC tee in the line between > the panel mounted radio and the antenna. Then I would bring a short "branch" > from that tee to a panel-mounted male BNC, and possibly close that off with the > proper terminating cap until it is used. I would have a short section of antenna > cable with connectors already attached to and stored with the handheld. Would > this kind of arrangement have shortcomings in the way of signal strength > or other losses? Yes, many. It won't work. RF is not like water pipe. Besides damaging whichever radio was not transmitting, the impedance mismatch would badly compromise receive and transmit range. ________________________________ Message 2 _____________________________________ Time: 03:47:59 AM PST US From: John MacCallum Subject: RE: AeroElectric-List: Re: Handheld transceiver alternate antenna Yes RF is not like water. It's far more fickle and you can't use a terminating cap because of the power involved during transmit. You would fry a terminating resistor that was plugged into the free port plus the impedance would be halved. Hence an SWR of 2:1 before it even gets to the antenna. A tee in the feedline is not a good idea. It will work but there are a lot of things that can go wrong with that setup. Up to and including accidently transmitting into your HH with the ships radio or visa versa. It is best to use a Coaxial switch or have a patch panel. To make a Patch panel you will need one BNC socket (female) and one Connector (male) mounted on a small bracket and a Jumper Lead with one Connector and one socket. The Jumper plugs into the Ships Radio via a socket and a socket on the other end goes to the Antenna via the from the connector. You disconnect the Ships Radio end of the jumper and plug into the hand held. The reason for making the jumper male and female is so you don't accidently plug into the Ships radio with the Hand Held. Don't laugh it is easy done! I still vote for a coaxial switch it's a lot easier. They can be bought for not much money from a Ham Radio supplier. Cheers John MacCallum VH-DUU RV 10 # 41016 -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David Josephson Sent: Wednesday, 25 February 2015 7:38 PM Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna --> On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net wrote: > To clarify a little, I was thinking of installing a BNC tee in the > line between the panel mounted radio and the antenna. Then I would bring a short "branch" > from that tee to a panel-mounted male BNC, and possibly close that off > with the proper terminating cap until it is used. I would have a short > section of antenna cable with connectors already attached to and > stored with the handheld. Would this kind of arrangement have > shortcomings in the way of signal strength or other losses? Yes, many. It won't work. RF is not like water pipe. Besides damaging whichever radio was not transmitting, the impedance mismatch would badly compromise receive and transmit range. ________________________________ Message 3 _____________________________________ Time: 04:51:44 AM PST US Subject: AeroElectric-List: Re: Having several issues with my installation From: "curts63" I'm located in eastern PA. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438703#438703 ________________________________ Message 4 _____________________________________ Time: 06:01:10 AM PST US From: BobsV35B@aol.com Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna Good Morning All, Just to jump in on a message already well answered, I would like to add my thoughts. We have a Piper Pacer equipped with just one radio. A Garmin 430W. The aircraft is flown IFR regularly. In order to add a bit of reliable back up, we do carry a handheld and have installed a separate external antenna just for that radio. It is a bit of extra drag and a bit more weight, but when a back up is actually needed, it is nice to know that the unit has an antenna all of it's own. Just my idea of a full backup totally separated from the primary radio system. Decisions, decisions. All the time decisions! Happy Skies, Old Bob AKA Bob Siegfried Ancient Aviator PA-20 Brookeridge Air Park LL22 Downers Grove, IL ________________________________ Message 5 _____________________________________ Time: 07:10:34 AM PST US Subject: AeroElectric-List: Re: Having several issues with my installation From: "curts63" I'm ashamed and embarassed by my doodling, but here is a sketch of what I have. Remember, I don't know the correct symbols, terms, or designs that engineers should use. This can be the drawing you hang around the office for others to mock. The one drawing shows the basic wiring idea. The battery is grounded to the firewall, starter, and both ground blocks. The power goes from the battery to the starter solenoid, also from the battery to the shunt- then splits to the power panel with built in switches and some type of self resetting fuses to the relay which provides power to the other bus. You'll have to excuse my not remembering the exact way the relays are wired, but it does work for battery backup. The alternator has two wires to the regulator, the regulator is grounded to the firewall and feeds back to the battery (there is a sense wire that turns on/off the regulator). The "main bus" has actual circuit breakers mounted to a copper strip. These power the avionics , such as radios, transponder, GDL, GPS, ADHRS, and one EFIS. I believe all shielded wires used are grounded on the backshell and floating on the other ends. Regular power and ground for individual units are not shielded. The interconnect for the Garmin items use a canbus or RS232, with twisted and shielded pairs. http://centroidproducts.com/3wire.htm this is where the fuel probes come from. The power, ground and sense connect to the GEA-24 and use 5v reference. If you have any other questions, please ask and I'll attempt to answer the best I can. If someone feels they can help, feel free to ask for my cell number and we can talk to better understand. Thanks, Curt Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438710#438710 Attachments: http://forums.matronics.com//files/schematic_2_988.pdf http://forums.matronics.com//files/schematic_1_130.pdf ________________________________ Message 6 _____________________________________ Time: 09:00:40 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna Attached is a pdf data sheet for a coaxial switch. Question: would this switch be a good choice? On Wed, Feb 25, 2015 at 2:46 AM, John MacCallum wrote: > john.maccallum@bigpond.com> > > Yes RF is not like water. It's far more fickle and you can't use a > terminating cap because of the power involved during transmit. You would > fry > a terminating resistor that was plugged into the free port plus the > impedance would be halved. Hence an SWR of 2:1 before it even gets to the > antenna. > A tee in the feedline is not a good idea. It will work but there are a lot > of things that can go wrong with that setup. Up to and including > accidently transmitting into your HH with the ships radio or visa versa. > > It is best to use a Coaxial switch or have a patch panel. > > To make a Patch panel you will need one BNC socket (female) and one > Connector (male) mounted on a small bracket and a Jumper Lead with one > Connector and one socket. The Jumper plugs into the Ships Radio via a > socket > and a socket on the other end goes to the Antenna via the from the > connector. You disconnect the Ships Radio end of the jumper and plug into > the hand held. The reason for making the jumper male and female is so you > don't accidently plug into the Ships radio with the > Hand Held. Don't laugh it is easy done! I still vote for a coaxial switch > it's a lot easier. They can be bought for not much money from a Ham Radio > supplier. > > > Cheers > > John MacCallum > VH-DUU > RV 10 # 41016 > > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David > Josephson > Sent: Wednesday, 25 February 2015 7:38 PM > To: AeroElectric-List Digest Server > Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna > > --> > > > On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net wrote: > > > To clarify a little, I was thinking of installing a BNC tee in the > > line between the panel mounted radio and the antenna. Then I would bring > a > short "branch" > > from that tee to a panel-mounted male BNC, and possibly close that off > > with the proper terminating cap until it is used. I would have a short > > section of antenna cable with connectors already attached to and > > stored with the handheld. Would this kind of arrangement have > > shortcomings in the way of signal strength or other losses? > > Yes, many. It won't work. RF is not like water pipe. Besides damaging > whichever radio was not transmitting, the impedance mismatch would badly > compromise receive and transmit range. > > ________________________________ Message 7 _____________________________________ Time: 02:02:48 PM PST US From: John MacCallum Subject: RE: AeroElectric-List: Re: Handheld transceiver alternate antenna Probably a little bit of overkill for what you want it for. That particular one has a relay so that you can remote switch it. You can get good quality manual ones for a lot less than what that will cost although of course not quite as neat and tidy as a remote mounted switch such as that. A quick search around I can find some N type connector switches for around $50. You would need to terminate the Antenna Feedline with and N connector for the one in the link below but that=99s actually a better specification than BNC. If you look around a bit you could probably find a BNC terminated type. http://www.hamradio.com/detail.cfm?pid=H0-003421 Cheers John MacCallum VH-DUU RV 10 # 41016 From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ken Ryan Sent: Thursday, 26 February 2015 3:58 AM Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna Attached is a pdf data sheet for a coaxial switch. Question: would this switch be a good choice? On Wed, Feb 25, 2015 at 2:46 AM, John MacCallum wrote: Yes RF is not like water. It's far more fickle and you can't use a terminating cap because of the power involved during transmit. You would fry a terminating resistor that was plugged into the free port plus the impedance would be halved. Hence an SWR of 2:1 before it even gets to the antenna. A tee in the feedline is not a good idea. It will work but there are a lot of things that can go wrong with that setup. Up to and including accidently transmitting into your HH with the ships radio or visa versa. It is best to use a Coaxial switch or have a patch panel. To make a Patch panel you will need one BNC socket (female) and one Connector (male) mounted on a small bracket and a Jumper Lead with one Connector and one socket. The Jumper plugs into the Ships Radio via a socket and a socket on the other end goes to the Antenna via the from the connector. You disconnect the Ships Radio end of the jumper and plug into the hand held. The reason for making the jumper male and female is so you don't accidently plug into the Ships radio with the Hand Held. Don't laugh it is easy done! I still vote for a coaxial switch it's a lot easier. They can be bought for not much money from a Ham Radio supplier. Cheers John MacCallum VH-DUU RV 10 # 41016 -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David Josephson Sent: Wednesday, 25 February 2015 7:38 PM Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna --> On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net wrote: > To clarify a little, I was thinking of installing a BNC tee in the > line between the panel mounted radio and the antenna. Then I would bring a short "branch" > from that tee to a panel-mounted male BNC, and possibly close that off > with the proper terminating cap until it is used. I would have a short > section of antenna cable with connectors already attached to and > stored with the handheld. Would this kind of arrangement have > shortcomings in the way of signal strength or other losses? Yes, many. It won't work. RF is not like water pipe. Besides damaging whichever radio was not transmitting, the impedance mismatch would badly compromise receive and transmit range. - Electric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List FORUMS - _blank">http://forums.matronics.com b Site - -Matt Dralle, List Admin. target="_blank">http://www.matronics.com/contribution ________________________________ Message 8 _____________________________________ Time: 02:10:52 PM PST US From: "Andy Elliott" Subject: AeroElectric-List: antenna switch for handheld It turns out that ICOM produces a convenient little, optionally panel-mounted device for exactly what you need, under the name Antenna Switchbox, P/N IC-ANT-SB, which can be had for $64 from Aircraft Spruce including the BNC-terminate interconnect cable for your handheld. I made one of these myself maybe 10-12 years ago for an old airplane, but nowadays would just spend the money! Basically, it is a soldered-closed brass box with two BNC connectors on the back and a 3.5mm audio plug jack with a NC switch on the front. Lots of variety on Mouser. (My homemade version used a 1/4" plug.) Closed brass box protects the signal from interference. The thing is wired so that input BNC from the panel-mount is connected to the output BNC to the antenna through the NC switch when the jack is empty. When you connect the handheld, the plug opens the switch in the jack and disconnects the panel mount, while connecting the handheld to the antenna. Pretty idiot proof. FWIW, Andy Elliott ________________________________ Message 9 _____________________________________ Time: 02:14:51 PM PST US From: John MacCallum Subject: RE: AeroElectric-List: Re: Handheld transceiver alternate antenna Yes Bob that was something else I thought about to suggest. If the extra drag is not an issue a dedicated antenna is a good solution. Cheers John MacCallum VH-DUU RV 10 # 41016 From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of BobsV35B@aol.com Sent: Thursday, 26 February 2015 1:00 AM Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna Good Morning All, Just to jump in on a message already well answered, I would like to add my thoughts. We have a Piper Pacer equipped with just one radio. A Garmin 430W. The aircraft is flown IFR regularly. In order to add a bit of reliable back up, we do carry a handheld and have installed a separate external antenna just for that radio. It is a bit of extra drag and a bit more weight, but when a back up is actually needed, it is nice to know that the unit has an antenna all of it's own. Just my idea of a full backup totally separated from the primary radio system. Decisions, decisions. All the time decisions! Happy Skies, Old Bob AKA Bob Siegfried Ancient Aviator PA-20 Brookeridge Air Park LL22 Downers Grove, IL ________________________________ Message 10 ____________________________________ Time: 02:22:21 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna Not considering price, are the specs what they should be? And to those suggesting the switch is the best solution, wouldn't there exist the danger of the switch being in the wrong position, and then trying to transmit with the equivalent of "no antenna" attached? I've heard that's not a smart thing to do. On Wed, Feb 25, 2015 at 12:59 PM, John MacCallum wrote: > Probably a little bit of overkill for what you want it for. That > particular one has a relay so that you can remote switch it. You can get > good > > quality manual ones for a lot less than what that will cost although of > course not quite as neat and tidy as a remote mounted switch such as that .. > > > A quick search around I can find some N type connector switches for aroun d > $50. You would need to terminate the Antenna Feedline with and N connecto r > > for the one in the link below but that=99s actually a better specif ication > than BNC. If you look around a bit you could probably find a BNC terminat ed > type. > > > http://www.hamradio.com/detail.cfm?pid=H0-003421 > > > Cheers > > > John MacCallum > > VH-DUU > > RV 10 # 41016 > > > *From:* owner-aeroelectric-list-server@matronics.com [mailto: > owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Ken Ryan > *Sent:* Thursday, 26 February 2015 3:58 AM > *To:* aeroelectric-list@matronics.com > *Subject:* Re: AeroElectric-List: Re: Handheld transceiver alternate > antenna > > > Attached is a pdf data sheet for a coaxial switch. Question: would this > switch be a good choice? > > > On Wed, Feb 25, 2015 at 2:46 AM, John MacCallum < > john.maccallum@bigpond.com> wrote: > > john.maccallum@bigpond.com> > > Yes RF is not like water. It's far more fickle and you can't use a > terminating cap because of the power involved during transmit. You would > fry > a terminating resistor that was plugged into the free port plus the > impedance would be halved. Hence an SWR of 2:1 before it even gets to the > antenna. > A tee in the feedline is not a good idea. It will work but there are a lo t > of things that can go wrong with that setup. Up to and including > accidently transmitting into your HH with the ships radio or visa versa. > > It is best to use a Coaxial switch or have a patch panel. > > To make a Patch panel you will need one BNC socket (female) and one > Connector (male) mounted on a small bracket and a Jumper Lead with one > Connector and one socket. The Jumper plugs into the Ships Radio via a > socket > and a socket on the other end goes to the Antenna via the from the > connector. You disconnect the Ships Radio end of the jumper and plug into > the hand held. The reason for making the jumper male and female is so you > don't accidently plug into the Ships radio with the > Hand Held. Don't laugh it is easy done! I still vote for a coaxial switc h > it's a lot easier. They can be bought for not much money from a Ham Radio > supplier. > > > Cheers > > John MacCallum > VH-DUU > RV 10 # 41016 > > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David > Josephson > Sent: Wednesday, 25 February 2015 7:38 PM > To: AeroElectric-List Digest Server > Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna > > --> > > > On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net wrote: > > > To clarify a little, I was thinking of installing a BNC tee in the > > line between the panel mounted radio and the antenna. Then I would brin g > a > short "branch" > > from that tee to a panel-mounted male BNC, and possibly close that off > > with the proper terminating cap until it is used. I would have a short > > section of antenna cable with connectors already attached to and > > stored with the handheld. Would this kind of arrangement have > > shortcomings in the way of signal strength or other losses? > > Yes, many. It won't work. RF is not like water pipe. Besides damaging > whichever radio was not transmitting, the impedance mismatch would badly > compromise receive and transmit range. > > > ========== > - > Electric-List" target="_blank"> > http://www.matronics.com/Navigator?AeroElectric-List > ========== > FORUMS - > _blank">http://forums.matronics.com > ========== > b Site - > -Matt Dralle, List Admin. > target="_blank">http://www.matronics.com/contribution > ========== > > > * > =========== www.matronics.com/Navigator?AeroElectric-List> =========== =========== om/contribution> =========== > > * > > ________________________________ Message 11 ____________________________________ Time: 02:27:35 PM PST US From: Aeroelectric Subject: AeroElectric-List: Shield grounds I thought I understood how shield grounds worked and how to implement them but now looking at a Garmin G3X. The garmin manual specifically has some of the shields terminated on both ends and grounded. some of the shields are only terminated and grounder on one end and the other is floating. So what is the proper termination of shields and what is the science behind the proper methods. John Snapp ( excuse the typos. This email was sent from a mobile device!) ________________________________ Message 12 ____________________________________ Time: 02:34:46 PM PST US From: Bill Maxwell Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna It could be made to work Ken but it is more complicated than necessary. It also needs a 12 volt supply and utilises SMA connectors. I suggest you look for a much simpler mechanical switch type.They are commonly available from ham radio suppliers and usually are fitted with SO-239 connectors. Connection is selected by simply turning a knob or flicking a switch. Better reliability. Bill On 26/02/2015 3:58 AM, Ken Ryan wrote: > Attached is a pdf data sheet for a coaxial switch. Question: would > this switch be a good choice? > > On Wed, Feb 25, 2015 at 2:46 AM, John MacCallum > > wrote: > > > > > Yes RF is not like water. It's far more fickle and you can't use a > terminating cap because of the power involved during transmit. You > would fry > a terminating resistor that was plugged into the free port plus the > impedance would be halved. Hence an SWR of 2:1 before it even gets > to the > antenna. > A tee in the feedline is not a good idea. It will work but there > are a lot > of things that can go wrong with that setup. Up to and including > accidently transmitting into your HH with the ships radio or visa > versa. > > It is best to use a Coaxial switch or have a patch panel. > > To make a Patch panel you will need one BNC socket (female) and one > Connector (male) mounted on a small bracket and a Jumper Lead with one > Connector and one socket. The Jumper plugs into the Ships Radio > via a socket > and a socket on the other end goes to the Antenna via the from the > connector. You disconnect the Ships Radio end of the jumper and > plug into > the hand held. The reason for making the jumper male and female is > so you > don't accidently plug into the Ships radio with the > Hand Held. Don't laugh it is easy done! I still vote for a > coaxial switch > it's a lot easier. They can be bought for not much money from a > Ham Radio > supplier. > > > Cheers > > John MacCallum > VH-DUU > RV 10 # 41016 > > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > > [mailto:owner-aeroelectric-list-server@matronics.com > ] On Behalf > Of David > Josephson > Sent: Wednesday, 25 February 2015 7:38 PM > To: AeroElectric-List Digest Server > Subject: AeroElectric-List: Re: Handheld transceiver alternate antenna > > --> > > > > On Feb 25, 2015, at 12:00 AM, jrevens@comcast.net > wrote: > > > To clarify a little, I was thinking of installing a BNC tee in the > > line between the panel mounted radio and the antenna. Then I > would bring a > short "branch" > > from that tee to a panel-mounted male BNC, and possibly close > that off > > with the proper terminating cap until it is used. I would have a > short > > section of antenna cable with connectors already attached to and > > stored with the handheld. Would this kind of arrangement have > > shortcomings in the way of signal strength or other losses? > > Yes, many. It won't work. RF is not like water pipe. Besides damaging > whichever radio was not transmitting, the impedance mismatch would > badly > compromise receive and transmit range. > > > ========== > - > Electric-List" > target="_blank">http://www.matronics.com/Navigator?AeroElectric-List > ========== > FORUMS - > _blank">http://forums.matronics.com > ========== > b Site - > -Matt Dralle, List Admin. > target="_blank">http://www.matronics.com/contribution > ========== > > ________________________________ Message 13 ____________________________________ Time: 03:05:04 PM PST US From: "rv7a.builder" Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna ________________________________ Message 14 ____________________________________ Time: 06:28:31 PM PST US Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna From: Dj Merrill I have a Narco VP-16 antenna switch that I will sell for $25 including shipping in the continental US. It uses BNC connectors, and switches one antenna between two radios. It is essentially an electrical relay that switches with 12v. Wiring connector included. Pic on my website http://deej.net/forsale/ -Dj -- Dj Merrill - N1JOV - EAA Chapter 87 Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/ Glastar Flyer N866RH - http://deej.net/glastar/ ________________________________ Message 15 ____________________________________ Time: 06:32:37 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Handheld transceiver alternate antenna At 16:34 2015-02-25, you wrote: >It could be made to work Ken but it is more complicated than >necessary. It also needs a 12 volt supply and utilises SMA >connectors. I suggest you look for a much simpler mechanical switch >type. They are commonly available from ham radio suppliers and >usually are fitted with SO-239 connectors. Connection is selected by >simply turning a knob or flicking a switch. Better reliability. Most COTS antenna switches are designed to select from two or more antennas to a single transceiver/receiver . . . there are no concerns for leaving "the alternate transceiver" unterminated. It turns out that ICOM produces a convenient little, optionally panel-mounted device for exactly what you need, under the name Antenna Switchbox, P/N IC-ANT-SB, which can be had for $64 from Aircraft Spruce including the BNC-terminate interconnect cable for your handheld. Yes, I purchased one about a dozen years ago and dissected it. http://tinyurl.com/nn2sysd http://tinyurl.com/pp6tzgv . . . yes, it performs as advertised but not very sanitary with respect to managing a transmission line. Another concern for me was a kind flimsy, normally-closed contact on the jack that was supposed provide center-conductor integrity through the adapter. Finally, the ICOM product was pretty over-sized to the task. I fiddled with a DIY version . . . http://tinyurl.com/kluld58 . . . that didn't put as bit a 'lump' in the transmission line's RF profile. It was a lot less demanding of panel real estate. But it still offered lackluster robustness due to quality of the n.c. audio jack being pressed into service as a coax connector. I toyed with the idea of offering a crew accessible antenna switch that would terminate the OFF transceiver line in a little dummy load. I think I offered to bring one into being as an AEC product if I could get a commitment for purchase of some small quantity of units . . . I think it was ten. That didn't rise off the ground either. SSSsoooooo . . . a completely independent antenna or a DIY 'patch cable' of some arrangement are the elegant choices. 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