If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Transponder antenna installations
On Feb 6, 11:12*am, jcarlyle wrote:
I understand your point - I saw those suggestions on my L2 instructions, laughed, and pitched it. Why should you pay for transponder output just to heat up the antenna cable with outdated RG-58, when low loss LM240 is only $0.70 more per foot? And if RG-58 is bad, RG-174 is 4 times worse... -John On Feb 6, 1:27 pm, JJ Sinclair wrote: The instructions from Advanced Aircraft Electronics call for RG-58A/U unless wire bundle size is critical where the smaller RG-174/U may be used if length is held to 20 feet or less. JJ- Hide quoted text - - Show quoted text - You're right John.................I'll disregard the manufactures instructions and go with something I heard on ras............. Yeah, right! JJ |
#12
|
|||
|
|||
Transponder antenna installations
Good point - everything on RAS is always suspect.
Would you believe an attenuation calculator from Times Microwave? See http://www.timesmicrowave.com/cgi-bin/calculate.pl Another option is to look up attenuation values on Newark and Allied, since a manufacturer has a vested interest in lying. Oh, wait - Advanced Airborne Electronics is a manufacturer... -John On Feb 6, 2:18 pm, JJ Sinclair wrote: You're right John.................I'll disregard the manufactures instructions and go with something I heard on ras............. Yeah, right! JJ |
#13
|
|||
|
|||
Transponder antenna installations
On Feb 6, 1:14*pm, "John Scott" wrote:
I installed an L-2 antenna with my transponder. *While my wings and tailboom are carbon fiber, the nose of my glider is fiberglass. *I installed the L-2 vertically on the bulkhead that closes off the nose ahead of my feet. *I've not noticed any effect on my other instruments in the panel or on my GPS (CA302). *I have noticed that my feet still get cold at altitude, so I don't think the power output is a problem. *The vertical orientation means my glider is at the center of a very fat horizontal donut. John Scott We did an LS-3 this way with good results. Cookie |
#14
|
|||
|
|||
Transponder antenna installations
On 2/6/2011 11:18 AM, JJ Sinclair wrote:
On Feb 6, 11:12 am, wrote: I understand your point - I saw those suggestions on my L2 instructions, laughed, and pitched it. Why should you pay for transponder output just to heat up the antenna cable with outdated RG-58, when low loss LM240 is only $0.70 more per foot? And if RG-58 is bad, RG-174 is 4 times worse... The instructions from Advanced Aircraft Electronics call for RG-58A/U unless wire bundle size is critical where the smaller RG-174/U may be used if length is held to 20 feet or less. JJ- Hide quoted text - - Show quoted text - You're right John.................I'll disregard the manufactures instructions and go with something I heard on ras............. Yeah, right! JJ, call AAE and ask about the LM240 cable. It might be their recommendation was aimed at airplanes carrying 200+ watt transponders and using shorter cable runs, compared to gliders that might using units with 150 watts or less and long cable runs. Also, looking at the transponder manufacturer's recommendation is probably a better indication of what's needed than the antenna manufacturer. My Becker instructions made quite a fuss about which cable to use. Generally, I like to go the "good stuff" for transponders, as attenuation per foot is much higher at transponder frequencies than our communication radios frequencies (factor of 8). -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) |
#15
|
|||
|
|||
Transponder antenna installations
Hi,
The Trig TT21 and TT22 manual is also quite fussy about transponder antenna cable. But it important to note that many of the "long run" antenna cables they recommend are extremely expensive. I recommend mounting the transponder unit (it is separate from the control head) as close to the antenna as possible. When that is done I have received customer feedback that RG-58 cable works fine - with all required tests passed with flying colors. Paul Remde "Eric Greenwell" wrote in message ... On 2/6/2011 11:18 AM, JJ Sinclair wrote: On Feb 6, 11:12 am, wrote: I understand your point - I saw those suggestions on my L2 instructions, laughed, and pitched it. Why should you pay for transponder output just to heat up the antenna cable with outdated RG-58, when low loss LM240 is only $0.70 more per foot? And if RG-58 is bad, RG-174 is 4 times worse... The instructions from Advanced Aircraft Electronics call for RG-58A/U unless wire bundle size is critical where the smaller RG-174/U may be used if length is held to 20 feet or less. JJ- Hide quoted text - - Show quoted text - You're right John.................I'll disregard the manufactures instructions and go with something I heard on ras............. Yeah, right! JJ, call AAE and ask about the LM240 cable. It might be their recommendation was aimed at airplanes carrying 200+ watt transponders and using shorter cable runs, compared to gliders that might using units with 150 watts or less and long cable runs. Also, looking at the transponder manufacturer's recommendation is probably a better indication of what's needed than the antenna manufacturer. My Becker instructions made quite a fuss about which cable to use. Generally, I like to go the "good stuff" for transponders, as attenuation per foot is much higher at transponder frequencies than our communication radios frequencies (factor of 8). -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) |
#16
|
|||
|
|||
Transponder antenna installations
On Feb 6, 9:57*am, jcarlyle wrote:
JJ, please don't use RG-58 for a transponder cable - it has very high attenuation per foot. Times Microwave LM240 is a much better choice, with only 1/3 of the attenuation of RG-58 at 1 GHz. I usually use Times Microwave LM300, with only 1/4 the attenuation of RG-58, but it has double the diameter. Both of these cables have a greater than 20 year life outdoors. -john On Feb 6, 9:07 am, JJ Sinclair wrote: I second the L-2, di-pole antenna suggestion, all inside with nothing sticking out to get ripped off. Carve a1"X 1"X4" balsawood block so that it matches the inside curve of your non-carbon fuselage, then glue the antenna vertical to the flat side and the curved side to the inside aft fuselage. *Keep it about 6" away from metal objects like your elevator push-rod, etc. Secure the RG-58 lead so that it can't get tangled with controls and you're good to go. Hope this helps, JJ- Hide quoted text - - Show quoted text - The Becker 4401-175 manual does say that RG-223/U is preferred over RGU-58, but it doesn't mention LM-240? As a mechanic I am bound to follow the appropriate tech data. Does LM-240 use the same BNC fittings I have in stock? Can I use my crimper? What would my log book entry say? Installed Becker 4401-175 transponder in accordance with opinions found on ras? :) JJ |
#17
|
|||
|
|||
Transponder antenna installations
On Mon, 7 Feb 2011 06:18:57 -0800 (PST), JJ Sinclair
wrote: On Feb 6, 9:57*am, jcarlyle wrote: JJ, please don't use RG-58 for a transponder cable - it has very high attenuation per foot. Times Microwave LM240 is a much better choice, with only 1/3 of the attenuation of RG-58 at 1 GHz. I usually use Times Microwave LM300, with only 1/4 the attenuation of RG-58, but it has double the diameter. Both of these cables have a greater than 20 year life outdoors. -john On Feb 6, 9:07 am, JJ Sinclair wrote: I second the L-2, di-pole antenna suggestion, all inside with nothing sticking out to get ripped off. Carve a1"X 1"X4" balsawood block so that it matches the inside curve of your non-carbon fuselage, then glue the antenna vertical to the flat side and the curved side to the inside aft fuselage. *Keep it about 6" away from metal objects like your elevator push-rod, etc. Secure the RG-58 lead so that it can't get tangled with controls and you're good to go. Hope this helps, JJ- Hide quoted text - - Show quoted text - The Becker 4401-175 manual does say that RG-223/U is preferred over RGU-58, but it doesn't mention LM-240? As a mechanic I am bound to follow the appropriate tech data. Does LM-240 use the same BNC fittings I have in stock? Can I use my crimper? What would my log book entry say? Installed Becker 4401-175 transponder in accordance with opinions found on ras? :) JJ 'Aircell 5' is a good substitute for plain vanilla RG 58/U coax cable. It fits standard BNC connectors. Attenuation at 1000 MHz is about 32 dB/100m (compared to 54 for RG58) Willy VINKEN -ON5WV- |
#18
|
|||
|
|||
Transponder antenna installations
On Feb 7, 7:46*am, Willy VINKEN wrote:
On Mon, 7 Feb 2011 06:18:57 -0800 (PST), JJ Sinclair wrote: On Feb 6, 9:57*am, jcarlyle wrote: JJ, please don't use RG-58 for a transponder cable - it has very high attenuation per foot. Times Microwave LM240 is a much better choice, with only 1/3 of the attenuation of RG-58 at 1 GHz. I usually use Times Microwave LM300, with only 1/4 the attenuation of RG-58, but it has double the diameter. Both of these cables have a greater than 20 year life outdoors. -john On Feb 6, 9:07 am, JJ Sinclair wrote: I second the L-2, di-pole antenna suggestion, all inside with nothing sticking out to get ripped off. Carve a1"X 1"X4" balsawood block so that it matches the inside curve of your non-carbon fuselage, then glue the antenna vertical to the flat side and the curved side to the inside aft fuselage. *Keep it about 6" away from metal objects like your elevator push-rod, etc. Secure the RG-58 lead so that it can't get tangled with controls and you're good to go. Hope this helps, JJ- Hide quoted text - - Show quoted text - The Becker 4401-175 manual does say that RG-223/U is preferred over RGU-58, but it doesn't mention LM-240? As a mechanic I am bound to follow the appropriate tech data. Does LM-240 use the same BNC fittings I have in stock? Can I use my crimper? What would my log book entry say? Installed Becker 4401-175 transponder in accordance with opinions found on ras? :) JJ *'Aircell 5' *is a good substitute for plain vanilla RG 58/U coax cable. It fits standard BNC connectors. Attenuation at 1000 MHz is about 32 dB/100m (compared to 54 for RG58) Willy VINKEN *-ON5WV-- Hide quoted text - - Show quoted text - ....and Aircell 5 IS listed in the manual for the Trig transponders. RG-58 is not. |
#19
|
|||
|
|||
Transponder antenna installations
Trig is probably “fussy” because they think you should deliver the
transponder power to the antenna, not use it to heat the cable. I think it's significant that Trig doesn’t specify the use of RG-58 at all. Aircell cables are European, they aren’t easily available in the US, and would be expensive if you could order them. Attenuation for Aircell 7 (the best cable recommended by Trig) is 6.9 dB per 100 feet at 1 GHz. US made LMR300 is even better, it has an attenuation of 6.4 dB per 100 feet at 1 GHz. LMR240 comes in with a bit higher attenuation at 8.0 dB per 100 feet at 1 GHz. As for cost, 15 feet of bare LMR240 is $13.35. You can get a complete LMR240 cable made with a TNC at one end and a BNC at the other for only $30. Doesn’t seem outrageous. -John On Feb 6, 10:55 pm, "Paul Remde" wrote: Hi, The Trig TT21 and TT22 manual is also quite fussy about transponder antenna cable. But it important to note that many of the "long run" antenna cables they recommend are extremely expensive. I recommend mounting the transponder unit (it is separate from the control head) as close to the antenna as possible. When that is done I have received customer feedback that RG-58 cable works fine - with all required tests passed with flying colors. Paul Remde |
#20
|
|||
|
|||
Transponder antenna installations
On Feb 7, 3:27*pm, Grider Pirate wrote:
On Feb 7, 7:46*am, Willy VINKEN wrote: On Mon, 7 Feb 2011 06:18:57 -0800 (PST), JJ Sinclair wrote: On Feb 6, 9:57*am, jcarlyle wrote: JJ, please don't use RG-58 for a transponder cable - it has very high attenuation per foot. Times Microwave LM240 is a much better choice, with only 1/3 of the attenuation of RG-58 at 1 GHz. I usually use Times Microwave LM300, with only 1/4 the attenuation of RG-58, but it has double the diameter. Both of these cables have a greater than 20 year life outdoors. -john On Feb 6, 9:07 am, JJ Sinclair wrote: I second the L-2, di-pole antenna suggestion, all inside with nothing sticking out to get ripped off. Carve a1"X 1"X4" balsawood block so that it matches the inside curve of your non-carbon fuselage, then glue the antenna vertical to the flat side and the curved side to the inside aft fuselage. *Keep it about 6" away from metal objects like your elevator push-rod, etc. Secure the RG-58 lead so that it can't get tangled with controls and you're good to go. Hope this helps, JJ- Hide quoted text - - Show quoted text - The Becker 4401-175 manual does say that RG-223/U is preferred over RGU-58, but it doesn't mention LM-240? As a mechanic I am bound to follow the appropriate tech data. Does LM-240 use the same BNC fittings I have in stock? Can I use my crimper? What would my log book entry say? Installed Becker 4401-175 transponder in accordance with opinions found on ras? :) JJ *'Aircell 5' *is a good substitute for plain vanilla RG 58/U coax cable. It fits standard BNC connectors. Attenuation at 1000 MHz is about 32 dB/100m (compared to 54 for RG58) Willy VINKEN *-ON5WV-- Hide quoted text - - Show quoted text - ...and Aircell 5 IS listed in the manual for the Trig transponders. RG-58 is not. We use RG 400 for our transponder antenna cables. Trig says it is good for up to 8'4".....(So does Garmin.) Since you can mount the trig transmitter box wherever you need, staying less than 8' is easy. Cookie |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Transponder Antenna | Rick Fuller | Soaring | 6 | January 30th 08 06:03 PM |
Transponder Antenna Location | [email protected] | Soaring | 15 | January 17th 08 06:56 PM |
VHF & Transponder antenna | Steve | Home Built | 1 | December 6th 04 04:29 PM |
Oil on transponder antenna | Bob | Owning | 12 | May 9th 04 08:59 PM |
Transponder and antenna | Paolo | Soaring | 1 | March 6th 04 03:32 AM |