VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.


Go Back   VAF Forums > Avionics / Interiors / Fiberglass > Autopilots
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #21  
Old 05-24-2022, 07:41 AM
Dandlac58's Avatar
Dandlac58 Dandlac58 is offline
 
Join Date: Oct 2021
Location: Sierra Vista
Posts: 44
Default

Quote:
Originally Posted by Carl Froehlich View Post
Dan,

Just give me a call and we’ll discuss.

Carl
Hi Carl,

Will call you this afternoon.

Thanks

Dan
__________________
Dan L
N327CD
2004 RV7 and RV7A (birthed as a 7A, then 7 from 2006 until this past October and now RV7A again - has all mounts, gear, brake plumbing for both configurations)
Reply With Quote
  #22  
Old 05-24-2022, 07:59 AM
Dandlac58's Avatar
Dandlac58 Dandlac58 is offline
 
Join Date: Oct 2021
Location: Sierra Vista
Posts: 44
Default Morning Update, 24 May 22

Hi Bob,

There are no schematics for how this panel is put together, so I am essentially learning it as I go.

There are no individual circuit breakers on the panel for the individual NAVCOM devices, the transponder, etc. What there is, is a Master Avionics Breaker which feeds to two "submaster" Avionics breakers which then each provide power to different pieces of the stack. The TT A/P is on its own separate circuit breaker - go figure!~

I cannot say for a fact, yet, that there are not fuses on the power lines going to each device.

I have now discovered that there is RG58 coax for the COM radio on the GNS430W and it terminates in the tail cone on a ratty horizontally polarized antenna... the coax has a severe bend in it at the rear of the fuselage as it leaves the belly and transitions up to where the antenna is mounted. I am having my A&P fabricate a test coax of RG400 which I will use first to test continuity of the current RG58 shield and center conductor and then to replace the RG58 and make a quick run directly between the radio and antenna mostly outside of the aircraft, away from all other power and signal lines to see if it clears the problem on the TruTrak.

Notes of interest:
a. The cable for the GSN430W GPS antenna is RG400.
b. The cable for the GNS430W Nav is RG400 and goes to a splitter which then goes to the Comant CI122 antenna mounted on the belly.
c. The cable for the GNS430W G/S connector goes to the other connector on the splitter (it is a 2 down to 1 splitter) and so therefore goes to the Comant on the belly.

Apparently the SL40 coax goes to an antenna in one of the wingtips, something which I must visually prove!

More to follow.

Thanks

Dan


Quote:
Originally Posted by BobTurner View Post
Side issue: Did you say that the wiring to your radios is not protected by CB s or fuses? That doesn’t sound good. But for Carl’s test, turning them off with their on-off switch should be okay.
Main issue: Are you saying you have not yet examined the coax connectors? Both radio end and antenna end? IMHO corrosion is often the root source of avionics problems. I still recall fixing an ARC autopilot by simply unplugging, and re-plugging, its connector in the wing. (Unplugging/re-plugging tends to scrape off a thin layer of corrosion. I would recommend getting hold of some spray-on contact cleaner, take apart every connection you can find (autopilot too) and spray it, re-assemble. These problems can be insidious, very hard to spot.

The SL30 is IMHO the best nav-com ever made. Unfortunately they have not been manufactured in many years, so they’re getting a bit long in the tooth.
__________________
Dan L
N327CD
2004 RV7 and RV7A (birthed as a 7A, then 7 from 2006 until this past October and now RV7A again - has all mounts, gear, brake plumbing for both configurations)
Reply With Quote
  #23  
Old 05-24-2022, 12:33 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,218
Default

Quote:
Originally Posted by Dandlac58 View Post
Hi Bob,

There are no schematics for how this panel is put together, so I am essentially learning it as I go.

There are no individual circuit breakers on the panel for the individual NAVCOM devices, the transponder, etc. What there is, is a Master Avionics Breaker which feeds to two "submaster" Avionics breakers which then each provide power to different pieces of the stack. The TT A/P is on its own separate circuit breaker - go figure!~

I cannot say for a fact, yet, that there are not fuses on the power lines going to each device.

I have now discovered that there is RG58 coax for the COM radio on the GNS430W and it terminates in the tail cone on a ratty horizontally polarized antenna... the coax has a severe bend in it at the rear of the fuselage as it leaves the belly and transitions up to where the antenna is mounted. I am having my A&P fabricate a test coax of RG400 which I will use first to test continuity of the current RG58 shield and center conductor and then to replace the RG58 and make a quick run directly between the radio and antenna mostly outside of the aircraft, away from all other power and signal lines to see if it clears the problem on the TruTrak.

Notes of interest:
a. The cable for the GSN430W GPS antenna is RG400.
b. The cable for the GNS430W Nav is RG400 and goes to a splitter which then goes to the Comant CI122 antenna mounted on the belly.
c. The cable for the GNS430W G/S connector goes to the other connector on the splitter (it is a 2 down to 1 splitter) and so therefore goes to the Comant on the belly.

Apparently the SL40 coax goes to an antenna in one of the wingtips, something which I must visually prove!

More to follow.

Thanks

Dan
A few thoughts:

1. Hopefully the builder understood that every wire downstream of the breaker must be able to carry the full breaker current limit. That means the individual wires to the avionics must be larger than normally used.
2. Hopefully your com antenna is vertically polarized, not horizontal.
3. Look at the connectors for any corrosion. Rule 1 of trouble shooting: always do easy stuff first, even if unlikely.
4. Coax with a sharp bend is asking for trouble, now or later. RG400 is relatively expensive, so save a few dollars and rather than have your mechanic fab a test piece, just replace the RG58 now.
5. Your ‘splitter’ (which technically is a simple 1 into 2 device) is probably a ‘diplexer’ (which splits 100 MHz into one output, 300 MHz into the other). The difference is rarely important except for distant VORs. But check that the connections are correct (antenna, VOR/LOC, GS to the corresponding antenna and 430 inputs)
6. The wingtip com antenna must also have as much vertical throw as possible in its leading edge, or performance will be poor.
Reply With Quote
  #24  
Old 05-30-2022, 10:59 PM
Dandlac58's Avatar
Dandlac58 Dandlac58 is offline
 
Join Date: Oct 2021
Location: Sierra Vista
Posts: 44
Default Ive got the airplane all apart now...

Hi Bob, Carl, Andrew,

... with both wingtips off, floor panels out, rear bulkhead covers removed... so I can start replacing cables.

Priority 1:
a. Replace GNS430 Com RG400 Cable to new RG 400 and install on Comant Vertical polarized Antenna on belly.
b. Replace RG58 cable running from the GPS connector on the GNS 430 to the GA35 GPS antenna on the top of the fuselage.

Priority 2:
a. Add a stand alone circuit breaker to the Uavionix Echo ADSB In/OUT box so I can independently control power to it instead of powering it with one of the Avionics Masters as it is currently configured. This way I can check and see if either the ADSB 978 Mhz Out or the WIFI to my IPAD is causing any EMI. The Echo was added by the previous owner as part of the purchase agreement and it wasn't really installed up to standard of Part 43.
b. Replace the RG58 with RG400 on the SL40 and add a new antenna on the fuselage to replace the hokey one in the wingtip.

Priority 3: Before resuming flight, run new RG400 from ELT to antenna to replace the bad RG58. Replace batteries in ELT.

I haven't heard from Andrew as to the possible causes why the TT A/P is displaying the heading compass degrees rising by up to 17-19 degrees just because I am keying the radio. As soon as I stop keying the displayed degrees goes back to where it was before keying the mike. Im hoping changing out all these cables and re-routing them will solve it.

Dan
__________________
Dan L
N327CD
2004 RV7 and RV7A (birthed as a 7A, then 7 from 2006 until this past October and now RV7A again - has all mounts, gear, brake plumbing for both configurations)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 11:00 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.