Coax Connector Question

I want to prewire the wings so that when the times comes to mate them to the fuselage all I'll have to do it make a few electrical connections at the wing root. This plan also includes a disconnect for the RG58 coax run to a Bob Archer wingtip VOR antenna.

This is my question: Is it acceptable to drill a hole through the inboard wing rib to accept a connector as shown...a type which is used to connect two coax cables together....thus in this application essentially becoming a "bulkhead" connector? Certainly, it is better to have a continous, unbroken run to the radio if possible but if coax performance and VOR reception is not degraded in any MEANINGFUL way, for the sake of convenience I would prefer to go this route. Thoughts?

Use an insulated (isolated) connector

Rick... each connection may loose a little signal, but it's down in the noise level for our application. One extra connection will not be noticeable.

However, the grounding point of the Bob Archer antenna may be critical (I'm not sure), so the safest bulkhead connector to use would be an insulated (aka isolated) bulkhead one....

http://www.mpja.com/prodinfo.asp?number=5435+RC

gil A

Thanks Gil. I was a bit concerned about potential grounding issues....just to be on the safe side, the bulkhead connector in your link looks to be the way to go.

Impedance

Rick,

There is loss when you use disconnects. That being said, the loss at the frequencies we are talking about are negligible, in fact, we use disconnects routinely where I work (major completion center for Bell Helicopter) with no ill effects. BUT the connector you show in the picture is a TV cable connector (75 ohm) you need a proper BNC bulkhead connector (50 ohm) that you can buy from aircraft spuce. I'd say go ahead and install one, it won't hurt the preformance of the system, but choose the correct connector.

Rick, I did what you are planning.

I used a standard RCA bulkhead connector on the fuse side at the wing root. It is grounded to the fuse, no problem with the Bob Archer NAV ant.

Kent

Use a BNC bulkhead connector to maintain the proper impedance and also to be sure of a proper ground and mechanical connection. The RCA plug is a poor connector to use. My opinion anyway.

You?ll be fine with a bulkhead connector, but my personal preference is to run a continuous cable from the radio to antenna. During construction, leave it coiled in the fuselage and leave a pull string in the wing. When the wings are joined, pull the cable through. If you ever need to remove the wings, a bulkhead connector can be added at that time. Few RVs have their wings pulled off after completion.

Benefits from this include:
1. Slightly lighter, every ounce adds up

2. Less time for installation

3. Less signal loss (minimal benefit)

4. Four less joints (cable to connector X 2 plus connector to bulkhead fitting X 2) Any time a joint is added, you add the potential for issues at a later time. This will add another area that must be included in any troubleshooting that may be needed. This will require the removal of inspection panels and the wing root fairing.

5. The bulkhead fittings are in the wing root, the wings have a positive dihedral, water can work its way down there, see item #4 above.

I just can?t see the need to install the bulkhead fitting during construction.

Just my $.02

Woops...

Norman CYYJ said:

Use a BNC bulkhead connector to maintain the proper impedance and also to be sure of a proper ground and mechanical connection. The RCA plug is a poor connector to use. My opinion anyway.

Click to expand...

I meant BNC, but my fingers typed RCA.

Hey, it is three letters, so I think that I did pretty good.

Kent

My oops....

kentb said:

I used a standard RCA (updated to BNC) bulkhead connector on the fuse side at the wing root. It is grounded to the fuse, no problem with the Bob Archer NAV ant.

Kent

Click to expand...

Rick... I misread your original post.... I was thinking of the outboard rib...

A ground at the root rib should have no significant effect, as Kent has proven, however, an insulated one will do no harm either...

gil A - back to reading/comprehension class....

I was planning on using a BNC female connector (see second item at http://www.steinair.com/connectors.htm) on the wing root end of the cable in the wing and mating that up to a male connector on the coax from the radio.

Rick,
You can get a bulkhead connector of the correct type from www.tessco.com . I just bought one for my -4. Try part number 99684, which is insulated from the bulkhead, or 47401 which is not insulated and comes with a O-ring. You'll have to call them to place an order but they deliver quickly.

Alan
RV-4

ABRV4 said:

Rick,
You can get a bulkhead connector of the correct type from www.tessco.com . I just bought one for my -4. Try part number 99684, which is insulated from the bulkhead, or 47401 which is not insulated and comes with a O-ring. You'll have to call them to place an order but they deliver quickly.

Alan
RV-4

Click to expand...

Thanks Alan. I was going to order the connector from Spruce but surprise surprise....the isolated bulkhead connectors are currently on backorder. Other sources of supply required a minimum dollar order amount. As it happens, I subsequently found and purchased a package of 5 female (isolated) bulkhead connectors for $6 on eBay.