[Supercat]

Hello all,

Whilst putting my Jodel back together I've reached a decision point.
1. Once the wing is back on there is no real access into the rear fuselage, so no access to the antennas.
2. There is only 1 official hole through which to route 1 X Com coax, 2 X PaW coax and 1 X Transponder coax.

I'm sure I've read that they shouldn't be routed together due to cross-talk, so my questions are:

Is there anything I can do to make it possible to route them together? Some kind of earthed shielding?
Drill 1 extra hole for the Com coax?
Drill 2 extra holes, 1 for Com 1 for Transponder? (As PaW is lower powered could they both be run together?)

Obviously I really want no extra holes, but not being versed in Radio theory I don't know what the best approach will be.

So if you're out there and know the answer I'm all ears.

Thanks.

[Flyingmac]

I don't know which Model you have, but my Jodel had an inspection panel on the underside of the fuselage. Big enough to get head and shoulders through. Easy access to Comms antenna (top) and Transponder antenna (bottom).

Keep the Comms coax away from anything else. I have no experience of PAW.

[Flying_john]

Good Quality Co-Ax aerial cabling is inherantly screened, so one hole is fine.

[Hanworth]

Good Quality Co-Ax aerial cabling is inherantly screened, so one hole is fine.

Yes. Good quality coax, good quality connectors well installed, and antennas well mounted. That should be fine,

[Shoestring Flyer]

You need RG400 co-ax for use in an aircraft. Not cheap but using anything else of a lower grade will, nine times out of ten, give you interference problems.
RG400 used in close proximity or routed along side with whatever you are connecting with RG400 will not be a problem at all.

[Hanworth]

You need RG400 co-ax for use in an aircraft. Not cheap but using anything else of a lower grade will, nine times out of ten, give you interference problems.
.

https://www.parts4aircraft.com/rg58-and ... coax-cable

RG400 is MIL spec stuff and priced accordingly. Maybe a bit overkill tbh? If you are going to use it, you need quality connectors too to avoid wasting the money. Mind you, you don't need many metres for aircraft installations.
Personally I've never had a problem with RG58 as long as it's properly installed.

[Nick]

If you wish to do a first class job, start with first class parts. It will be quicker and better in the long run, if you do right first time. I was always taught, "Do it right do it once".

Nick

[tnowak]

I don't believe RG400 is a "military" spec. cable; it just has better performance than RG58.
Compare the specifications and you will see (attenuation/frequency loss etc.).
RG58 will work okay in most situations, but RG400 is a higher performance cable...

[Sooty25]

You probably want to use RG400 for PAW and Transponder antennas regardless due to the much lower attenuation at the higher frequencies used.

There's also the temperature ratings to consider, RG58 is PVC and PE construction, whereas RG400 is PTFE so less likely to cause further issues in the event of a panel fire.

Just use RG400 for all of them, but, the P4A pricing is borderline criminal, look elsewhere.

[Hanworth]

All true @Sooty25 , and you pays your money and takes your choice of course. Given the short cable lengths the quality of the connectors and how well they are installed will be more significant to attenuation relatively speaking - it's important not to short change yourself there - I do want to emphise this point as its too often forgotten.

[Supercat]

Thanks for the replies everyone.

RG400 and Amphenol brand connectors it is.

[Boxkite]

Some connectors require expensive crimping tools, you might want to avoid those.

[Paul_Sengupta]

LMR400 is a fairly hefty cable. If you want to save a bit of weight, this is also good quality.

https://messi.it/en/catalogue/50-ohm-cables-ham-radio/airborne-10.htm

Claims "Incredible lightness: 45% lighter than average 10,3mm cable"

Though actually LMR400 is also copper coated aluminium so it might be a similar weight.

Going down to 7mm rather than 10.3mm there's this:

https://messi.it/en/catalogue/50-ohm-cables/ultraflex-7.htm

If you wanted something the size of RG-58 there's this:

https://messi.it/en/catalogue/50-ohm-cables-ham-radio/airborne-5.htm