Wiring and it's effects on signal quality

Chorky

Observer
Lets talk wiring. I'm sure everyone has gone through the struggle. You have a new radio, its installed, you want to mount the antenna....but how/where do you route the cable??

Many opt to either run through a existing hole in the firewall, while others just run through the door seal, and some make their own hole. But what if you want to make for connections in the event that at some point the vehicle (a truck) needs to be worked on and that work happens to require removal of either the cab side wire, or the antenna side wire.

So the thought would be something like this. Run a cable from the radio to a grommet that exists the vehicle. Add a splice connector, adn then run a second cable from that connection to the antenna (which will be mounted on a canopy).

This would allow for, say, the bed (or cab) to be removed with simple disconnection of the cable rather than pulling the entire cable back.

The question; however, is what effect will this have (if done correctly) on signal, or will it have minimal effect??
 

Joey G

Member
It will have minimal effect if done properly. Every connection causes some amount of loss and creates an opportunity for noise to enter, but the mobile environment is full of compromises anyway. I’d do it in a heartbeat if it added some convenience.
 

DaveInDenver

Expedition Leader
What you're after is a bulkhead connector. There's many different connectors out there and the one most U.S. hams use is the SO239/PL259. You could use a SO239 bulkhead, terminal the antenna with a PL259 connector and make a dual PL259 patch cable for inside.

Thru-bulkhead-connection_mid.jpg

It's not a zero impact to the signal quality but for CB up to VHF this can be reasonably low loss. For UHF (70cm or GMRS for example) this wouldn't be an ideal because each SO239/PL259 measurably degrades your signal.

My $0.02 for amateur use I'd personally use a BNC or N (they look like the ones below) bulkhead and just terminate the inside in a PL259 if that's what your radio uses. These connectors were designed about 20 or so years after the PL259/SO239 type and work with low loss out to a couple of GHz.

n-macho-bnc-hembra_mid.jpg
 
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Chorky

Observer
Perfect! I was thinking something a little different but this is probably even the better way to go. Thank you Dave!

FYI I would be using this method for CB, GMRS, 2m/70cm, cell extender, and a scanner as all antennas are planned to go on the truck canopy.
 
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Verkstad

Raggarkung
If you dont want a rigid excess space consuming passthru device...
Nothing wrong with simply pass coaxcable thru whatever the barrier is and fit an appropriate female/male connector to join them.
Some may claim one method is cleaner or not, but it does reduce by one splice connection.
What you're after is a bulkhead connector. There's many different connectors out there and the one most U.S. hams use is the SO239/PL259. You could use a SO239 bulkhead, terminal the antenna with a PL259 connector and make a dual PL259 patch cable for inside.

View attachment 537371
 

DaveInDenver

Expedition Leader
If you dont want a rigid excess space consuming passthru device...
Nothing wrong with simply pass coaxcable thru whatever the barrier is and fit an appropriate female/male connector to join them.
Some may claim one method is cleaner or not, but it does reduce by one splice connection.
There are indeed many ways around it. A free-hanging connector with a grommet through the bulkhead or a coax-terminated bulkhead would save at least one connector.

Coax-box-fitted-to-wall_mid.jpg

heycoroofwiring5.JPG
 
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DaveInDenver

Expedition Leader
You could just use a plain panel mount connector.

s-l1000_mid.jpg

Also, for free hanging connectors Amphenol (and maybe others) make a hood to convert the standard (e.g. cheap) panel-mounted SO239 into an inline with the back side protected.

83-765.jpg


It'll look like this when made up. This appears to be an N type made into an inline with an SO239/UHF on the chassis itself.

mvpback.jpg
 
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Chorky

Observer
Hmm...so many ways. maybe i should make a 'coms connection' panel where all the coms cables have a connection spot on, say, a 4" x 4" alum panel, then do a cut out of the truck body, and attach the panel, that way it's also modular in the future if something needs to be added or changed? It could be difficult to seal though to prevent water intrusion into the truck cab though.
 

Billoftt

Active member
Maybe an SMA bulkhead connector. They are pretty small, unobtrusive and they have low loss up to what, 18GHz.

On a side note, what is up with North America's obsession with the PL-259/SO-239? Even the EU versions of the same radios we have here use N-Type. I was actually thinking about taking my Kenwood and my two Midland GMRS radios and converting them to N-Type but it seems N-Type female chassis connectors are on perpetuaonbackorder.


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DaveInDenver

Expedition Leader
N-Type but it seems N-Type female chassis connectors are on perpetuaonbackorder.
Bet if you look around you can find a couple. Mouser currently has stock of both 2 hole flange type (Amphenol 17232) and 4 hole type (Amphenol 172119), for example.


 

Billoftt

Active member
Yeah, so this is what is in the chassis of the Midland Micro Mobile series.


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Billoftt

Active member
I was actually on Mouser's site looking at the drawings when you sent this.

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