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Can I shorten the cable on a new Digital antenna?

Started by Markshoreline, April 18, 2017, 06:01:46 PM

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Markshoreline

I have pulled out the old crappy antenna mounted to the side of the cab and bought a new Digital brand to mount up on the roof rail to get better range.  I don't need the excess cable, how can I shorten it since the end is factory installed?
How would I know the optimum length to trim it to, as GregE suggests tuning it by cable length?
2002 Sea Ranger HT 21, Yamaha 150, Yamaha 9.9

GregE

Also, antennae wire length is part of the tuning.  Check before cutting......
Greg
2005 SL 22 Honda 225 Kodak II
http://www.sagecreekforums.com/phpforum/index.php
Sold:Osprey 26 LC Kodak;  Arima SR 19 HT, Arima SE 16 WeeBait; SH 15 WeeBoat; SR 21 NoBait;  SL 22 ReBait

fishmiester

Mark: Is there any way you can coil up the excess cable and tuck it out of the way? I would not recomend cutting the cable to shorten it. I am not familier with the digital antenna, but normal vhf antennas rely on the length of the cable to keep the vswr down thus keeping the antenna tuned. Maybe Streamfixer will chime in on this and can explain it better.
If it swims, Ill  chase it
84 17' Seachaser, 2010 90hp Tohatsu tldi, BF15 Honda Custom welded kicker bracket.#lovethisboat

Markshoreline

Yep, I've got lots of cables coiled up in the boat!  I could do this one, too If I need to.
2002 Sea Ranger HT 21, Yamaha 150, Yamaha 9.9

croaker stroker

1987 - 17' Sea Pacer - 2004 Evinrude 90 E-tec
1985 - 15' Sea Sprinter - **SOLD**

"Ex Tridente Pax". 🇺🇸

DevMah

#5

We don't cut them but roll them up as they use low loss cable on the digital antenna.

The cheaper fibres glass ones don't have the ends connected, so we usually pull the cable and leave a few feet coiled up.


Dev.

2015 21' Sea Ranger w 150 Yammy  (Tight lines) Sold
2012 Lund 1650SS  w 2012 60HP Mercury-Sold

Threeweight

Digital-brand antennas are tuned to the length of the cable they ship with.   If you want to match the factory performance after your cut it, it has to go to an electronics shop with a SWR meter and have it re-tuned.

Plus if you cut it, you lose the sweet gold-plated connector Digital uses, and will have to install a crappy Shakespeare crimp-on or solder-on which is much more prone to problems.

Do not coil it into a tight circular pattern either, if you can avoid it.  Coil the excess in a messy figure 8 pattern, or if you must loop make the loops large (like 12+ inches) and a little random/messy in size.  Tight coils distort the cable and cause impedance.

Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

Markshoreline

OK, thanks- I'll save some trouble and hopefully have a better performing antenna!

Quote from: Croaker Stroker on April 18, 2017, 07:11:28 PM

Did you read the Digital antenna instructions?

Croaker, you are beginning to sound like my wife...   :jester:
2002 Sea Ranger HT 21, Yamaha 150, Yamaha 9.9

croaker stroker

1987 - 17' Sea Pacer - 2004 Evinrude 90 E-tec
1985 - 15' Sea Sprinter - **SOLD**

"Ex Tridente Pax". 🇺🇸

Markshoreline

I thought so- that was such an inappropriate question!   :jester:
2002 Sea Ranger HT 21, Yamaha 150, Yamaha 9.9

StreamFixer

Mark (and others with excess antenna coax  length)

Do not coil the extra antenna feed coax.  Doing so creates a 'choke' that modifies the antenna tuning.  Rather than coiling the excess, I suggest you run it back and forth to use up the length, or just about any other form except a coil.  If you must coil it, try to stay at about a foot diameter (or larger).  If you MUST make smaller coils, don't have more than three coils at any given point.  For example,  Three coils just inside the wall, three coils a couple of feet away, three coils at the back of the radio.  Maximum 2 coils even better


StreamFixer
'01 Hewes Sportsman 18
'14 Yamaha 90
'01 T8 w/ solas 4 blade
'19 Minn Kota 80# (Alterra)
'97 19SC w/ Salt Boss Top


"By the grace of God we travel upon the rivers and sea..
They, like He, are mightier than me."  Mike Jesperson aka 'Nalu

Yachter Yat

   I thought about getting one of these some time ago.  From what I read, it sounds like a PITA.   Guess I'll keep my old Shake.

Yat
History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

Threeweight

No more a pain than your old Shakespeare.  If you left the Shakespeare cable full length, the Digital would have greater signal clarity and range, plus much sturdier construction.  If you cut it and crimped or soldered the cable, the Digital would have MUCH greater signal clarity and range, plus sturdier construction. 
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

Markshoreline

I'm happy to coil.  Any issues with coiling next to other coils?
2002 Sea Ranger HT 21, Yamaha 150, Yamaha 9.9

Yachter Yat

   Threeweight;   I've been running my Shakespeare 5225 for years with (what I think, at least) a fair amount of success.  That said, you might be talking me into this.  Given what I'm reading, I'd be leaning toward cutting that cable.  Gonna have to do a little more research on this, I guess.  These days, it's like, any equipment I contemplate changing seems to be a bit more complicated than the original.  Oh well.......looks like I'll be going for my Doctorate in antenna technology.  :jester:

Yat
History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

StreamFixer

Quote from: markshoreline on April 20, 2017, 11:39:50 PM
I'm happy to coil.  Any issues with coiling next to other coils?

Keep a foot or so between the coils, otherwise you might as well just make one coil and accept the signal loss.  PITA, I know, but that is the way antenna systems work.

StreamFixer
'01 Hewes Sportsman 18
'14 Yamaha 90
'01 T8 w/ solas 4 blade
'19 Minn Kota 80# (Alterra)
'97 19SC w/ Salt Boss Top


"By the grace of God we travel upon the rivers and sea..
They, like He, are mightier than me."  Mike Jesperson aka 'Nalu

Yachter Yat

   Hey guys;  I believe I asked this once before, but still wonder if this antenna could be ordered from the factory with a specific cable length and tuned accordingly?? :shrug9:  If this could be done, I'd be very interested.

Yat
History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

ak-angler

For those on the fence... I absolutely love the Digital antenna I installed on my Cape Cruiser. Reception is orders of magnitude better than I had with my previous Shakespeare antenna (don't know the model #). As far as dealing with the excess cable length goes (I know this probably won't help on most Arimas), I strung it back and forth in kind of a lazy figure-8 pattern, probably about 4-5 feet long, on the shelf above the window. Maybe it would work to loosely attach the excess up under one of the shelves on the sides of the cabin with a few of those zip-ties that have mounting holes? Just screw them to the bottom of the shelf and secure the cable up out of the way. Maybe...?
1985 Sea Ranger 17 Skiff Top with 2012 Suzuki DF90A - Sold

2007 Cape Cruiser Marinaut 26 with twin 2006 Honda BF90's

croaker stroker

#18
I agree with AK. My new digital seems to work great without cutting. I also hanked my excess wire in three foot figure eights and zip-tied.

(Shall I mention again how much the Standard Horizon amplified speaker helps with reception of (hearing) weak signals ?).  The speakers in most VHF radios suck.

Back in the day, I always matched my antennas using an SWR meter. Took a while by cutting one inch off the wire, soldering the connector, then checking the SWR. Then repeat until you reach a satisfactory reading. If I remember correctly, the wave length was about 36 inches ? (Been a long while)

So many posts on the internet saying that this is un-necessary these days because of advancements in the newer radios....??  (Then why does Digital recommend not cutting the cable.).  :shrug9:
1987 - 17' Sea Pacer - 2004 Evinrude 90 E-tec
1985 - 15' Sea Sprinter - **SOLD**

"Ex Tridente Pax". 🇺🇸

Threeweight

Yachter, you could be anal like me and run 2 vhf fixed mount radios.  When I haggled on my new boat, I got the dealer to throw in an cheap Cobra radio + Shakespeare antenna.  It is now my backup, mounted up to one of my overhead shelves and stays tuned to the local fishing channel.  My Standard Horizon + Digital 529 combo is my main, mounted to my dash and tuned to scan 16+22+commercial traffic.
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

Yachter Yat

   Threeweight;   I guess it was the first line of your post (suggesting these antennas were tuned to the cable they're shipped with) that got me wondering whether or not they could be special ordered, tuned to a specific cable length.  I suppose the best way to find out is to go directly to the manufacturer.   BTW, I've always been a big Icom fan boy.  Still running my old M56 from 1994.  Seems to be holding out okay...........knock on wood.  :biggrin:

Yat
History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

Threeweight

Icom makes great stuff.  Check out the helm of any Coast Guard, commercial fishing, search and rescue, etc... boat, and the radio will be Icom.

I like Standard Horizon because they are a bit cheaper, and they have a stellar reputation for standing behind their products.  They also tend to roll out new technology a little bit quicker.  Their GX 1700, with it's built in GPS unit and DSC function in a super tiny package, is ideal for cramped Arima dash space.
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson