| [GMCnet] radio antennae [message #280284] |
Fri, 19 June 2015 13:15  |
mjbourgon
Messages: 259
Registered: May 2010
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Okay you guys, put on your thinking caps. Working on by Glennbrook.
Ceiling has completely been removed and getting ready for radio
installation. I am going to install a new antennae in roof and would
like to make sure it is properly installed. Last time it seemed to work
fine but could not get A.M. reception. I need some ideas of the best
way to install a new anttenae so I can get good f.m. and good a.m.
Thanks guys appreciate the ideas
Marcel in Santa Teresa, N.M.
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| Re: [GMCnet] radio antennae [message #280293 is a reply to message #280284] |
Fri, 19 June 2015 14:39  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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OK, first of all, make sure the radio in question even has decent AM reception - the majority of current offerings do not. Assuming it does, anyone's 31 inch continuously loaded whip ought to work. HOWEVER, put the biggest piece of tin on the underside of the fiberglass you can get to fit. Run a piece of braid from it down the center post and bolt it to a decent ground. (This will also allow a CB antenna to work properly when mounted up there). Depending the radio, there should be an AM trimmer which is screwdriver adjusted. Follow the instructions to set it, if there aren't any, tune a station around 1500 and turn the trimmer for best reception.
I have to warn you, today's AM receivers sound like hammered dog poop for the most part. I had a long conversation with a Delco engineer at a broadcaster's convention about this. The then current top of the line Delco had an AM response out to perhaps 3KHz, the 3dB points being about 3500 Hertz. I ask the guy why they produced such shit response. He said they dropped the better AM response when they found dealers installing aftermarket radios in Cadillacs and Oldsmobiles. Seems Ms. Bigbux was disenchanted by the hiss and noise which has now become the standard accompaniment to AM sound. Their position was, we sell radios in our cars. We sell what the buyer wants to hear, and if that's very restricted audio response, that's what we will build.
Find a Chrysler Huntsville AM radio with Kahn AM stereo reception in it at a man's mall and use it. Get someone to modify it so that it thinks it's receiving stereo. This opens the bandwidth nicely and shows you the response AM is capable of, assuming the station is up to snuff. Kahn used a 5Hz pilot tone to indicate stereo was in operation. We ran a 5Hz tone at low level on our Syracuse station (WSYR) back then, and Chrysler and aftermarket Kahn radios sounded marvelous. Leonard (Kahn) found out about it and sent a Cease And Desist. since we weren't using his stereo system. Our mouthpiece sent him one back quoting the Rules, none of which precluded what we were doing, and told him to go pack sand. If anyone gets near Syracuse, it would be interesting to see if that tone is still there. Kahn stories are legion in my profession, the guy was an absolute genius. He had exactly zero social skills, which didn't help him in the business world.
Chrysler fitted some of the best auto radios ever built at the time, mostly because Chrysler Aerospace Electronics division was a mil spec shop which mostly built what Von Braun told them to build. Even modified for assembly line production quantities, they were golden.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] radio antennae [message #280323 is a reply to message #280284] |
Sat, 20 June 2015 04:05 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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The center mounted top of the coach location that GMC used was a good location. The antenna is mounted in the aluminum portion of the roof good giving the antenna a very good ground plane and good omni-directional reception. Unfortunately over the years that location tended to oxidize and the ground connection at the base of the antenna mount became intermittent or electrically non-existent. I would reuse that location for your new antenna and clean up the underside of the aluminum roof where the antenna mount touches the aluminum I would also coat the underside mounting area with anti-oxidation grease prior to installing the replacement antenna. I would also recommend using an antenna with a base spring to you have some additional flexibility in case you hit a low tree branch or something.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] radio antennae [message #280337 is a reply to message #280325] |
Sat, 20 June 2015 08:04 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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Yes, it is a bad idea. The antenna has two components. In the case of a vertical antenna one of the components is the ground plane which is the body to which it is mounted. The GMC mirror is attached to the plastic body and plastic does not make a ground plane. So 1/2 of your antenna is missing. The same goes for CB antennas mounted there but some people still do it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] radio antennae [message #280341 is a reply to message #280284] |
Sat, 20 June 2015 08:11 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Here's one on the Allpar site (excellent site for Mopar freaks):
http://www.allpar.com/stereo/ultimate/index.html
Note 'AM ST" on the selector.
As to an antenna on the mirror mount... I have a CB antenna on mine and it took some finagling to get it to radiate - since I have Ramco mirrors whose arms are composite. While a receiving antenna might work OK there, it will do better on the roof if you can get it there. I'd still extend tin up to the windshield under the inner cap. I had an 18" center loaded CB antenna on an Econoline some while back which worked well. I let it go with the van, I wish I hadn't. Dunno who made it. Ken B?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] radio antennae [message #280344 is a reply to message #280341] |
Sat, 20 June 2015 08:52 |
Mike Kilroy
Messages: 80
Registered: July 2006
Location: Farmersville, OH (near D...
Karma: 0
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----- Original Message -----
From: "Johnny Bridges"
To: gmclist@temp.gmcnet.org
Sent: Saturday, June 20, 2015 9:11:28 AM
Subject: Re: [GMCnet] radio antennae
Here's one on the Allpar site (excellent site for Mopar freaks):
http://www.allpar.com/stereo/ultimate/index.html
Note 'AM ST" on the selector.
As to an antenna on the mirror mount... I have a CB antenna on mine and it took some finagling to get it to radiate - since I have Ramco mirrors whose
arms are composite. While a receiving antenna might work OK there, it will do better on the roof if you can get it there. I'd still extend tin up to
the windshield under the inner cap. I had an 18" center loaded CB antenna on an Econoline some while back which worked well. I let it go with the
van, I wish I hadn't. Dunno who made it. Ken B?
--johnny
--
'76 23' transmode Norris upfit
Braselton, Ga.
"Sometimes I wonder what tomorrow's gonna bring when I think about my dirty life and times" --Warren Zevon
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Mike (AC8V) & Vickie Kilroy
'73 Canyon Land 26' sidebath
455/ceramic filled crossovers
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| Re: [GMCnet] radio antennae [message #280364 is a reply to message #280345] |
Sat, 20 June 2015 14:54 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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My 2 meter Ham Antenna is mounted on my mirror mount and it works very well. However, the antenna that I selected does not require a ground plane to work against.
Considering the quality of CB offerings, I doubt that very sophisticated antennas are available. But, all that shiny stuff looks good, radiates not so much.
Tom, KA4CSG
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] radio antennae [message #280370 is a reply to message #280284] |
Sat, 20 June 2015 15:57 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Actually, there were some excellent CB antennas made, including some center fed balanced ones you could theoretically use in free space. Someone (A S maybe?) even made a matched pair to put on big rig mirrors with a little phasing box so you could point the signal to a surprising degree. Whether anyone still makes decent ones, I dunno. The best vertical radiator for CB is still going to be ~~109" steel whip,which wouldn't be that hard to mount on a GMC, using one of the 4 inch round mounts with a big spring Bolt it on the side of the coach and it won't stick out as far as the mirrors, so you won't wipe it off. (As an aside for the techies, take an admittance bridge and look at a 109 whip - you'll find it a lot closer to 25 Ohms than 50. Tee two equal length pieces of 50 Ohm cable to it and the signal will improve)
If I have to replace my furnace, I'm going to have to patch at least one large hole. I could mount a whip there and save some body work. CB is the only way besides my cell to talk to Galbavy headed to or from a rally.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] radio antennae [message #280417 is a reply to message #280370] |
Sun, 21 June 2015 03:46 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Johnny Bridges wrote on Sat, 20 June 2015 15:57
** SNIP **
CB is the only way besides my cell to talk to Galbavy headed to or from a rally.
--johnny
You could always use a megaphone to talk to Galbavy. They have about the same range as CB and have the added advantage of not needing any power and are highly directional.
TIC
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] radio antennae [message #280419 is a reply to message #280417] |
Sun, 21 June 2015 05:24 |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
Karma: 7
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Ken Burton wrote on Sun, 21 June 2015 03:46Johnny Bridges wrote on Sat, 20 June 2015 15:57
** SNIP **
CB is the only way besides my cell to talk to Galbavy headed to or from a rally.
--johnny
You could always use a megaphone to talk to Galbavy. They have about the same range as CB and have the added advantage of not needing any power and are highly directional.
TIC
Zing.
Heh.
Let me get some popcorn, this could be epic...
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| Re: [GMCnet] radio antennae [message #280425 is a reply to message #280284] |
Sun, 21 June 2015 08:34 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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A decent (assuming someone still manufactures them) CB works about as well as a decent 10 meter rig at the same power. However, the truckers don't do ten, so you won't find out where the po-lice are hiding without the CB. I remember Mr Tom (prexy of the ham club in Tuscaloosa at the time) reminding the members, who were up in arms over losing 11 meters to the 'fools'. He quoted the number of licensed CBs (which was probably half the ones in use at the time) and the number of ham licenses and noted "If they allocate on popularity, we'll get 11 back and CB will get the rest of our bands". That group turned a bunch of civic minded CBers into hams.
--johnny
ex KA4MNW, ex 24Q1719
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] radio antennae [message #280492 is a reply to message #280284] |
Mon, 22 June 2015 13:03 |
bumpersticker
Messages: 60
Registered: February 2004
Location: Redondo Beach, CA
Karma: 0
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Marcel:
Before you trash the oem antenna take a look at the base of the antenna.
The insulator on the base of mine got painted and shorted out the
signal completely. I scraped off the paint and it works like new.
Worked for me!
Bob Cook
78 Birchaven
75 Avion (In work)
Redondo Beach, CA
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| Re: [GMCnet] radio antennae [message #280496 is a reply to message #280492] |
Mon, 22 June 2015 14:37 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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If you must have a CB, get a small one and use it for monitoring the traffic. An antenna used primarily for receiving is much less of a big deal than one for transmitting that "5 watts." A quick reach for the volume control can turn down the trash talk. Would be nice near big cities, but my GPS has traffic alerts. I don't push it hard enough to excite cops.
Just my drift. I would actually rather monitor weather.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] radio antennae [message #280506 is a reply to message #280284] |
Mon, 22 June 2015 15:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Somneplace I got a Radium Shack weather radio with mute, and I think it runs on a 12V wallwart... which means I could stick it in the coach. And I fatfingered the old call, it was KA5MNW, I believe - issued when we were in Tulsa. Ain't that 5 land? I got a cheap (read 'free') GPS so I ast the truckers about traffic. It's a $35 convenience. As I've said, in my game, 1KW is a peanut whistle, not worth getting aroused over.
But to answer the original, put the antenna on the roof and stick a spring on the mount as someone said. Ought to work fine.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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