Am Fm radio reception

[scott nutter1]

Does anyone have ideas on how to improve radio reception? I have the stock antenna on top of the cab, and a aftermarket antenna that goes on top of
the windshield. Both work the same(poorly). My FM picks up more than the AM does. My hand held radio will come in crystal clear while my dash radio
will not pick up the station.
Also, the in dash radio has engine rev interference, probably because my plugs may not be resistor type. Should I use the house batteries to power the
in dash radio? Would that stop the engine interference?
Thanks, Scott
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[terry1]

Substitute a known good antenna right to the radio and check the performance. AM is going to require a decent antenna and wire while most modern
radios will get FM with a pocket screwdriver stuck in the antenna socket. If your antenna wire is broken anywhere the signal loss will trigger the AGC
circuit in the radio tuner to turn up the amplifier gain and then all the engine noise that is normally present will now be screaming at you.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[adolph santorine]

Also, try a known good radio.

Dolph Santorine

DE AD0LF

Wheeling, West Virginia

1977 ex-Palm Beach TZE167V100820
Howell EFI/EBL , Reaction Arms, Manny Transmission

>
> Substitute a known good antenna right to the radio and check the performance. AM is going to require a decent antenna and wire while most modern
> radios will get FM with a pocket screwdriver stuck in the antenna socket. If your antenna wire is broken anywhere the signal loss will trigger the AGC
> circuit in the radio tuner to turn up the amplifier gain and then all the engine noise that is normally present will now be screaming at you.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Jim Hupy]

Problem is on the transmit side (usually), rather than the receive side.
5000 watts don't quite cut it in an environment cluttered with transmitter
signals. Back in the days of little to no regulations, 100,000 watt
transmitter power was not uncommon.
And offshore, across the Mexican border "outlaw" radio stations had so
much power that you could hear Mother Maybell Carter picking "Wildwood
Flower" on the barbed wire fences in Texas. But, not today. The FCC has
just about killed off the AM stations. So, its not your radio receiver if
you have no antenna problems. I went to Sirius on my cars, same signal for
thousands of miles. But, on my GMC, I never drive with the radio on. Too
many mechanical sounds of impending doom can be masked by it to suit me.
JWID.
Jim Hupy
Salem, Oregon

On Fri, Nov 20, 2020, 8:10 AM Terry via Gmclist
wrote:

> Substitute a known good antenna right to the radio and check the
> performance. AM is going to require a decent antenna and wire while most
> modern
> radios will get FM with a pocket screwdriver stuck in the antenna socket.
> If your antenna wire is broken anywhere the signal loss will trigger the AGC
> circuit in the radio tuner to turn up the amplifier gain and then all the
> engine noise that is normally present will now be screaming at you.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[scott nutter1]

I forgot to mention that it is a newer alpine stereo in the dash.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[Larry Davick]

My reception was very poor only to find that the connection in the ceiling of the cockpit was loose and almost disconnected. Once plugged in the reception was perfect.

Of course I didn’t find it until I was working on the ceiling!

Larry Davick
A Mystery Machine
1976 Palm Beach
Fremont, Ca.

>
> I forgot to mention that it is a newer alpine stereo in the dash.
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[RF_Burns]

Many auto radios have a "trimmer" capacitor to match the antenna to the AM tuner. The standard auto antenna is 1/4 wave at mid-band of the FM band,
but it is far off of an optimum AM antenna. Check your radio manual for the AM tuner adjustment if it exists.

Back in the day when I worked on this stuff, you set the radio to a weak station around 1400Khz, then tuned the trimmer for best reception.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[Matt Colie]

> Many auto radios have a "trimmer" capacitor to match the antenna to the AM tuner. The standard auto antenna is 1/4 wave at mid-band of the FM
> band, but it is far off of an optimum AM antenna. Check your radio manual for the AM tuner adjustment if it exists.
>
> Back in the day when I worked on this stuff, you set the radio to a weak station around 1400Khz, then tuned the trimmer for best reception.

Wow Bruce,

You must be almost as old as I am. Did some also contain "fire bottles"?? Did you ever run into those weird types with 12V B+ so they did need a
vibrator power supply? Those did last long. Those, nuvistors and compactrons are all gone now.

Matt

--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

 

[Ken H.]

Hmpfff! "...almost as old as I am..." and then talk about 12 volts,
nuvistors, etc. Don't you remember the 6 VDC vibrators supplying ALL octal
vacuum tubes, like I do?

Not to mention the scars I still bear from having a pot of molten tar
kicked over on me while watching the making radio batteries from dry cells
during WWII. Luckily, my great uncle, Dr. Marion Folsom, drove up in his
Model T about then.

I still remember the tales told about my uncle who, when I was a little
boy, had one of the first 2-way radios in his Georgia (no "GA" foolishness
in those days) Highway Patrol cruiser. He was widely known for one of his
first broadcasts on it: The announcement that anyone coming to Newton (low
on the bank of the Flint river) that day "would have to do so by boat."

Let's see now, how can I tie this to the GMC???

Ken H.

On Fri, Nov 20, 2020 at 9:18 PM Matt Colie via Gmclist <

> > Many auto radios have a "trimmer" capacitor to match the antenna to the
> AM tuner. The standard auto antenna is 1/4 wave at mid-band of the FM
> > band, but it is far off of an optimum AM antenna. Check your radio
> manual for the AM tuner adjustment if it exists.
> >
> > Back in the day when I worked on this stuff, you set the radio to a weak
> station around 1400Khz, then tuned the trimmer for best reception.
>
> Wow Bruce,
>
> You must be almost as old as I am. Did some also contain "fire
> bottles"?? Did you ever run into those weird types with 12V B+ so they
> did need a
> vibrator power supply? Those did last long. Those, nuvistors and
> compactrons are all gone now.
>
> Matt
>
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Jim Hupy]

I have some less than fond memories of 6 volt batteries, charged with
generators instead of alternators, and vibratory power supplies that ran
those batteries down in short order when I was parked in some secluded spot
with an "interesting person of the opposite sex". Before cellular
telephones, and nearest houses miles away.
Makes me appreciate the luxury of GMC motorhomes and all the
convenient stuff like generators and isolated starting batteries.
Some of that stuff of the past was just adequate.
Jim Hupy
Salem, Oregon

On Fri, Nov 20, 2020, 8:43 PM Ken Henderson via Gmclist <

> Hmpfff! "...almost as old as I am..." and then talk about 12 volts,
> nuvistors, etc. Don't you remember the 6 VDC vibrators supplying ALL octal
> vacuum tubes, like I do?
>
> Not to mention the scars I still bear from having a pot of molten tar
> kicked over on me while watching the making radio batteries from dry cells
> during WWII. Luckily, my great uncle, Dr. Marion Folsom, drove up in his
> Model T about then.
>
> I still remember the tales told about my uncle who, when I was a little
> boy, had one of the first 2-way radios in his Georgia (no "GA" foolishness
> in those days) Highway Patrol cruiser. He was widely known for one of his
> first broadcasts on it: The announcement that anyone coming to Newton (low
> on the bank of the Flint river) that day "would have to do so by boat."
>
> Let's see now, how can I tie this to the GMC???
>
> Ken H.
>
>
> On Fri, Nov 20, 2020 at 9:18 PM Matt Colie via Gmclist <

>

> > > Many auto radios have a "trimmer" capacitor to match the antenna to the
> > AM tuner. The standard auto antenna is 1/4 wave at mid-band of the FM
> > > band, but it is far off of an optimum AM antenna. Check your radio
> > manual for the AM tuner adjustment if it exists.
> > >
> > > Back in the day when I worked on this stuff, you set the radio to a
> weak
> > station around 1400Khz, then tuned the trimmer for best reception.
> >
> > Wow Bruce,
> >
> > You must be almost as old as I am. Did some also contain "fire
> > bottles"?? Did you ever run into those weird types with 12V B+ so they
> > did need a
> > vibrator power supply? Those did last long. Those, nuvistors and
> > compactrons are all gone now.
> >
> > Matt
> >
> > --
> > Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> > GMCES
> > Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> > Brakes with Applied Control Arms
> > SE Michigan - Near DTW - Twixt A2 and Detroit
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Ken B]

Let's start with the basics on vehicle AM radio antennas. They require a good ground at the base of the antenna. The car / vehicle body is 1/2 of
the antenna system and it's connection to the coax to feed RF to the radio is at the base of the antenna. NOT AT THE DASH OR RADIO

Almost every AM radio reception complaint I have ever worked on has been a poor ground connection where the antenna is mounted. On a car it is
usually a rusty fender. You disassemble the antenna mounting and simply clean the fender or wherever it is mounted until shiny. Occasionally it was
simply loose and only needed tightening. The GMC roof mount is the same thing except it is mounted in Aluminum which corrodes rather than rusts.
Coat all of those loosened pieces with anti-seize when reassembling.

The other thing you can do to check this is to unplug the antenna from the radio and check the resistance between the center conductor of the cable
and the antenna shaft on the roof. It should be around 1 or 2 ohms. Then check the shield of the cable too a good body ground. It too should be
less than 3 ohms. DO NOT USE THE DASH or anything mounted to it as a ground connection for your meter when metering this. The dash is electrically
connected to the engine ground and not the body ground.

I had mine corroded and had to clean it up about 15 years ago.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[RF_Burns]

You guys are funny!... Unfortunately I am old enough to have worked on some Motorola Twin V radios in Taxi service. A couple of those had
motor-generator sets instead of vibrators for the high voltage tubes. Another customer had some nice Marconi units that to save power the transmitter
tubes were cold until you hit the PTT then they instantly (about 2-3 seconds) heated up by drawing about 30 Amps of heater current.

GE Prog Line (Progress Line) low-banders were fun too.

I was still fixing Motorola Business Dispatchers and Pye radios into the '90s. They had transistor receivers and tube transmitters.

Yes Matt I worked with all those steam tubes in my day.

On the farm my father would rather crank start tractors than fix the generators. He was running them on 12V rather than 6 by just switching them out
of the car (our battery charger) as we had no electricity on the farm. When the generator on the Ford 8N went south, swapping batteries just was a
pain. So I replaced the generator with a nice Delco alternator. It started much better on 12V (Grin). Swapped the lights to 12V and it was the only
tractor with a working electrical system.

Back to radios (which none of my dads vehicles had until into the '70s). (GMC content here)... I always loved the soft clunk sound of a GM radio
turning ON. The heat off the class A audio amplifier was also nice in the winter.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[scott nutter1]

Ken Burton,
Would it be a good idea to pull a ground wire from the radio chassis to a good ground source? Would that improve my AM reception?
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas

 

[johnny]

Ground it well, and be sure the antenna is working well. And realize, the AM section of current receivers is shiteye. Some of the Alpines are OK for
AM, some aren't. As Bruce said there's likely an AM antenna trimmer on it someplace, look in the Alpine book and set it as advertised.

J.O. Weldon and Nestor Questor built most of the Mexican high power transmitters un der the Continental Electronics banner. I had the privilege of
sitting at the table at a convention with several Gurus of the industry (Sellmeyer, Silliman pere and fils, Orban, Foti, Clark and several others) in
the Continental hospitality suite drinking Mr J.O.'s whiskey and listening to his stories of the Mexican transmitters for several hours while Nestopr
tended bar. (Nestor's idea opf bartending was, if he gave you a full glass of whiskey, he wouldn't have top serve you again quite as soon) Here's a
short blurb: https://contelec.com/history/

--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

 

[Ken B]

Do NOT install a wire between the radio and body ground. The radio is already attached to engine ground and if you add the suggested wire you are
making a ground loop. (A noise receiving antenna at some undetermined frequency located a few feet away for the two biggest noise generators in the
the coach. {the ignition system and the heater fan.})

Also if that wire were installed and one of the braided frame to engine or frame to body jumpers were to open up, which happens frequently on these
coaches, you now have an alternate ground path for all of the charging current going to the house batteries and to other things. That wire will not
be able to carry the current. It will burn under those conditions.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[RF_Burns]

Ken,
The 77-78 chassis wiring diagram I have shows the radio ground as being through the radio chassis, not a separate wire, so it gets ground from the
dash frame it is mounted to. It also shows the dash is grounded by a separate wire direct the battery Neg (-), NOT to the engine block.

Since the antenna shield is grounded at the antenna (on the body) and also at the radio, the radio chassis is connected to the body ground. Therefore
as-built there is already a ground loop in place.

If the engine to body ground straps fail, the antenna cable shield will carry the current. If the battery to engine block ground wire fails, again
the antenna coax will complete the ground.

My Farm-boy mechanic and 45+ years in mobile radio communications tells me that separate dash ground wire from the battery should be disconnected from
the battery and grounded at the engine.

When GE came out with their first microprocessor controlled, programmable radio we were having endless troubles with instability of the transmitter
frequency. They finally sent an Engineer out to look at a new Police car with this issue. He promptly told me I had connected the radio power wrong,
the ground wire had to go directly to the battery. I disagreed arguing the radio ground had to share the same ground as the radio case (mounting
point) and the antenna ground, therefore be grounded to the vehicle body. But he insisted so we wired the radio ground wire to the battery. It did
not fix the radio's instability, but as soon as the engine was started some starter current flowed though the new radio ground wire from the battery
and out the case of the radio onto the body ground, through a grounding wire from the body to the engine block. This current was enough to burn a PCB
trace from the radio ground wire connection to the radio chassis (case). This caused the 5 volt regulator to loose its proper ground reference and
smoked the radio's microprocessor. The Police Chief was not amused and the Engineer was dumbfounded.

GE never did fix the issue as they claimed it worked fine on the bench (into a dummy antenna load) Trouble was when connected to an antenna the RF
field when transmitting would upset the radio's voltage regulator powering the Voltage Controlled oscillator (VCO) causing stability in the VCO and
therefore transmitter frequency. Once again... works as designed, but not designed to work!

Just my experience
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[johnny]

You got to figure anyone who couldn't spell 'master' probably couldn't design a stable radio

(Actually they spelled it 'Mastr' so they could copyright it)

--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

 

[RF_Burns]

GE claims Mastr stands for "Mobile and station transistor radio".

But I agree, my experience has been GE couldn't seem to make anything that worked with any reliability. Always gave me a warm and fuzzy feeling when
getting on a plane to see the GE logo on the engines!
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[d c *mac* macdonald]

GE's Mastr 2-way radios were excellent performers.
I have used and maintained lots of them.

D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com

________________________________
From: Gmclist on behalf of Johnny Bridges via Gmclist
Sent: Wednesday, November 25, 2020 07:26
To: gmclist
Cc: Johnny Bridges
Subject: Re: [GMCnet] Am Fm radio reception

You got to figure anyone who couldn't spell 'master' probably couldn't design a stable radio

(Actually they spelled it 'Mastr' so they could copyright it)

--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

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Ken B]

> Ken,
> The 77-78 chassis wiring diagram I have shows the radio ground as being through the radio chassis, not a separate wire, so it gets ground from the
> dash frame it is mounted to. It also shows the dash is grounded by a separate wire direct the battery Neg (-), NOT to the engine block.
>
> You failed to follow that wire any farther at the battery. That wire continues on through the battery connector and to a bolt on the engine Block
> (engine ground). We frequently call that continuation cable the negative battery cable.
>
>
> Since the antenna shield is grounded at the antenna (on the body) and also at the radio, the radio chassis is connected to the body ground.
> Therefore as-built there is already a ground loop in place.
>
> While the above is partially true, the antenna connector shield side is NOT DC connected to the radio frame itself. SO there is NO connection
> between body and engine ground there
>
> If the engine to body ground straps fail, the antenna cable shield will carry the current. If the battery to engine block ground wire fails,
> again the antenna coax will complete the ground.
>
> That connection inside the radio does not exist. If it did we would have many, many reports of smoked antenna coax cables and blown radios when
> the braided jumpers fail or were forgotten to be replaced on engine and transmission swaps. The engine to frame crossover is located on the back of
> the trans near the rear mount. I have replaced a few of them on other people's coaches.
>
> My Farm-boy mechanic and 45+ years in mobile radio communications tells me that separate dash ground wire from the battery should be disconnected
> from the battery and grounded at the engine.
>
> Agreed, but see previous comment. GM figured why not do it their way and it has worked just fine (other than corroded or loose connections) for a
> long time. The dash is still hooked to engine ground just by a slightly longer route on a 2 or 4 ga. cable.
>
> When GE came out with their first microprocessor controlled, programmable radio we were having endless troubles with instability of the
> transmitter frequency. They finally sent an Engineer out to look at a new Police car with this issue. He promptly told me I had connected the radio
> power wrong, the ground wire had to go directly to the battery. I disagreed arguing the radio ground had to share the same ground as the radio case
> (mounting point) and the antenna ground, therefore be grounded to the vehicle body. But he insisted so we wired the radio ground wire to the
> battery. It did not fix the radio's instability, but as soon as the engine was started some starter current flowed though the new radio ground wire
> from the battery and out the case of the radio onto the body ground, through a grounding wire from the body to the engine block. This current was
> enough to burn a PCB trace from the radio ground wire connection to the radio chassis (case). This caused the 5 volt regulator to loose its proper
> ground reference and smoked the radio's microprocessor. The Police Chief was not amused and the Engineer was dumbfounded.
>
> GE never did fix the issue as they claimed it worked fine on the bench (into a dummy antenna load) Trouble was when connected to an antenna the
> RF field when transmitting would upset the radio's voltage regulator powering the Voltage Controlled oscillator (VCO) causing stability in the VCO
> and therefore transmitter frequency. Once again... works as designed, but not designed to work!
>
> Just my experience

Improper grounding will bite you frequently and people do not stop to consider it. What makes ours worse is we have 3 separate grounding systems in a
GMC and most people do not stop to consider them.

I did a demonstration one time for Dan Gregg. He attached a ground wire to the base of his Paterson Distributor and ran it to battery negative. I
told him not to do it but he disagreed.

The demonstration was to disconnect the starting battery negative cable from the engine block. Upon attempting to start the engine he promptly smoked
the 12 ga. wire between the distributor base and the battery he had just installed. We replaced the wire and ran it to the engine instead of the
battery.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana