Radio and hidden antenna installed. Yay! Except not..

[moparedtn]

Pretty sure it isn't supposed to do this.
Yes, everything is wired as factory; colors on wires even matched.

 

[kiwigtx]

Rock-n-Roll.

 

[moparedtn]

I was hoping someone would recognize the sound this thing is making and perhaps tell me what to try to correct it?

 

[Bb70charger500]

Sounds like she's going to blow! I'd check the radio guts for a bad resistor or capacitor maybe or something crossed inside!

 

[Bb70charger500]

I know they sell a rf capacitor or something that you might need if that radio doesn't have one in it kinda like hooking up a old record player to a new stereo you need a pre amp in line same concept but it deal s with radio frequency

 

[kiwigtx]

I was hoping someone would recognize the sound this thing is making and perhaps tell me what to try to correct it?

Showing the front of your radio tells us nothing. Give us the model and brand of the 'hidden antenna' and then you might get some answers flowing.
That noise tells me either your radio is toast, or the antenna is not matched to the frequency band required....or you're shooting 12 volts up the antenna ???

 

[khryslerkid]

Some of these rock bands would pay dearly for that setup!

Definitely a feedback.

 

[moparedtn]

Showing the front of your radio tells us nothing. Give us the model and brand of the 'hidden antenna' and then you might get some answers flowing.
That noise tells me either your radio is toast, or the antenna is not matched to the frequency band required....or you're shooting 12 volts up the antenna ???

Makes the same noise with no antenna connected at all.
Again - wiring is exact as factory.

 

[Billccm]

Motorboating is the technical term. Bad capacitor in your push pull audio.

 

[Billccm]

If you can solder I can help you fix it. PM me with your cell number and I'll call you tomorrow.

 

[Bb70charger500]

I agree with the above statement now that he said motorboating pop the United open let's see what's under her dress!!!

 

[moparedtn]

If you can solder I can help you fix it. PM me with your cell number and I'll call you tomorrow.

Thanks very much, Bill. I knew someone would recognize what the thing is doing.
The gentleman who sold it to me is offering exchange or refund, so I'm going to let him try to make good on the deal, since it was a substantial amount of money involved.
If that goes south, I'll certainly be in touch! Thanks again!

 

[Billccm]

I worked in a TV repair shop in the late 1970s early 1980s (yes there was such a thing as TV repair back in the day). Many, many of these radios came across my bench. Repaired lots of them. New capacitors fixed them most of the time. Occasionally the push pull audio transistors needed replacement with new bias networks.

It seems the tuning wheel is now cracking on these due to age. FBBO members JimKueneman and Threewood have had to re-glue these. For the most part they are reliable, great performing radios.

Good luck with your replacement. Double check grounding on your install, and maybe even add a strap if your is missing, etc.

 

[eldubb440]

 

[moparedtn]

I worked in a TV repair shop in the late 1970s early 1980s (yes there was such a thing as TV repair back in the day). Many, many of these radios came across my bench. Repaired lots of them. New capacitors fixed them most of the time. Occasionally the push pull audio transistors needed replacement with new bias networks.

It seems the tuning wheel is now cracking on these due to age. FBBO members JimKueneman and Threewood have had to re-glue these. For the most part they are reliable, great performing radios.

Good luck with your replacement. Double check grounding on your install, and maybe even add a strap if your is missing, etc.

Thanky kindly.
As far as grounding goes, I figured the mounting hardware (bolts to the instrument panel) would take care of that. No?

 

[Billccm]

Recalling from memory, the 'main ground' for the radio is the rear mounting bracket. I do remember removing many of these radios from cars and a ground strap was from the rear bracket mount to the firewall. Not all cars had these, but some did.

I assume the ground of the front bolts is sufficient, unless there is painted surfaces that would interfere.

Not to get too deep into theory, but these radios have a (excellent designed) Push Pull audio output amplifier. If the radio powers up such that the audio amplifier is slightly out of phase, it will 'motorboat' (oscillations). There is a paper capacitor in the amplifier circuit that opens up and does not keep an AC ground in the amplifier, hence it will oscillate on power up. The fix is a replacement capacitor ('orange drop' type) that is epoxy coated that will last the life of the radio.

 

[moparedtn]

Recalling from memory, the 'main ground' for the radio is the rear mounting bracket. I do remember removing many of these radios from cars and a ground strap was from the rear bracket mount to the firewall. Not all cars had these, but some did.

I assume the ground of the front bolts is sufficient, unless there is painted surfaces that would interfere.

Not to get too deep into theory, but these radios have a (excellent designed) Push Pull audio output amplifier. If the radio powers up such that the audio amplifier is slightly out of phase, it will 'motorboat' (oscillations). There is a paper capacitor in the amplifier circuit that opens up and does not keep an AC ground in the amplifier, hence it will oscillate on power up. The fix is a replacement capacitor ('orange drop' type) that is epoxy coated that will last the life of the radio.

Wow, thanks. You're into the world of Mr. Horman (the gentleman I bought it from) with that explanation; I'm sure he'd understand that stuff.
I just figured if the thing powered up and the internal light came on with the dash lights, I had a good enough ground.
There is a ground strap behind it in the dash I think; it's mangled pretty much and I can't maneuver well enough under there because of my size and surgery war wounds, so I didn't see where or how it was mounted in there, but it certainly got in the way of the antenna lead getting into the radio receptacle hole.
It had a little hook about where it should grab the radio, but being so bent up, it wasn't real close, so obviously someone in the past simply bent it out of the way.
Now that I know it's there, when I take this radio back out, I'll try to get it bent back into place.
Thanks again!