64' Ford Falcon Radio Buzzing

[caphair]

Re: 64' Ford Falcon Radio Buzzing

Couple questions:

1. Why was the C to E reading on the output transistor low but it still works? Is it that the design of that transistor? I'm used to reading infinite ohms from C to E on modern ones

2. Is the IF circuit part of digital radios as well?

If anyone can provide any links as to how exactly radios work it'll be appreciated. Can't seem to find anything with detail of every circuit. This project has got me curious

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

I already pointed out the antenna trimer in post #22. It won't match worth a dam using a piece of wire, but adjust it if you like.

I did not read all the post. Sorry.

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

Couple questions:

1. Why was the C to E reading on the output transistor low but it still works? Is it that the design of that transistor? I'm used to reading infinite ohms from C to E on modern ones

2. Is the IF circuit part of digital radios as well?

If anyone can provide any links as to how exactly radios work it'll be appreciated. Can't seem to find anything with detail of every circuit. This project has got me curious

So I did not know you were using a piece of wire for your antenna. If you have a trim cap on the antenna. You will need to spray it with contact clean then turn if back and forth until it is free moving and let dry before use. . If are using wire you can build your own FM antenna. AM is just a lot of noise. If you want to build a FM antenna. The best thing is clear 300 ohm antenna wire, however you can use insulated wire. You will need to create a loop with 2 wires running side by side up against each other. The length needs to be 30". Being of equal length is critical. The two wires need to be stripped on each end of the 30 inches. Then these wires on each end need to be twisted together. Now measure 15" from one end and cut just one wire in two. This is were you will connect your down wire for your antenna. The down wire will be two wires side by side up against each other of equal length. This length will be how far your antenna is from your radio. Also, were you connect the down wire to the antenna you will either need to rap electrical tape or the two wire need to be secure enough so they do not touch. At the radio end one wire will go into were the antenna plugs in and the other wire will go around the outside of were the antenna plugs in which is chassis ground. These wires at the radio end need to be stripped and should not touch each other. The antenna can be magic tape to the upper back windshield. Or you can go to the auto store and buy an antenna.

[stj]

Re: 64' Ford Falcon Radio Buzzing

i doubt it's an FM radio - there probably wouldnt have been anything to receive when it was made!!

[R_J]

Re: 64' Ford Falcon Radio Buzzing

DO NOT spray the trimer with anything, It works by bringing two plates closer together or or moving them apart, they usually have a mica insulator
The I.F. section is tuned to (auto radios) 262.5khz, (other radios use 455khz) the station broadcasts on a frequency and the car radio has a local osc. that when combined together create a difference frequency of the i.f. frequency, that is passed through the i.f. circuit and amplified.
By using an Intermediate Frequency you can have a narrow band with high amplification without having to cover the whole am band
This reduces interference and gives better selectivity of stations
when you tune to 1300khz the osc. is at 1562khz producing a sum and a difference frequency 1562 + 1300 and 1562 - 1300 . the I.F. takes the lower 262 and amplifies it then sends it through a diode and filter to the audio circuit
when you tune to 540 the osc. is at 802 khz still producing a I.F. frequency of 262 so no re-tuning of the i.f. is required for a different radio station, only the local oscilator needs to be changed.
So You have an antenna that recieves many frequencies, by tuning the R.F. (first stage after the antenna) to a frequency you will recive only that frequency but because tuning ciruits are not very narrow you may pick up more than one station. so you add a Local Oscilator and beat the two frequencies together, When you combine two frequencies they add and subtract producing two other frequencies, in the above example 1562 + 1300 = 2862 (that won't pass through the I.F. so is rejected) and 1562 - 1300 = 262 (that pass through the i.f.) which is a narrow bandwidth around 10khz wide
a station at 1310 next to it 1562 + 1310 = 252 which is outside the I.F. band so you would not pick it up at the same time.
after that the signal is passed through a diode and the high frequency r.f. carrier is removed leaving you with a audio frequency that gets amplified put through a device to control the level (volume control) and off to the power amplifier and speaker.
This may also help https://en.wikipedia.org/wiki/Superheterodyne_receiver

Germanium transistors have lower forward voltage drop of around .27 volts vs silicon which is .7 volts so its possible the transistor was partly turned on showing the lower e - c reading. also Geranium audio power transistors are usually a bit leaky

[redwire]

Re: 64' Ford Falcon Radio Buzzing

What are you powering the radio with? I hope a quiet 12VDC power supply good for an amp or two, grounded. Otherwise hum and buzz - the antenna jack is pain to connect a piece of wire to. If you short the antenna jack, there should be very little buzz/hum, although surely dried out electrolytic capacitors.
I'd leave the tuning caps/coils until last to monkey with.

It is probably similar circuit to a 1963 Bendix i.e in a Ford Falcon: http://falconfaq.dyndns.org/Bendix_3...x_3TBD_01.html

The output stage is class A with output transformer so you will get low C-E ohms in-circuit.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

DO NOT START ADJUSTING ANY OF THE COILS OR OTHER ADJUSTMENTS unless you have the proper alighnment equipment and know how to use it.
These adjustments rarely need to be touched. I've seen what happens when people get into the I.F. cans with there screwdrivers and such, totally fucking them up

These are old radios with poor selectivity, they will pick up noise from anything, even light dimmers, they would pick up noisy ignitions as a car drove by them

[goontron]

Re: 64' Ford Falcon Radio Buzzing

DO NOT START ADJUSTING ANY OF THE COILS OR OTHER ADJUSTMENTS unless you have the proper alighnment equipment and know how to use it.
These adjustments rarely need to be touched. I've seen what happens when people get into the I.F. cans with there screwdrivers and such, totally fucking them up

These are old radios with poor selectivity, they will pick up noise from anything, even light dimmers, they would pick up noisy ignitions as a car drove by them

Sorry to nitpick, You need skill, not equipment. Aligning by ear is incredibly common. A set of ceramic or plastic screwdrivers and a DMM.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

The technicians know what I'm talking about because they have seen the results of aligning by ear or or by eye. But if its your equipment, twist away

[caphair]

Re: 64' Ford Falcon Radio Buzzing

Anyone know why this doesn't use a circuit board? I thought they were used around that time?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

My guess would be the cost of redesign and retooling to change to a pc board and maybe they thought a pc board was not rugged enough for the auto industry. Who knows, the pc boards that came after were not that great either.

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

DO NOT spray the trimer with anything, It works by bringing two plates closer together or or moving them apart, they usually have a mica insulator
The I.F. section is tuned to (auto radios) 262.5khz, (other radios use 455khz) the station broadcasts on a frequency and the car radio has a local osc. that when combined together create a difference frequency of the i.f. frequency, that is passed through the i.f. circuit and amplified.
By using an Intermediate Frequency you can have a narrow band with high amplification without having to cover the whole am band
This reduces interference and gives better selectivity of stations
when you tune to 1300khz the osc. is at 1562khz producing a sum and a difference frequency 1562 + 1300 and 1562 - 1300 . the I.F. takes the lower 262 and amplifies it then sends it through a diode and filter to the audio circuit
when you tune to 540 the osc. is at 802 khz still producing a I.F. frequency of 262 so no re-tuning of the i.f. is required for a different radio station, only the local oscilator needs to be changed.
So You have an antenna that recieves many frequencies, by tuning the R.F. (first stage after the antenna) to a frequency you will recive only that frequency but because tuning ciruits are not very narrow you may pick up more than one station. so you add a Local Oscilator and beat the two frequencies together, When you combine two frequencies they add and subtract producing two other frequencies, in the above example 1562 + 1300 = 2862 (that won't pass through the I.F. so is rejected) and 1562 - 1300 = 262 (that pass through the i.f.) which is a narrow bandwidth around 10khz wide
a station at 1310 next to it 1562 + 1310 = 252 which is outside the I.F. band so you would not pick it up at the same time.
after that the signal is passed through a diode and the high frequency r.f. carrier is removed leaving you with a audio frequency that gets amplified put through a device to control the level (volume control) and off to the power amplifier and speaker.
This may also help https://en.wikipedia.org/wiki/Superheterodyne_receiver

Germanium transistors have lower forward voltage drop of around .27 volts vs silicon which is .7 volts so its possible the transistor was partly turned on showing the lower e - c reading. also Geranium audio power transistors are usually a bit leaky

You are wrong here about spraying with a contact cleaner. These trim caps with a little age can rust causing them to be useless. Contact clearer will make them operational again with out leaving residue.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

I give up!

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

i doubt it's an FM radio - there probably wouldnt have been anything to receive when it was made!!

I am not sure, but at some time around this period they started put AM/FM radios in cars of course it was an option.
Most of the AM antennas are 1/4 wavelength antennas. CBers would use a full wavelength antenna called a whip.

They also had antennas that where power antennas connected to a B+ voltage usually indicated by a blue wire.

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

I give up!

What are you giving up for?

[goontron]

Re: 64' Ford Falcon Radio Buzzing

The technicians know what I'm talking about because they have seen the results of aligning by ear or or by eye. But if its your equipment, twist away

Right, because after refurbishing 100+ tube radios i clearly know nothing.

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

Right, because after refurbishing 100+ tube radios i clearly know nothing.

Your old school which requires a lot of experience. R_J is new school looking for exact precision. You are like timing a car without a timing light. You use your senses. Or how aborigines in Australia track animals by being able to see their tracks on the run. These are different techniques that accomplishes virtually the same thing. Now, if one is inexperienced in either technique the outcome could be bad.

[caphair]

Re: 64' Ford Falcon Radio Buzzing

You've all been very helpful and informative especially RJ with your details about the IF circuit.

Is that still used today in digital?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

You no nothing of my experience and I've been in this industry for probably longer than you've been alive. I am far from NEW SCHOOL as you put it. In the repair business 100 radios is nothing.


and thanks Caphair glad I could help

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

Also, R_J the caps I am talking about use air as a insulator not mica. These caps are exposed to the elements. They are not in the radio. I am unable to find one on the internet. If I do I will post it.