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Re: Tube radio tuning thread slipping
The dial cord may will likely need replacement, good luck finding anyone who can do it. There are some chemicals ("non-slip" from GC) that might be applied to the cord at the dial or at the tuning capacitor, but I would recommend that this be done by a tech.
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you have to have a vtvm a schematic of the radio and a replacement tube if necessary .With these tube types be very careful not to touch anything you shouldn't because you could get a terminal shock. with the schematic check the voltage spec and make sure the tube is actually working properly ,then check the socket to make sure that the correct voltage is getting to it Make sure you don't have any static because it will short out the radio.
vr4 turn it to the left all the way and ask for a radio check.If no one can hear you then turn it all the way to the right and have someone give you a check. You may want to check the SWR to the antenna while your at it. Thats all you can legally do.
Your mic has a series of contacts which cut off the speaker before you transmit and activate the transmitter. If the mic has screws holding it together. With the radio power off. Open the mic and check the spacing between the contacts if it is not enclosed. Some are sealed in a casing. You want to verify that the contacts are not sticking or too close together allowing other functions to stay on.
If you cannot check the contacts. Unplug the mic connector. Get a copy of the mic wire functions and use an Ohm meter to verify that the speaker leads disconnect when the mic button is keyed. It should read "0" when the mic button is pressed. If not, then there is a problem in the mic button switch and you will need a new mic.
Carefully inspect the mic cable for wear breaks. The wires inside are easily damaged when the shielding is damaged. Cables can be repaired. Be sure to slide on two to three shrink tubes to cover the repair job when done. Slide on the tubes and heat them one at a time to create a good protective shield for the wires. This involves several solder connections which will need a small shrink tube on each wire solder. Electrical tape can be used but it will end up a large bulge in the cable afterwords. This should be considered a temporary repair since the strength of the mic cable will be compromised. Stretching the cable afterwords can result in a wire break.
Next check the connector where the mic attaches to the radio, Often there are two small screws which can be removed so you can check the wire connections. A lose wire may be making contact with another contact when the mic is moved around allowing the speaker to stay on during transmit. A small lose strand of wire will account for the noise. After a lot of use the contacts in the plug can become lose if you frequently stretch the cord pulling on the connector. If it is the problem make a note of the wire positions. Then remove the leads with a solder iron. Be careful not to overheat the small metal post as the posts are seated in a plastic mold which can be damaged when overheated. Slip shrink tubing onto the mic cable. If the clamp was not very snug use more than one piece of shrink tubing. Cut off the bare ends and strip back about a 16th (just enough to solder back on). Re-solder the fresh wires to the pins. Over time the wires going into the solder weaken and break. Make sure there are no lose wire strands which could touch another pin. Slide down the shrink tube as far as possible and heat with a match or lighter. Re-attach the clamp so that it holds the cable snugly.
If the problem is not in the mic switch, cable or connections, you will need to take the radio to a technician.
You can also check for mic related problems by using a known good mic. However it should be for the same model radio. Pin numbers and configurations vary between radios, even the same brand of radio. Just because it fits the connector does not mean it will work properly and can even damage the radio.
If you are asking these questions, you should not be tuning anything inside the radio.
Equipment is need to measure these to ensure proper tuning.
you need a watt meter that reads AVG and PEP. A volt meter, and an oscilloscope to align a radio, as well as an alignment guide.
If you are just trying to get more power out of the radio, don't touch anything else in the radio except for VR4. Turn it all the way to the left. Counter clockwise. This will turn the modulation to max.
Playing with anything else with out the proper metering equipment will most likely ruin the radio.
it sounds like the serpentine (fan belt) is slipping and causing your squeal. If you haven't replaced it for a while you could be in need of a new one. When they get old the rubber gets hard and stretches.When you hear the squeal the belt is slipping and the friction from this causes heat and warms the belt and makes it stickier and it will then stop slipping. If your battery is being drained while the car is off or if you need to crank it for an extended period of time the extra strain from the alternator bringing the system back to proper voltage can also cause this as well.But replacing the belt is the first place to start. hope this helps!
What you are looking at is a powdered iron core from one of the tuning coils in your unit. They are used to match circuits together. The brown tube is the one it is out of. The screw is used to match the output of the amplifier to the antenna. All systems are a little different so you need a way to fine tune the system. The closer the circuit is to matching, the more power it will transfer. The fact that the one tube is black and one is brown (and near the antenna output) leads me to conclude that it goes in the brown one. There definitely needs to be one on the antenna output to match it. The black one is probably plastic while the brown one is cardboard or fiber. If that is the case the black one never had a tuning coil because it is a fixed value inductor. How do you know how far to screw it in? If you have an SWR meter (or a friend you can borrow one from) hook it up, do a calibration, put it in the "reflected mode", and while transmitting turn the screw in until the meter drops to it's lowest and begins to rise, then back it out 1/2 a turn. You should see the meter begin at a high level and drop as you turn in the screw. This is because as you get the system impedance closer to a match there is less reflected wave and more signal propagated from the antenna. This should result in improved reception for you and your friends. It would also be a good idea to put a drop of household glue on the screw threads to lock it in place. Don't overdo it though because you may need to retune it in the future if you get a new antenna or change anything in the system. Good luck.