Dear Friends
I have a Philco 89B which only works by connecting antenna cable to a Tube. I have a pic of it.
Question, why is that I have to do this to tune in some radio stations?
Hello Oscar,
We may need help from someone who has worked with an 89B but I believe the antenna connection is the clip on the corner of the chassis. You are connecting the antenna to the cap of the oscillator tube which is the signal input from the 44 rf amplifier tube, thereby bypassing this stage. So, the radio will still tune in stations but won't be as selective. The other clip is a ground connection to be attached to an earth ground.
Not sure exactly what you are asking. Sets built before about 1940 require an external antenna connected to them. After 1940 or so sets had loop antennas which where built into the cabinet and didn't need an external antenna.
If you are asking why your set doesn't work when an antenna to the ant post at the back corner of the chassis. It's likely that the antenna coil inside the set is open and needs a small section rewound. Troubleshooting with an ohm meter will tell the tale.
GL
When I was trying to tune in radio stations, I discovered by accident that touching with my fingers that enhanced the reception and volume.
So, I connected a wire at the tube cap, and that was the way that I could tune in some radio stations
I'm not a radio technician at all, so, I will look for help in checking the antenna coil
Thanks
Ok simple test. Use an ohm meter to measure the resistance from the ANT post to the GND post on the back of the chassis. How many ohms does your meter display?
To radioroslyn
I found .024 ohms in the scale of 2k. Are these 24 ohms?, is this correct?
BTW, I connected a loop antenna to the ANT and GND terminals, and I do have sound, although very little sound volume.
Please give me your comments
P.S. As you may notice, I know nothing on electronic devices, just love them and would like to hear them playing well
Hi Oscar,
Yes that would be 24 ohms. That seems reasonable. Perhaps I jumped the gun I didn't ask which tube do you connect the antenna to for better reception? I assumed it was the rf amplifier tube but maybe it's the mixer. There are about ten different runs of the 89. The major difference is that the earlier runs use a #36 for the mixer and the later a 39/44 tube. Which is yours?? Does your set have a 36 tube in it? Knowing this it will make it easier to follow along. You can pretend your an electron navigating thru all these parts and coming out of the speaker!
>As you may notice, I know nothing on electronic devices, just love them and would like to hear them playing well
So you have a vom. Do you know which end of a soldering iron not to grab?? This job will probably require some soldering skills, doing some voltage / resistance checks, and maybe rewinding a small section of a coil.
Terry
ps 48-482 is no fun to service...