The PHILCO Phorum
41-608 no radio stations - Printable Version

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RE: 41-608 no radio stations - Radioroslyn - 12-15-2019

Actually something a little more simplistic would be to remove the XXL tube wrap some wire around the glass part like 3turns. Hook the the unsheilded lead from your generator to one end of the wire you just wrapped around the tube. The other end of the wire around the tube just leave loose (unconnected). Reinstall the XXL tube connect the other lead from the generator to the chassis. With this setup with all is working you should be able tune the generator to the frequency on the radio's dial. Can't align the trimmer for the rf stages with this setup.

If you are not to receive any stations check your voltages @ the XXL tube and the 7B5 tube.

RE: 41-608 no radio stations - 462ron - 12-16-2019

Hi Derek, in post #10 you state that you did finally get a signal through and aligned the IF strip but still no stations received. You should check and see if your oscillator is working. You can "listen" for it  on a working radio by first tuning your Philco to 1000KC and tune a second working radio to 1455KC. Tune the Philco up and down a bit and you should hear a reaction in the second set if it is close by. If not, possibly your oscillator isn't working!

Ron

RE: 41-608 no radio stations - Derek38 - 12-16-2019

This question may sound silly. How do you check the voltage at a tube? Plate, screen and bias

RE: 41-608 no radio stations - klondike98 - 12-17-2019

One way is to use a socket adapter that provides some contacts on the topside of the chassis for you to connect your voltmeter leads to.  Sometimes these show up on ebay. This image was cut from a page on the RadiolaGuy.com page who also may have some available for sale.

[Image: https://www.dropbox.com/s/vg5i66avthljpjw/socket%20adapter.jpg?raw=1]

The other is to turn the chassis on its side so you can get at the bottom of the tube sockets to connect the voltmeter lead to the proper pin.  Of course this involves accessing the chassis while its powered up so you need to be extremely careful.  I usually make the voltmeter connections first then power the set up.

RE: 41-608 no radio stations - Derek38 - 12-17-2019

What voltages should I see

RE: 41-608 no radio stations - Derek38 - 12-17-2019

I am getting only. 5 or so volts

RE: 41-608 no radio stations - Derek38 - 12-18-2019

Well I checked the wires coming from the transformer and found 2 that were loose. I resoldered the connections and now I one very faint station on the low end of the dial! Lots of static.

RE: 41-608 no radio stations - Derek38 - 12-18-2019

Where to go from here

RE: 41-608 no radio stations - Radioroslyn - 12-18-2019

Let's start here  http://jollinger.com/radio/tubes/tube_basing.html
Study the octal/loctal base note the pin location vs the key. This is how you count the pins on these tubes. What we are looking for is voltage on pin 3 of the XXL. Should see some hv there. On the 7B5 we are looking for hv on pins 2 and 3. Pin 6 we should see some - voltage, a few volts.

RE: 41-608 no radio stations - Derek38 - 12-19-2019

Ok if read these right there is no pin on number 3 for the xxl. On the 7b5 pin 2 -1.48 and on pin 3 there is 27.8 and on pin 6 there is -23

RE: 41-608 no radio stations - Radioroslyn - 12-19-2019

Sorry on the XXL I should have said pin 2.
On the 7B5 pin 2 is low should be abt 27vdc. I'd have a look at #18 choke should read abt 20 ohms. If it's open or close to it that could cause the voltage drop from 27 down to 1.4v.
The voltage on the control grid is kinda high too I'd look at #13. If it's gone high it resistance that could be the cause.

RE: 41-608 no radio stations - Derek38 - 12-19-2019

Voltage on pin 2 of xxl is148.7 and as far as the choke there are 27.8 volts before it goes through to the pin where it drops off to 1.16. I will check resistor 13 later.

RE: 41-608 no radio stations - Derek38 - 12-19-2019

What watt are the resisters in this radio

RE: 41-608 no radio stations - Radioroslyn - 12-19-2019

>as far as the choke there are 27.8 volts before it goes through to the pin where it drops off to 1.16
Turn the set off and measure the resistance across the choke.

RE: 41-608 no radio stations - Derek38 - 12-19-2019

There is no reading through the choke