The PHILCO Phorum

http://www.flickr.com/photos/audin/2399654349/



Last night I finished up the capacitor and (some) resistor replacements. I don't have a variac so I quickly built a dim-bulb tester from some random parts i had laying around. Unfortunately the smallest lightbulb i could find was 60w...

So I very carefully applied power to the radio with no tubes inserted. Thankfully nothing went 'poof' and I was rewarded by a faintly glowing tuning dial! So at least that meant the B voltage winding on the transformer was working. The 60w bulb did not light at all (and i chose a non-frosted 60w bulb so i could see lower light levels).

So then I inserted the Type 80 rectifier tube. Again hesitantly flipped the power switch on the tester (i was still unsure about how the chassis -> AC situation was...so i didn't really want to grab the bare radio power switch shaft). This time the 60w bulb glowed dimly and i heard a slight 'tink' sound from the 80. Slowly the filaments in it started to glow. I cycled the power slowly a few more times and each time heard the 'tink'.

Everything I've read basically implies that without a variac this is about as careful as I can be with the first startup (well, a 25w bulb would have been better, but i didn't have one). And the bulb seemed to be reacting just as it should.

For a few moments I pondered poking my meter around to measure voltages but i decided against it.

I turned it off and inserted all the tubes. Again applied power. Thist time the 60w bulb lit brightly. I was a little worried but the radio is supposed to draw 100 watts or something so i decided it made sense. All the tubes glowed. I had previously checked the continuity of the filaments so that wasn't a big surprise. However there was no audio.

I turned it back off and looked at things again. Looked at the bottom to see if anything was getting overly hot. Everything looked good. So i turned it back on. Played with the knobs a bit. Still nothing. But it didn't seem to be burning anything up so I left it on for a minute or two. Then slowly i started to hear sound. It was faint but there was a voice there. Played with the knobs a bit more and you could actually listen to the channel!

I decided to try the 100w bulb. This time there was a squeal as i flipped the power switch. It quickly died down and then there was a period of silence followed by the station again!

So then I went for broke and plugged it straight into the wall. Again some squealing but it works!

At this point I played with it for about 30 minutes. The tuning was very fiddly. You had to work pretty hard to get it in the middle of a station, otherwise you just ended up with distortion from a sideband. Also there was a constant high pitched squeal.

After that i decided to try again with the distance switch in 'normal' instead of 'max'. it was in max when i bought it so i just left it there.

Fired it back up again and...LOUD. Quickly turned down volume. In the normal setting the tuning is much easier. Also the squeal is gone. Is this normal? The volume control is also very scratchy. I have to pull it out again and clean it now that i have some idea of what to do.

Anyway i am impressed and pleased it works!

Hello Audin, Congrats on getting your radio working! You didnt mention in your previous post if you had a longwire antenna attached after initial powerup of the chassis? These old sets need about a 20'-25' pc of wire attached to the ant terminal for good reception in most cases. Enjoy your Philco!

Initially I didn't have an antenna. On the third or fourth attempt I hooked up the old power cord wire as a quick one. I live in Seattle, so there are a lot of strong signals around. I have not hooked up the ground wire. I'm wondering if I should just add a three prong cord for that part...

Now THAT is a neat picture!

When your radio began working (but with squeals), did you have the large tube shield in place that goes over the tubes lined up along the back of the chassis? If not...then, not having the tube shield in place will cause squealing.

Hi Audin, I used to bring my radios up slowly before I got a variac, using a string of the old style christmas lights (the ones with the C7 bulbs). With the string conected in series with the radio just as you would with your dim bulb tester. Start with all the bulbs loose then begin tightening them one at a time. You may want to replace a couple of the bulbs with 25 watt ones to make things go a little faster. Works like a champ!

Steve

Ah, very good. Indeed the tuning squeals go away when the shield is in place. Unfortunately with it in place there is a slight 60hz hum. I wonder where that is coming from. Should it be completely hum free? or should i expect some?

WOW! Nice pic!