Philco 48-461 radio restoration

Anything related to video and my tools that is not a support request.
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Rocky
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Philco 48-461 radio restoration

Post by Rocky »

Don't worry Sherman. Glue is the right idea but you just used too much. More is not always better. Also, see the cabinet opening for the speaker? There should be no glue applied to the cloth area within that opening, just at the edges. No, nothing on the center rib either. When the new grille cloths come in I'll show you how to do it. As the glue dries you are continuously adjusting the cloth to keep it taut. You'll see.
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Curly
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Philco 48-461 radio restoration

Post by Curly »

Sherman wrote:
Mon Mar 14, 2022 11:28 am
Maybe I need some help.
Quite an admission from the Sherm.
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DG
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Philco 48-461 radio restoration

Post by DG »

Often, initial failure is a prerequisite for success. Remember Edison and the light bulb? Sherman is a hero.

We could ruin 100 cloths and it's still pocket change.
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Bullwinkle
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Philco 48-461 radio restoration

Post by Bullwinkle »

Easy for you to say.
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Rocky
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Philco 48-461 radio restoration

Post by Rocky »

OK Sherman, listen up. No wonder you failed with the grille cloths. The backer board is literally disintegrating in your hands. It is no longer stiff and can't hold the cloth properly. So I made a new one out of masonite, a drill, and a scroll jigsaw. When the new cloths arrive I'll show you how to glue down the cloth. You are on the right track trying to mark the opening for your next attempt, but the horse has already bolted. Throw that thing in the trash. We will attach the new backer with small screws rather than staples. Good for another lifetime.

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Rocky
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Philco 48-461 radio restoration

Post by Rocky »

Here is the fully restored radio 1. Looks pretty good to me. I reckon that painted look around the openings is ugly and this way looks much better. Still waiting for grille cloths for radio 2. While waiting I'll look into saving a log on each indexing operation for DGIndexNV.

BTW, there is one downside to the led dial mod. Because the voltage is derived from the B+ the led doesn't turn on until the B+ comes up, which is about 30-40 seconds from a cold start, at which time the audio also starts up. Once it turns on, however, it is very pretty and effective.

BTW2, I'm experimenting with oscillators to drive an AM transmitter. Gonna use a Wien bridge oscillator stabilized by a small lamp bulb. That circuit was Hewlett's initial claim to fame (y'all heard of Hewlett-Packard, I'm sure).

:salute: Sherman for the finishing and other things.

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Curly
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Philco 48-461 radio restoration

Post by Curly »

Started to say something important but then I ran out of energy.
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Britney
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Philco 48-461 radio restoration

Post by Britney »

I know, right?! I heard that energy is in short supply right now.
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Sherman
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Philco 48-461 radio restoration

Post by Sherman »

No problem with energy here!

Guys, I made a little change to the cabinets. I had noticed with radio 1 that after being assembled there was a hot spot (more a warm spot than a hot spot to be precise) on the top of the radio right above the audio output tube/line drop resistor area. So I put some metal tape on the inside of the cabinet above that area. This reflected and diffused the heat energy such that the hot spot was barely noticeable. Call it a poor man's fan. You may bow down now. :P

Don't sweat the led not coming up until the B+ appears. Even with a normal 47 bulb, it is very dim until the B+ comes up, at which point it goes to normal brightness. Remember, part of the bulb current is B+ current flowing through the rectifier.
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Rocky
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Philco 48-461 radio restoration

Post by Rocky »

Great stuff, Sherm. You sure do think outside the box.

No problems with energy here either. Whee!
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new_guy
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Philco 48-461 radio restoration

Post by new_guy »

Hey, why'd y'all delete my video link?
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admin
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Philco 48-461 radio restoration

Post by admin »

Think PG-13.
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new_guy
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Philco 48-461 radio restoration

Post by new_guy »

Got it. Speaking of reflections.

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Sherman
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Philco 48-461 radio restoration

Post by Sherman »

Guys, you're not going to believe this, but my brilliance has struck again!

Remember earlier I said that the radio 2 chassis sounded better than the radio 1 chassis? With some help from my favorite forum, oops I mean my second favorite forum, I found out why. First, here's the awesome forum:

https://antiqueradios.com/forums/index.php

They helped me to focus on the speaker. Guys, when I had the radio 1 chassis out I inspected the speaker closely and I found grit and a big solder ball stuck between the cone and the speaker frame, both around the outside and around the voice coil. I removed all that cr*p and, you guessed it, the shhhh'ing went away and the radios became indistinguishable.

That is all. You may bow down now.
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Britney
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Philco 48-461 radio restoration

Post by Britney »

:bow:
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Sherman
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Philco 48-461 radio restoration

Post by Sherman »

Thanks Brit! Just curious though. What is "big dick energy"?
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Britney
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Philco 48-461 radio restoration

Post by Britney »

I wouldn't know. Try searching.
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Boris
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Philco 48-461 radio restoration

Post by Boris »

OMG, Sherman signed up on January 6th!
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Baltasar
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Philco 48-461 radio restoration

Post by Baltasar »

Beautiful Florence Ballard, eternal joy for the heart, innocent child of the divine.
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Sherman
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Philco 48-461 radio restoration

Post by Sherman »

Sorry guys, I know you missed me.

Measured > 5Vdc p-p 60Hz ripple on the output tube plate (on radio 2 chassis, which is out for speaker cloth installation). That hum is detectable at the speaker with a differential probe on the 2465B. We gotta shoot for 0Vdc ripple at the speaker. Duh. So guys, I put 100uF at all three caps of the B+ filter. I put an extra 47 ohm resistor between the rectifier and the first filter capacitor. The rectifier tube spec gave 40uF as the specified value. I have bumped that to 100uF with the justification that the added resistor limits turn-on surges. Mr Carlson also recommends this.

After these changes, plate ripple is less than 500mVdc p-p, and there is no measurable 60Hz hum at the speaker. B+ voltages are a little higher with the bigger caps. What do you think of that!?

The cloths are in and Rocky says if I'm a good boy he'll show me how to install them tomorrow. I already ruined two cloths but it wasn't completely my fault, just in case you didn't know.
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Natasha
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Philco 48-461 radio restoration

Post by Natasha »

:shock: Shocking! :shock:
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Boris
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Philco 48-461 radio restoration

Post by Boris »

Dancing on pin's head.
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Sherman
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Philco 48-461 radio restoration

Post by Sherman »

Bullwinkle said that before the changes mooses could hear the hum but people couldn't. Sounds in the forest, I'm not sure. After the changes Bullwinkle says that mooses couldn't hear it anymore, except that he has super sensitive senses and he can still hear the hum a little bit. Sounds reasonable. And the added capacitance reduces noise from the line.

YMBDN --> You may bow down now. :bow:
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Rocky
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Philco 48-461 radio restoration

Post by Rocky »

Great stuff, Sherm. Our big line dropping resistor also limits turn-on surges. Tubes warm up slowly. All those warnings about increasing the capacitance of the first filter capacitor are way overblown and hysterical. The increase in B+ is a volt or two. Insignificant.

What's next? I have the changes for THD demuxing for DGIndexNV ready to go.
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Philco 48-461 radio restoration

Post by Guest »

Sherman wrote:
Wed Mar 30, 2022 10:55 pm
[YMBDN --> You may bow down now. :bow:
Getting a little too big for your britches
The fall from the ladder is fast
:evil:
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