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Topic: Philco 46-1226 Radio (Read 2555 times) previous topic - next topic

Philco 46-1226 Radio

before and after shots  of the Philco 46-1226 code 125

recap and re-resistor and Re-can of filter cap sections and Re-work power transformer and Re-align the IF amps, and add a polarized power cord, add a fuse block, update the 7AF7 section, calibrate an old update error on resistor R102 which was undersized to allow for a PM speaker, troubleshoot and find and repair carbon flash on a Loktal, almost successful at repair of the primary on the audio output transformer but ended up having to use an equal alternative, color coded transformer leads to match the schematic with heat shrink tubing.

I used old school brown drops to keep some degree of antiquity integrated into the outcome,, making the appearance of the renovation to appear as though it may have happened in the 70's.

there are actually people out there taking the old caps out, melting the wax out, pulling out the guts, inserting a modern cap into the cardboard tube, then re-melting the wax back onto the old cap tube then re installing.... thats really respectable when you think about it.  there are even people rebuilding dog bone resistors !!

Radio going back into its cabinet after being down since 1981.  I rigged it up to work "for a while in 97' but it soon broke again.

all is well in the 9.3 to 15.5 MC land.

six weeks of restoration,, didnt bother with looks or a whole lot of cleaning so to speak,, didnt want it to look too good ,, LOL.

With my other improvements and adding a vent mod to the power transformer, I think its good for another half century or more.
I used an old Navy trick to the job but went a step further.  If you want an piece of electronics to "speak" to you later when it breaks, then add a dab of white paint on each part dead center.  When the part fails the color of the paint will physically turn brown.  this give you a visual inspection aid later.
I went a few steps further and designated all the small & large parts with their schematic name.  This will benefit me or perhaps my son's later on.

now i am at 80ma of current draw & 290v on pin 3 of my two 6k6's and 250v on pin 4 of the 6k6's,, in line with code 125 which states the PM speaker power supply update will yield approx 20v more than code 122.  All of this hard work to finally put to bed the old incorrect prints saying my R102 needed to be 300 ohms.  600 ohms at 50 watts is the right solution.  this resistor is now on top with the tubes standing straight up with a heat sync i made up to wick heat to the chassis.

Tom,
that email you sent me in 03' with schematic actually turned out to be several runs prior to this code 125.
In order to make a repair to a 46-1226 code 125, you must use code 122 + run 1 + run 2 + run 3 updates which then = code 125.
there is *NO* known schematic available for this exact code 125.,, it never was printed.
Chuck at the philco workbench was very helpful.

Philco 46-1226 Radio

Reply #1 –
here are the after pics

Philco 46-1226 Radio

Reply #2 –
my first go at hand making a dial needle, didnt take long but since i wanted it fast, i had to make it in two parts.

I was able to leverage about 20 more deg F off that big stand up resistor now getting it down to a reasonable 190deg.  the pig tail copper thing is how i got the temp a tad lower.

i have one tube that glows a tad blue from being gasy,, its not in the anode or cathode or screen so i guess its ok.  it kinda wave around in sync with the music

Philco 46-1226 Radio

Reply #3 –
here is the needle

Philco 46-1226 Radio

Reply #4 –
made up a heat sync for my first three tubes, one that reaches 350degF and tow that reach about 280degF.  Old patents i saw shows ideas about solving this issue so that gave me the go ahead to fab something up with s i have.

the purpose of heat syncs was to lower the temp on one of my tubes that was gasing, causing a cobolt blueish neon look.  apparently harmless in my case because the blue is not in the annode, cathode or screen, its on the glass.  when tunes are playing this blue fog dances with the music,,,, kinda neat actually.

now its back in service.  Next to solve a random wire antenna to get outside the bubble of the home so i can gather those milivolt signals in the air more cleanly.

Philco 46-1226 Radio

Reply #5 –
a couple more with heat sync and in the chassis.

my aftermarket dial glass is perfect,,

Philco 46-1226 Radio

Reply #6 –
i watched an old westinghouse training film for vacuum tubes because ,, well,,, the generation gap in that i never clearly understood what they did because they appear in so many different shematic forms.

once i watched the film, it was amazing and simple to fast track a person inside 30 min on whats going on in there. 
They can do six things,, 5 are defined but the sixth one is somewhat infinate.

fast forward to a recent IBM training film i think from 09',,  from what the speaker was saying, apparently three is not a single electronic part availble today that can do all the jobs a tube can.
size was the reason to make them not so useful anymore, other than that one minor infraction, they would still be in use today.

this chassis draws 80mA at 120v. 
can be fed with DC as well with some tricky engineering since it spends a lot of energy initially converting to dc.

Philco 46-1226 Radio

Reply #7 –
thre is a big tall resistor in the back with a suspect looking pigtail copper roll. That is one of my mods.
this radio needed a 300ohm resistor placed on the secondary of the power transformer to allow for the newly invented PM speaker.

this particular resistor gave philco many troubles because it was always burning out.

now basic electricity can help us find the right wattage but this is where it gets to an area i have never ever had to deal with.......

the one line looks like this.......
800v secondary with center tap (400vAC / 400vAC).
one 400Vac leg to: one side of the big green resistor.
Other side of big green resistor goes to the two filter caps cans each being a dual 40uf/25uf 400v type.
the above prepare the ac for the DC converstion.

This resistor is smack dab in the middle of the rectification section.

my voltage drop across this resistor measured readings on both the AC and the DC scales but everyone on the Philco forum said to check what the dc voltage drop was across this resistor to size it for wattage.

i came up with 48vdc drop across the resistor and at 300 ohms needed per philco well you can see that  E^/R = watts which is about 8watts.

well this resistor was getting too ***HOT*** with the 10watt i installed and at 300 ohms.

since all the old timers told me it was a common problem, and at 300 ohms it introduced too high of a voltage to the push pull 6k6's, i calibrated it.

since the resistor is in the middel of the AC / DC converstion,, you have to do a complicated forumla blending the AC and DC effects this resistor suffers from.

my big green resistor shown is a 25watt 611 ohm which worked best.  It gets to about 125deg even with my pigtail copper heat sync thingy.

my point here is that ohms law applies,, but ... in some cases it dends on where you are in the circuit as to how you size for heat disipation.


i am still learning about this stuff but ,, again my point here is that the basic ohms law did not apply in this case.. very odd how something with 48vDC and 600ohms sized to 25watts is still "telling me" ,, "I'm too small,, please insert 50 or 100 watts here".

Philco 46-1226 Radio

Reply #8 –
Yee Haww, great job Scott...

I wouldn't have worried about the heat sink on tubes, these sets ran for years without them... I'd be more worried that unequal expansion of glass and metal sink would crack the glass... Tubes can be rebiased to drop their operating temp...

As far as 6K6 lemme kno if you need some, probably have 12-15 good used ones around here...

Philco 46-1226 Radio

Reply #9 –
yes i considered that in the design,, and you cant see it from the picture so ,, here is a quick etch and sketch of what that strap is actually doing.
its able to expand and contract.

the only big question mark is the "rate" of expansion of glass as compared to steel.
I would only "think" that glass is harder than steel and expand slower, meaning the steel is always ahead of the glass during heating and cooling???????

Philco 46-1226 Radio

Reply #10 –
Gary at "Play things of the Past" up in Medina ohio has been really great.

He operates very old school.  You have to open up HIS page.
Look through HIS inventory which is accurate
copy and past HIS enventory line into Your email to him.
you have to include "RADIO" in the subject line of the email.

his prices are very very very low.

you should check it out.

he closed doors on the Cleve. shop and now operates by email only,, and the whole shop and inventory is up for sale,, yet he keeps supporting anyone who wants stuff he has.


I have all the "orginal" Philco marked tubes except for the 7AF7,  i put these originals back as spares.

i would like to have spares of my spares... LOL.


If every you need any resistors ,, make me your first call.  I am being honest when i say i belive i have several thousand.  lots of Vibrators as well.

Also,, i did my first ever Locktal repair where i had a carbon flash!! 

it was very interesting that all three of my major issues getting it going were all either problems i had no knowledge about to preven or were simply shop manual errors or other peoples screw ups.

i took it one part at a time one day at a time.

I learned so much about what i didnt know though,, to be honest there is a huge amount of lost information about electronics pieces parts in general that todays generation would not "know" to look for.  A for instance is running across a resistor with stripes and the color of the resistor is brown. 
well ,, the resistor "BODY" is the first significant digit,, then the first band is the second significant digit. !!!

or bumble bee capacitors that look exactly like a resistor with all the bands  and shape.

or ,,, schematics that show something like .05MM for a capacitor,, what they mean is .05uF.  the use of capital "M"'s would mean Mega+Mega to us but it meant "milli + mill" to you all back then. 
I suspect in the 60s there might have been a global restandardization as to how this stuff is done,, as to get rid of interpertation errors.

Philco 46-1226 Radio

Reply #11 –
That'll probably be OK, guess time will tell...

The 6K6 or 5Y3 were never mfg'd in metal configuration but a pair of metal 6V6 can be subbed... 

Also a metal 5Z4 can be used for 5Y3...

Metal tubes are usually cheap at the tube vendors or even on ebay(where generally the resellers that cater to audiophools run prices up)... They are certain that some brands sound better than others, of course it's always the ones in short supply... Funny thing is no tube manual that listes specs ever claimed to be better sounding than the next manufacturer's product...

Philco 46-1226 Radio

Reply #12 –
another thing i would not have known and could have easily made a rookie mistake.......
I mentioned in passing on the philco forum that i was going to get rid of all that banjo strung wire that going diagonal ,, here to there and random looking.  My plan was to make a wire harness with primary and high voltage along the chassis in one direction and all the other wiring around the other side of the chassis.

BIG MISTAKE<, glad i didnt this.
someone said
"those radios were made and soldered and then they were frequency aligned.  If you lengthen those wires, you are going to throw the alignment out the window because no two identical radios aligned "identically" .  Those wire lengths and such are an important ingredient to the way the radio is tuned."

Philco 46-1226 Radio

Reply #13 –
Quote from: TurboCoupe50;460849

The 6K6 or 5Y3 were never mfg'd in metal configuration but a pair of metal 6V6 can be subbed... 

Also a metal 5Z4 can be used for 5Y3...

QUOTE]


My hallicrafters has metal cans on some of the tubes,, i was wondering how the heat gets "off the tube and to chassis,, cant see how that happens since heat "moves up" and some metal cans i see have a clipping attachment at the base to touch chassis.

do the metal cans run cooler or do they simply protect your hand from getting burnt and traps the heat?

Philco 46-1226 Radio

Reply #14 –
The metal tubes have no glass, well other that sealing button in bottom, those tubes actually radiate heat better than glass...  Metals basically lost out as it was cheaper to mfgr all glass types...  Metals were a RCA/GE invention, AFAIK Philco never used a metal tube period, as RCA & Philco despised one another... The Loktals that are in your radio were a Philco/Sylvania invention, are better in high frequency circuits than the bakelite based octals...

As far as wiring leave as is, probably wouldn't cause a issue at regular AM freq but shortwave may well be adversely affected...