Antique Radio Repair part4! RCA 810K

[magicbrainman]

these models are terrible about the plastic dial cover shrinking, cracking, warping.

do not move south to hot climates, keep it away from any possibility of sun exposure, and keep your house climate controlled. If you have any spare plastic dials for this one or have had a repro made, please contact me magicbrainman on youtube. Also any part you need for this radio please inquire

[smeezekitty]

@Lockemeister

The B+ is around 305v.

[Lockemeister]

@smeezekitty OK, now it get complicated

yoou need to google the words 42 tube data. The 42 tube is the same as a 6F6. You might could try 6F6 tube data too. Is this s single tube or push pull Amp with 2 tubes? The plate voltage is different for single verses push pull. You need to know the grid volteges too. If it's to ohard to do don't do it, be safe not sorry. Keep one hand in your pocket. If you are unsure have a professional do it.

[Lockemeister]

@smeezekitty i'll send you a link to a 42 and also a 6F6 tube data sheets. The single tube amp plate is like 250 volts and the push pull is around 350 volts. Some types of 6F6 push pull is 375 volts for the plate. To be sure you need to check the grid volts too. But if you are unsure leave it to the professionals. I ALWAYS keep one hand in my pocket when probing. These 6F6 tubes do run very hot when in normal operation.

[Lockemeister]

@smeezekitty you also need to find the schematic information for your model number. Try nostalgiaair.  org

[smeezekitty]

Our voltage never gets runs 118v-120v, no higher so i don't think thats the problem.

Also the power transformer is very cold, maybe yours has some shorted turns?

[Lockemeister]

@smeezekitty I ended up lowering the input voltage to around 114-115 volts or so and the radios transformer just gets warm now. I think it was running at the edge of design tolerance. Tranformer would get hot after about 2 hours of usage at 124-125 volts. Now after two hours it's just warm.

[smeezekitty]

What is the temputure of the output tubes (6F6?)?

I am restoring a zenith and the output tube gets too hot to touch in 2 min.

[Lockemeister]

@smeezekitty That's a good question. I do not know. I have never taken the temperture of the 6F6 output tubes. However, they are amoung the hottest running output tubes. I suggest getting the parameter table for the 6F6 tube, its the same as the 42 output tube and determine if your plate and grid voltages are within specs.

[Lockemeister]

@smeezekitty Check out my video on voltages. I ened up using an autotransformer to lower the voltage to this radio about 10 volts. I originally had 122-124 Volts input now I have 114-117 Volts AC input. I got the plate volatages to the 6F6 to about 365 Volts which is a nice voltage. Previously it was barely in spec at 395 Volts.

[Lockemeister]

@smeezekitty I'm not saying you NEED to lower the input AC voltage. I had to because after a few hours the radio's transformer was getting boarderline hot. If your Plate voltage is too high, or the grid voltages is wrong, you have to check the circuit resistors first to see if they are in tolerance. If the tube is turned on too much it will run hot.

[Lookup2Wakeup]

Nice job, 5*

[Lockemeister]

Thank you sir. I figgured out I need for this radio to lower the input voltage to 115 Volts. I think running at the total upper limit of 125 Volts is at the total limit of the design of the power transformer and the field coil. I think I will make a bucking transformer to lower the voltage to 115 volts.

[raymanretro]

Beautiful set, I understand completly about the cats!!

[Lockemeister]

Thanks!

[musicman0150]

Very nice radio and video series on putting it in newlike operation. For a 12 watt radio, that sure puts out sound like today's 100 watt units. Is that strictly a radio or can you connect other devices to it, like a CD or cassette player; to simulate old time radio broadcasts? Did you ever figure out what was causing the right display to not work properly? Gary

[Lockemeister]

Thank you. I did find out about why the right display didn't work. The display is cable actuated with the cable attached to a cam which is attached to the shaft. The cam was made out of what was called pot metal. I must have tightened the 2 screws that held the pot metal cam to the shaft slightly too tight and the pot metal cracked. Actually the pot metal disintegrated. I saved the broken parts and perhaps one day I can figgure how to make a new one. Maybe a scroll saw could be useful.

[geeflyboy]

What bands does it have MW (BCB) AM but it has SW bands. Do you know the Freqs.

[Lockemeister]

From the official RCA documentation, they list the frequencies as follows:

BC = 530-1,720 kc

Medium Wave = 2,100 - 6,800 kc

Short Wave = 6,800-22,000 kc

kc = kilo cycle

now they use KHz - in honor of Heinrich Hertz.

[ainamen]

Hi, great radio.

I'm recaping an old Emerson record player but I couldn't find the schematics... The problem is that there is something (I think is a resistor) like thin wire around a white plate and it had something red, clay-like around it (I believe is to protect from heat ) this part is cracked and there was something written, but it wasn't enough to read. Do you know what that is or if I can measure that (once the wire is not broken), so I can replace with something more reliable? Thanks

[1947Fordcar]

I had one it caught on fire and destroyed it.

[Lockemeister]

Sorry about your loss.

I noticed some power resisters get fairly hot. I used 2 watt units instead of the 1 Watt originals. Maybe this will be better. Old rubber wiring is not what it is cracked up to be. Infact half of the wiring was cracked. I either replaced, heat shrinked with clear heat shrink, cracked all the insulation off and THEN heat shrinked, used Super Corona Dope, and sometimes GE Silicon. I also fused it with a 1.25 A fuse and unplug it when not in use. Hope this all works.

[Lockemeister]

I had to up the fuse to 2 Amp.

[OldTimeRadioGuy]

Great radio series! Not sure if you know this but be careful with old radio chassis as many were cadmium plated which likes to from a yellow-greenish dust that can make you ill. You can read about it more by searching the AR forum site and how to take care of it...

[Lockemeister]

Thanks for the tip. I was wondering about the pretty greenish color. Good think I didn't lick it. Anywho, i'll check out the AR forum.

[blasttapes]

Does yours have the glass over the dial? If so, you're a lucky man!

[Lockemeister]

If you look close, you can see the plastic around the dial is busted. The radio had fell before I have obtained it. the plastics of these models shrink after time also. the glass was busted, and I had a glass shop cut a new glass to fit it. Cost $7.50 to make, not a bad deal!

[Lockemeister]

I had the original glass, but about 25 percent was busted out of one corner. I took it to the glass shop and they had a piece of glass that was slightly thinner. He was able to make a new glass window by tracing the old glass and extrapolating out the broken section. However, the old glass had a very slight green tint to it, while the new glass does not. The glass guy never saw the type of glass that was in the radio originally.

[blasttapes]

I still can't get over how quiet yours is in between stations. I need to get into mine someday. You need some more light so we can see that cabinet! We need to hang on to our 810's- they're as rare as uncooked steak!

[Lockemeister]

Yeah man, the light from the windows was fooling the camera and it was making the image too dark. the cabinent is all original has does have some dings on it. Character dings I say! Speaker cloth is replaced with something I got by looking at 4 different fabric stores. No reproduction cloth ismade for the 810K original cloth. They did have some RCA repro cloth for other models, but not for this one. NOw the 816K, now this pup is a rare beast. I'd like to get my hands on one of those.

[Lockemeister]

my biggest problem is remebering the volume control is on the right. it's more intuative to be on the left!

[desertbard]

Still has nice bass when on brilliant. Nice work. Antennas are outdoor beasties.. Let one out..

[AllAmericanFiveRadio]

Wow what a neat cover. Plays great! You'll have many hours of fun listening.

[Lockemeister]

Thanks! As long as the broadcastors keep using anaolog systems and don't all go to some crappy IBOC digital system!