I have 2 TVs.

This one was my great grandparents, and it is unrestored.

Can you date this? It has a service tag of 1960 from 2 or 3 tubes replaced.

I still have yet to see one like this silvertone.

I cant upload the pic. crap.

The jpg is 600kb, any ideas?

Welcome to AK!

The picture is too large I think, you need to shrink it down a bit. I don't know the size limit but less than 100k is probably OK.

If you need some help with that E-mail it to me and I can fix it with Photoshop and send it back to you.

Eric

i dont have a program that does that.

i got it. i forgot my camera has a built in editor

That's a unique looking set. I like the way the channel selector is in the middle. Is that one the Silvertone? Look on the back of the set and see if you can find a model number. That would help us date it.

Looks like it could use a filter cap in the verticle circuits.

On your camera, you should be able to set it to 640 x 480 before taking the picture.

You said you have 2 sets... what is the other one?

I found a Silvertone like that at the dump one night. It cleaned up nicely and I nearly got it working one winter. The chassis has to be the vbest design ever. The whole thing is flat and is very light and easily removable. The only downfall is the series circuitry and selenium rectifiers. They must have a lot of vertical trouble. I see yours has it and mine did to. Mine had no vertical sweep. I forget what I did but I got it working. My rectifiers were heating up last I remember. It would have been an easy re cap. I dont know why I lost interest but I did and gave it away to a collector in a different income bracket than myself. More income= more space. I do this from time to time to make space for newer projects. Sometimes like now I regret it but at least the stuff I cull goes to a good home and stays in the collector circle. The set is from 56 or 57 I believe. I do remember an ion trap on the crt which tells me it couldnt be much newer than that.

yea, its the same thing with mine.

If i first turn mine on, it works perfect.

After it runs for a little bit, the picture will slowly shrink, it looks like a scrunched 16:9 when it happens.

If i keep a boxfan blowing on the chassis, it stays full raster.

Here is my other one:

http://linux.hamilton-city.k12.oh.us/~mbates/project1/tvrestoration.html

I wrote a whole website on my other one.


(there is an AVI of this set working, PS this is the one with the bad yoke, you can see)

im sad to say this, but on my silvertone, I have to use a CRT brightener to obtain a good picture.

Then again, it may have alot to do with the original caps too.

My emerson has NO diodes whatsoever.

this emerson, as you noticed was completely destroyed in shipping.

I found a 16rp4 with ion trap untested for 15 bux/

the original tube shattered, thus clipping the leads on the yoke. they are still clipped/cut, and no way to fix it. (hence wavy picture).

I took a gamble on the tube, but hey, it worked!

there is a sticker in the back of my silvertone, it still has all of its original stickers, Hell, i still have the reciept from it where my great grandma gave it to me!

she paied about 2 grand for it new, in chicago.

just came out, but if she would have waited, another model better than that prolly surfaced and the prices prolly dropped considerably.

BTW they are both still alive and well. one is 90 the other is 86.

Im 18 BTW. I restored that emerson when i was 16.

Does the Silvertone use a 21" CRT? Do you have a Sam's Photofact for it?

i dont have a photofact, altho i wish i did. I have to resore the vert circuitry,

I forgot to mention there is a sticker on the back that said "All new aluminized picture tube".

Another thing i forgot to mention, Why does the HV arc from the metal brace holding the tube to cabinet, to the aquadag?

it arcs like crazy, and sometimes runs a continuos blue flow of electricity up and down that brace to the tube.

If i duck tape that brace up, it will calm down.

I cant see the sticker on the tube. (no flashlight).

But, if it is a 21" its the same size of todays 27" tubes.

For the arcing, there should be some kind of grounding device... usually a spring or metal strap traveling across the funnel of the tube... that would keep the aquadag grounded. If the ground is not there, you might get juice jumping around in there. :eek:

If you can get a model number off the chassis, I can see if I have the sams for it. Sears usually had a number stamped somewhere on the chassis. They're numbers really never followed a pattern. Sometimes they were 3 digits, sometimes they were 8 digits. IIRC, they did use a metal tag that was usually rivetted to the chassis, but that might only have a serial number.

the aquadag is grounded.


both the dag, and that brace is grounded.


hmmmmm. and that brace arcs only to one side of the dag. Guess where that side is, the anode lead.


528.38503

Is the surface clean? If there's a lot of dust on there, it could conduct the HV.

That number brings up Sams 329-13. Will go check my files.

i cleaned teh dust off.

You're in luck kiddo! I have duplicates of this particular Sams, so I'll just send you one of these. PM me with your address and I'll get it out to you.

Looks like your sets uses either a 24YP4 or a 21ATP4. Was also noticing that you have those selenium rectifiers, but your set uses a dedicated 6 volt filament transformer to give you parallel heaters.

If all is clean and properly grounded, you shouldn't get that. There are only 2 other things I can think of...

1. Examine the dag coating where the grounding strap or spring makes contact with the dag. The coating could be worn off at that contact point. If it is possible to re-posistion the spring or strap across the dag... even moving it just a half inch one way or another... that may help. If a spring it used, sometimes they get rusty. That may also cause a poor ground to the dag coating.

2. The route you HV anode lead takes from the cage to the box... does it lay against the dag coating somewhere before it gets to its connection? This one is somewhat of a long-shot, but wouldn't hurt to check. If they anode wire is up against the coating somewhere AND the anode insulation is breaking down where it touches the dag, this could be causing a problem. Seems this would be less likely, but we've all seen stranger things. OR, since you mention it only being on that one side near the anode lead, perhaps that is where the arcing is actually coming from.

Just some thoughts there... hope they help some.

The date on this Sams is September 1956, so your set was probably from 1955 or early 56.

Are you sure that the crt mounting brackets have a firm connection to the chassis? You can try taping some aluminum foil to the aquadag and running a wire from the foil to the chassis to improve the grounding.

Hey mbates14, Great sets, AND I checked out your site on the restoration of the other one. I'm just amazed when younger people are interested in this vintage stuff now. My Uncle had a repair/ sales shop and I LOVED tinkering around with the older sets. I was about 13 when I fixed my first one! (I'm 38 now) I could diagnose the problems pretty good, but if it was beyond anything simple (tubes and such) my Uncle worked on it. I wish I had paid more attention back then and learned how to solder worth a crap, because when I get a vintage set now, they pretty much have to be working. I still like the old tube stuff, and am amazed when you younger guys take interest as well. I have a few friends younger than me (but older than you) that are amazed when I fire up some of the old sets with the backs off as they had never even seen a tube! Anyway.... just wanted to say "hey" and to keep having fun on your restorations. James

anything tube always did fascinate me.

I dunno why, maybe the warm glow and sound made somethign tick in my brain.

Im not one of those teenagers that goes illegally and get drunk, and smoke, and go and doo all the stupid shit that teens do.

Im quite the opposite.

I love electronics, And i engineere amplifiers, solid state ones that is.

I built tube amplifiers, but only based on schematics.

The dag is grounded, and the wires arnt deteriorating.

its wierd.

I noticed too, that in the dark where the anode cap is, you can see blue streams of electricity down inside the glass comming off the anode connection. and a little bit to the right, there is the metal brace it arcs to teh dag.

I think the dag is deteriorating, and it looks like it is.

I have no idea how or what to recoat it.

BTW

I restored my principals 1947 Zenith turntable radio

It works like a charm!

i recapped it, but the main reason for the failure was the AF plate load resistor, in other words, the resistor that connected the AF/driver tube to the B+ source was nearly opened.

But, it doesnt hurt to recap.

also, its modern, but VFD displays interest me too.

I think because its also a tube, and they produce cool text and grafix.


I have a Noritake custom graphic VFD GU128x32-311

but, I have NO IDEA how to program C++ or for that matter, i dont know how to create drivers to interface this to the PC.

outta luck there, but I do know how to code PHP, mysql, and some other languages.

I know this is kinda unrelated.

Just thunked of something, don't use duct tape as it's probably conductive.......they usually have some aluminum and other powdered metal in the silver part.

I've seen wacky ass hot rodders paint their engine silver and proceed to get it all over the spark plug wires----then they'd bring it to me to finger out why it runs so bad.

Ummm, does conductive paint and spark plug wires sound like a good combo to you? Spark scatter everywhere! A new set of wires and all was good again.

Anthony

I would try cleaning the area around the anode connector with a little denatured alcohol (discharge it first!) even thought it looks clean now it might have some small carbon tracks.


Eric

ill say one thing, they dont make them like they used to.

Back in those days, they had some interesting designes i wish they still had today.

Now, they are just plain looking japanese jucnk.

in todays circuitry, one little component can cause a complete expensive catastrophe.

tubes, i bet my set with the strong tubes i have in there now, and the caps that are rated lifetime, I bet that set will last another 50 years.

try to get that kinda time out of solid state garbage of today.

it already lasted 50 years, lets last another round of 50 years.

And my silvertone, it is unrestored and it still works! take that and shove it up japan's ass. LOL:D

my 2 cents

Not to defend the new stuff but in many ways the older sets were just as prone or in some cases even more prone to catastrophic cascade failures as they didn't have anywhere near the integral protection.

Didn't I read somewhere a slew of suggested mandatory fuses on certain vintage sets for this very reason? A shorted tube can take out the chassis and vice versa.

Anthony

shorted tube?

tubes can short? hell, i didnt know that.

I havent had it happen.

Anyway, for the most part that type of catastrophy is fixable, because most of the parts can be testes.

Try that on todays electronics, you cant test an IC.

My set isnt fused anywhere except for the damper area, that has a special fuse.


Should i fuse it? Where should I put fuses?

I've been lucky... only had one tube short on me. Was a 35z5 rectifier in a late 40s radio. WOW it really got my attention when that thing shorted!

Mike, you can develop a heater to cathode short, which would let your AC filament current get into your B+.

For your Silvertone, you could probably do good with a 2 or 2.5 amp fuse after the power switch.

Your schematic just went to the mail man. It's on its way.

I recieved the schematic today, and man do I really appriciate it!

I notice that the cabnet is not the same? hmm.

anyway, its a 24yp4, it has to be.

I measured it with tape measure, it appears to be about 25 inches.

Anyway, I thought they were going to be like a copy run off a copy machine like justradios.com does.

no, its the original folder/copy from that day! THANKS dude.

I think it might have something to do with the rectifiers, because my vertical will shrink the longer it runs. if i blow a fan on the bottom of chassis, the picture will be returned to normal.

Anyway, the aquadag is comming off, because everytime i rub my finger on the dag, it is black.

How do i recoat a CRT? one of my friends said it was a magical wonder to recoat those.

gimme some ideas. Thanks!

When I find that I have multiples of the same schematic, I just send out the extra copy instead of scanning a copy.

The photo on the front is different from yours because they used the same chassis in many different cabinet styles.

If your blow on any parts to cool them down and it makes a difference on the picture, that's a good sign the part needs changing.

I returned today from Dallas... was picking up my 2nd 21FBP22 that they previously tried rebuilding, but had to do it again because they found the gun to have a short. I had inquired about the dag paint, and he told me next time I come up to bring a milk jug and he'd fill it up for me. They buy it in drums I think. He was not sure where to get it in smaller quantities. Now days, they use a water-based paint (used to use laquer years ago). I'm not sure where to buy it, but they mentioned trying a paint shop... said that the paint is pretty simple stuff.

Anyone else got any ideas on where to get the paint?

Charlie, check the early color forum, I posted a link to two 21" tubes, possibly rebuildable duds, and they are in Texas!

MIKE: The Aquadag can be recoated using G-C Electronics part# 10-4807 conductive paint. It comes in a 12-ounce spray can available for about $27 through ACK Radio in Georgia and marketed as an EMI/RFI shielding product. Before recoating, you'll need to remove the tube from the cabinet, remove the yoke from it, clean the tube surfaces with denatured alcohol, and mask it. Discharge the dag capacitance before handling the tube. Use great care to not drop, strike or scratch the tube during any part of the handling of it. The glass construction and high vacuum make for a spectacular and dangerous implosion if the glass envelope breaks since the tube surfaces are actually supporting tremendous atmospheric pressure. The faceplate alone is under more than two tons of pressure from the atmosphere. Set up a "paint booth" in a garage by obtaining an old large-appliance box and cutting it to leave the bottom and three full sides which will define an area where you can leave the tube unattended overnight to dry without it being damaged. The booth will also stop any overspray from getting on floors, walls, etc. Mask the faceplate of the tube with a sheet of plastic and tape the plastic to the tube with a continuous strip of tape that lines up exactly with the edge of the original dag border around the funnel-to-faceplate seal. Set the tube face-down on a thick, soft surface like an old blanket folded into about a 30" x 22" rectangle. Next, wrap plastic around the tube neck all the way up and secure the wrap with electrical tape. Run tape around where the original dag ends to mask exactly along the original border adjacent to the neck. You'll also see a big, circular void in the dag coating at least 4" in diameter (usually close to 6" on those 24" tubes) around the anode connector. Thoroughly clean the glass (again) around the anode connector with denatured alcohol to remove all the carbon trails. Inspect this area with a magnifier if necessary. This will be the most critical region of the tube surface since it's directly adjacent to the anode connector and about 15kV. Mask this circular area with electrical tape, again taking care to follow the original factory border. The clearances are critical and usually specified in the original design drawings of the tube with a tolerance (+/-1/8" to +/-1/4" typically). Verify an ambient temperature between 60-80 degrees Fahrenheit as that's the optimum range for application of the paint. Shake the dag spray for at least a full minute to make sure it's thoroughly mixed. Spray from a distance of 8" to 12" from the glass and keep the spray moving to form a nice, uniform, thin coat. Turn the tube around by rotating the blanket it's resting on if you're having trouble getting to the opposite side of the tube. Once you've got a nice, even first coat, let that dry for 1/2 hour to 1 hour. Spray another thin, uniform coat and let dry. Use a third coat if desired. Turn the "booth" around with the open side against a wall and mark the box "CAUTION, KEEP AWAY", "WET PAINT", etc. Let dry overnight. Again, handle the tube with great care. The structure is very strong to support all that pressure, but tripping over a crack in a driveway while carrying it and dropping the tube will almost certainly shatter it. In my "young and crazy" years, we took "dud" picture tubes into a large, open field on the few extra acres of land my grandparents owned behind the family business where we did our target practice and shot these 12" to 24" tubes with high-powered rifles and shotguns from about 50 yards away. The noise was about equivalent to 1/4 to 1/2 stick of dynamite. It wasn't unusual for the implosion of a 21" tube to hurl palm-sized chunks of glass 20-30 yards from "ground zero" and displace loose dirt leaving a "crater" under the spot where the tube was sitting. Afterward, we vacuumed the area with a miniature version of a street sweeper that was normally used to sweep 6 large driveways and a parking lot on the front few acres. Basically, it was a cross between a lawn tractor and a vacuum cleaner. As I remember, there was quite a mess to be cleaned up after an afternoon of tube-shooting. I've never seen a tube "blow" in a repair shop, but I heard about an incident when a not-too-sharp tech made the mistake of cutting the tension band off of a 25" tube to remove its mounting lugs. Apparently, he heard the glass start to crack just in time to get safely out of the room before it "blew" and found chunks of glass embedded in the walls after the blast. From the oldtimers' telling of that story, it seemed amazing that no one was seriously hurt or killed.

I just re-dagged a 10BP4 for a customer who bought it from an eBay seller who had wrapped it in adhesive-backed bubble wrap which was placed with adhesive directly against the dag. I recommend wrapping CRT's for shipment using an inner layer of non-adhesive bubble wrap and then it's ok to use the adhesive-backed stuff as outer wrap so it won't touch the dag.

JSTOUT: I'm also 38. My son, age 14, will be recapping his first tube radio soon. Tim has been playing guitar for a few years and has a strong preference for tube tone. He's been helping in the shop, mostly on lift-and-carry tasks that require two people like unboxing 630TS cabinet/chassis assemblies to get them ready for "pulling" the chassis for recapping.

I've been "technically curious" since childhood. I've traced everything back to the explosion of the plug of a defective box fan in my hand at age three. Tim's experience is similar, having turned on a large guitar amp while using it to support himself as he was learning to walk and then run screaming out of the room when bumping it caused the reverb springs to bang together and the amp to emit a loud bang and ear-splitting howl. To this day, he remembers that incident.

How far will a can of that paint go? (how many crt's?) I have 3 or 4 in need of recoating. I work with all manner of automotive paints every day but know of nothing that fits this description; I've thought about trying to mix together some charcoal dust with paint to make a brush-on coating. 3M makes a powder we use which consists of limestone, activated charcoal & carbon black-I wonder, if mixed with a binder of some sort, if this would be workable?

I'm not sure at this point about what its coverage is, but my best guess is that its square-inch coverage would be consistent with a similarly-szed can of ordinary spray paint. Since the surface area of the dag coating on a 1940's tube such as 10BP4 and that of larger 1960's tubes like 24MP4 are widely different, I would not be able to predict results that closely. A rough approximation of the coverage of a can of paint less a reasonable estimate of overspray divided by a rough approximation of the dag surface area of an average CRT divided by two coats would be the setup for the calculation.

N= number of tubes
A = total coverage (square inches)
L = overspray loss (percent)
T = average CRT dag surface area (square inches)

N = A*(100%-L)/2T

A can of spray dag should do at least 6 medium size tubes.
The story about the tech cutting the shrink band to remove the ears to make the tube fit a different mount is TRUE, I herd it happen, sounded like a shotgun blast, he had console on it's face and was lowering tube into it, tapped the tube on the floor when it was fully in - BOOM - was a miricle that the did not get cut as he was leaning over the cabinet when it blew. This was done by at part time used TV shop at a local inside flea market, he was only open on weekends. Nick named "Brand X" he closed up shop the next week, learned his lesson the hard way.

Originally posted by jshorva65
Basically, it was a cross between a lawn tractor and a vacuum cleaner.

Trying to invision The Kubota Dirt Devil :D

The story about the tech cutting the shrink band to remove the ears to make the tube fit a different mount is TRUE, I herd it happen, sounded like a shotgun blast, That makes TWO such incidents, as the one I heard about had happened in a local shop and the walls still had the gouges where the glass had dug in. I worked there for about a year between college and my first contract engineering job.

Our local newspaper had a story in News Briefs headlined "Texas Woman Killed By Exploding Television" during the first week of July, 1986. The story, as I remember it, was that a violent domestic incident between a husband and wife involved the throwing of a television set. Later, the wife's sister came over to help her clean up the mess. She picked the TV up off the floor and BOOM! She died about an hour later at an area hospital of blood loss from massive cuts to the face and neck.

Originally posted by Charlie
Trying to invision The Kubota Dirt Devil :D More precisely, it looked something like an oversized golf cart with a vertical-axis rotating brush on each side and a wide horizontal-axis brush underneath. The vacuum system caught whatever the brooms kicked up and deposited the debris in a big black plastic container at the rear of the machine. The controls included a steering wheel, throttle and brake pedals, FWD-N-REV automatic transaxle selector lever and electric start. There were also levers labeled BROOM CLUTCH and VAC CLUTCH. I vaguely remember its engine being 2-cylinder air-cooled 4-stroke. Based on my limited small-engine experience, it was probably 16-20 HP ... probably an 18 HP Wisconsin or similar. Usually, it was parked in a pole building behind my uncle's place next door. It also came in handy back behind Uncle Mike's picnic pavilion and swimming pool around the 4th of July ... lots of spent fireworks shells to sweep up after the annual bash. I guess the term "upper middle-class rednecks" sort of fits my background. Most everyone either worked at or was retired from some sort of manufacturing job or owned a small business. Back in the 70's, we had access to some pretty impressive fireworks, too, thanks to a few independent "owner/operator" truck drivers among us who drove over-the-road across the "lower 48" states. The "half sticks" they'd bring back from a run would blow a 2- to 3-foot diameter crater in loose dirt.

here is the problem charlie.

Which part. Thats the question.

I would start to freeze spray the seleniums, and the resistors, BUT I dont have any local suppliers.

I would like to build a tube AM transmitter. I been googling all over, but i want a simple, easy to use schematic.

I have some tubes, and a 700VDC power transformer being waisted.

an 807 is just collecting dust also. I would like to build a good transmitter, about 100mw or so. 100mw being the legal limit.

(another off topic thing, as im great for doing that :dunno: )

The reason I ask, is because I have a couple tube radios, one being a turntable, and one being a portable DC tube radio. (7 9v batteries btw).

I had a SS transmitter, but i think they sound like sh*t and I like tube better anyway. ;)

Speaking of methods of cooling stuff off for testing porpoises:

Back in the days of carburetors and cheap Freon we'd cool off the choke with a blast of R12 so that it could be set properly.

Sometimes a entire can of Freon would get used up to make sure the choke was working properly (cool off, start engine, check operation, repeat).

That's my personal contribution to the hole in the ozone. You're all quite welcome. Ahhh, blissful ignorance, those were the days!

Anthony

Charlie, pull out your copy of my TV schematic.

please correct me if im wrong, which i might be, but after intense studing of my vertical section, and that schematic I have drawn some conclusions:

My vertical linerity is sorta bad, and the vertical will shrink after it runs for a little bit. its a slow shrink, kinda like a sunset.

so, It cant be before the vert output tube 6s4, because it would start to roll, or loose sync. The picture stays locked completely.

it HAS to be the output. I did notice that the vertical linarity control is run through the cathode of the output tube 6s4.

well also, if you look there is a little paper wrapped electrolytic 50uf, comming off the same cathode to ground, I got my eyes on that cap.

well, here is where i may be wrong, but there are (2)2.2meg resistors in that circuit, one providing volts to the grid, and another comming off the grid back to ground.

well, that cap could be dried up, and run the bias off, because i think that paper 'lytic works the bias on that tube, (this is where you need your copy). well, to the point:

i think that lytic is dried, so it could throw the bias off, and make the tube run a little hot, and then that would be the source of my linarity problem, because the linarity is controlled through the cathode, and that cap could be gone, throwing off the cathode bias, (hence) the linarity is off.

This is causing the tube to run amped up, and then the 2.2meg resistors are overheating, dropping the volts on my grid causing low output, hence insufficiant vertical deflection. (this is where you correct me if im wrong via schematic :dunno: ).

I have come up with these conclusions by studying the schematic.

Any opinions, or facts would be considered, im just studing to find out possible problems, and required solutions (replace lytic cap). no ESR meter, too expensive.

Another conclusion I considered, would be the cap breaking down under load, lowering the tubes output.

Mike,

The first thing I would try changing is lytic C2-B on the cathode of the verticle output tube. It has been my experience that this is usually the culprit for most of my verticle shrink problems... especially in color sets. Just for shits & grins, change C62 and C63 as well. While working in this area, check those resistors you mentioned to verify they are within tolerence.

if you look there is a little paper wrapped electrolytic 50uf, comming off the same cathode to ground, I got my eyes on that cap.
Note: According to the number you gave me the other day, your TV has chassis 528.38503. The diagram shows C2-B as being 50 mfd. But... notice on page 14 in the capacitor parts list... there is a note by C2-B. It says that your chassis should use 100 mfd instead of 50 mfd. Just wanted to make sure you caught that. When you follow the circuit in your set, double check this to make sure.

IMO, you should just go ahead and change as many of those caps in your set as you can get. It looks like your set uses those paper-wax and plastic tubular caps for couplers, and those are always prone to failure after 50 years. Same goes for your electrolytics. You'll find that in most cases this will pretty much correct almost all of your set's quirks, and also it will save you time in the long-run. I'm sure that most everyone here will agree with that.

You don't want to use an 807 for a part 15 unlicensed transmitter...that is a 25 watt tube at least. The FCC will be calling.
Check out Robert Casey wa2ise's web site for info about tube AM micro-transmitters. You can use parts from an old AM tube type radio.

Originally posted by Chad Hauris
You don't want to use an 807 for a part 15 unlicensed transmitter...that is a 25 watt tube at least. The FCC will be calling.
Check out Robert Casey wa2ise's web site for info about tube AM micro-transmitters. You can use parts from an old AM tube type radio. As Chad pointed out, if you want to build a tube-type transmitter, the 807 is way too much for a Part-15 unlicensed unit. There was a design for a Part-15 compliant AM transmitter published in a Ham Radio book some time ago which I seem to remember used a 6A8, 6J7 and powered by two 6.3V 2A transformers connected secondary-to-secondary with a 6X5 or some similar rectifier tube. The first transformer stepped-down the 120V line to povide a 6.3V heater supply for the tubes and to also be stepped back up to provide an isolated and energy-limited 120V source to be half-wave rectified and filtered to meet the unit's B+ requirements. You could redesign the unit using 6.3V single-ended octal equivalents (6SA7, 6SJ7 and keep the 6X5) or use 12.6V tubes with two 12.6V transformers (12SA7, 12SJ7. 12Z3). Miniature types 12BE6, 12BA6 and 12X4 would also work well with a 12.6V heater supply.

AES sells a transformer with 115V primary, 125V 15mA and 12.6V 300 mA secondaries (AES #P-T442 for $16.95) which would power a transmitter using either a 12SA7 and 12SJ7 or 12BE6 and 12BA6 tube complement. Since the 12SA7 and 12SJ7 or the 12BE6 and 12BA6 would draw a total heater current of 300mA, there would be nothing left for the heater of a 12.6V tube rectifier (12Z3, 12X4 etc.) so a silicon diode or 117Z3 (miniature) or 117Z4 (octal) rectifier would be needed. The 117V 40mA heater of either rectifier tube would connect directly across the transformer primary and is insulated from the plate and cathode UNLESS the tube developed a short. The elimination of the 117V rectifier tube and use of a silicon diode and series resistor instead would reduce the risk of loss of transformer isolation due to a rectifier tube short. There are also reasonably-effective means of protecting the rectifier tube against transients (line-to-chassis bypass capacitors of about 0.01uF 600V shunted by 2.2M 1/2W resistors) which are the most frequent cause of breakdown of the insulation between heater and cathode. The particulars will be the builder's choice. The bottom line is that quite a nice Part-15 compliant transmitter could be built around an octal or miniature tube complement using readily-available parts.

file not found error on his page.

I gots an old h-out compactron TV tube that might work.

Originally posted by mbates14
file not found error on his page.

I gots an old h-out compactron TV tube that might work. Again, mike, the tube is too big. The TV sweep tubes are all power tubes designed to produce several watts. In the circuit I discussed, the 6J7 is an RF/IF amp used in old radios. In this design, IIRC, it was fed the audio signal at its grid and used as a resistance-capacitance coupled pentode audio preamp to drive the grid of the 6A8 pentagrid converter tube which was operated as a modulated RF oscillator. Again with these old radio receiver RF/IF amp and converter tubes we're in the range of milliwatts with a signal that can be picked up by an AM radio at a distance of 30-50 feet. Use a sweep tube and I bet you could pick the signal up several blocks away. Again, the FCC would be calling and would probably confiscate a device you spent many hours and some cash to build. Plkate currents in these tubes run 1-2 mA or so at a B+ voltage of 120VDC (tube rectifier) or 160VDC (silicon diode rectifier).

Those sweep tubes could be put to much better use in pairs with output transformers and a preamp stage or two in a nice audio amp. A pair of those sweep tubes in pus-pull would probably push 30 watts RMS or more audio into a speaker for mono. Two pairs with two transformers for stereo.

Some old tube manuals like RCA RC15 or RC17 had a circuit for a Part-15 compliant "wireless" transmitter, IIRC.

I bought one of those AM transmitter kits several years ago from AES that uses a 12SA7. Works pretty good. Using a generous length of wire, it would transmit at least 100 feet. I could be at my neighbor's house, and pick it up from my house.

Ah yes! Fahnstock (sp?) connectors!! Haven't seen those in quite a while. Used to use those on all sorts of home brew projects in the 60's

Anthony

can anybody post any schematics to any of those transmitters?

my divide by 4 solidstate oscillator (1610mhz) died.

I got like a 6au6, and a 12ba6

would those work?

the problem I had with my solid state transmitter, is it would not only sound very very crappy, BUT usually, well normally
the farther you walk away from the antenna/xmitter the statickier the signal gets right? well WRONG with my transmitter

it worked rather wierd. the farther i got from it, the audio would drop. it would never get staticky, the audio would just fade and begin to die.

Ah, i was finally able to get to his site.

But, i have an issue. If you look in the schematic below, What am i supposed to use for a tuning cap/coil? i dont have an AA5

Any ideas on what kind of coil in the schematic I could use? i dont have an AA5. never had one, never will.

i dont have a 12av6, or a 12be6.

I have the 6al5, the 6v filiment version. I also have the 50c5, but im not going to use a 50c5. im going to use maybe a 12ba6 for the output.

any ideas?? please.

i wonder if i can make due with all the tubes i currently have.

I have a: 6CB6A, 12BH7A, 12AT7, 12AU7, 5LJ8, 6CB6a, 3GK5, (emerson triple triode, no number), 11BQ11, 23Z9, GY7A, 6BQ6GA, 12BH7, 6AL5, 6BH7A, 8LT8, 17BF11, 50C5, 14GT8, 12AU6, 12BA6, 12BA6.

these are all the tubes I have on hand.

Can I use any of these to substitude for the ones in the schematic??

hmmm. rather quiet.

PM me your address and I'll gladly send you the 12AV6 and 12BE6, on the house :)

Any other tubes ya need?

i forgot to ask you this in your PM, but about the 35W4, can you use diode substitude? I got some huge rectifier dioes lying around. I used 2 of them to replace those seleniums in my TV.

if i could use a diode in place of that 35W4, How?

How many of them do you need? I have a bunch.

a bunch of what.

oh, BTW Charlie reminded me that I went to far off topic, well, if you would kindly move where it starts into AM transmitter to the DIY forums.

thanks.

Originally posted by mbates14
a bunch of what.

35W4s. Should I toss some in the box?

Now is your golden opportunity to rid me of some overstock :D

Did you happen to already order the capacitors for the verticle section of your set?

yes, ill take one, and no not yet.

I think I mentioned in the PM, that I need to raise some money, and once I do that I am going to replace ALL the caps in the set, like I did my emerson.

justradios.com puts together a kit for you.

(emerson had a shorted filter cap, and boy did it let me know).

well after a LOONG time, im finally getting around to my old silvertone.

Anyway, it was burried in a corner, and after the cleanup im pulling it out.

I finally got the anode cap off (I tried to clean under it, but it wouldnt stop arching)

Anyway, there is this brown liquid all over inside the anode cap. no where else outside. it feels and looks like old electrolyte where someone in the past tried to use it and it blew.

I think that it came from a cap (the vertical cap, could be my problems)

That gooey stuff might be the sillicone anode cap deteriorating.

I've found that HV problems are generally due to dirt, and some sets, no matter how muych you clean them, never really stop arcing anyway. But - wipe down the whole HV section, clean the lead, clean the suction cup, and clean the glass around where it plugs into the tube. Clean clean clean. Then clean again. Arcing along the CRT itself is bad mojo, and arcing through the neck is really bad (old zenith color sets from the 70's did this trick, IIRC). Make sure your ground return is good and solid, and contacting the 'dag coating well. It shouldn't be too hard to make it stop.

Hey, how about a few inside shots of the TV set? :)

Oh yeah - about min RF transmitters - remember that class C amps are much more efficient than calss A or AB or B, thus you don't need really big tubes. To get 100 milliwatts, even a 6C4 is 'overkill' - it can pump out 2.5 watts at 150 Mhz (says RCA's book). Remember to use a power transformer to line isolate anything you build - and oh yeah, be careful in that Silvertone too. I'd get an isolation tranny for it if it's not line isolated...

Hey, you can download a freebie/student version of PSpice, and if you've got time, download the tube models and virtually model your designs before you build a real transmitter....

Hmmm, I can see (but it's overkill designwise):

12AT7 - RF oscillator + 1 buffer stage of amplification.
12AT7 - AF amplifer (buffer, really), then modulator/output section (think cathode provides the RF or AF, grid provides the other signal)
100V + 6V transformer, solid PS.

Back on topic :)

When you've got a heat realted problem - you'll find more often than not that it's a capacitor, particularly the wax or 'black beauty' types. Find all of those in your vert section, and hit each one in turn with the freeze spray. But, you'll probbably just want to replace ALL of those paper caps, anyway.

I see my problem.

the 100uf linerity cap in the vertical section had blown up at one time, well thats my vert problem.

Ill replace that, and it should work.