[winkydink]

Hello,

I am new to this forum but a long time fan of tube radios. I own several tube radios (a Zenith Console from 1946, and a 1942 Philco PT94). I have had both electronically restored (recapped) by a professional several years ago.

I am interested in learning how to recap and generally repair these types of radios. I have recently purchased several candidate radios, all from the Philco Family (PT-25, 48-200, 42-PT95, 46-200, 41-221) and would like to know which one would be the best to start with. Some actually work, some are dead, some the tubes glow.

I have a healthy respect for electricity, and the last thing I wish to do is to electrocute myself or catch the house on fire. I am mechanically inclined, but not necessarily electronically inclined (I have had no EE training, but can rewire a light switch etc.). My other main hobby is vintage telephones and have much experience with them, tearing them apart and putting them back together (but alast, they have very low voltages and little electrocution risk).

In any case I have read books on antique radio repair, read various articles on http://www.antiqueradio.org about repair and recapping etc.

I would like some guidance on where to begin, what are some good references, which radio might be a good one to start with, and who are reputable dealers to purchase supplies from. I am not opposed to letting experts handle the radio repairs (and I can tackle the case restoration), but I would like to see if I can safely give it a try.

[imacdaddy757]

Good evening, and welcome to a satisfying hobby. I began in 2005 and am largely self-taught. I did find several references very valuable, and I got some great advice from two antique radio clubs (MAARC and TARPA) in the DC and Virginia Beach regions.

Books: Antique Radio Restoration Guide, by David Johnson.
easy to follow for beginners, plenty to get started with.
Fixing Up Nice Old Radios by Ed Romney. Great tech info, but mostly based on case studies of individual radio. Be sure to highlight key references as you find them--it's not well organized or well indexed, making it tough to find that reference again (like how pins are counted beneath a radio).

Video course: Brett Menassa was selling CDs of his lessons. Electronic repair in some detail, Bakelite, plastic and wood cabinet repair and more. Very recommended.

Remember that the AC/DC sets with no power supply (power transformer) can have a hot 120V chassis, meaning that even a missing knob can be lethal (knob post could be hot). Be careful fixing radios. Even some veterans have been killed.

[dan mauro]

Thanks Winky and Daddy for the encouragement to post a similar letter. I too am a novice at this. I have a Heath shortwave kit I built many years ago, works well, and a Philco 40-180 which works but needs at least an alignment. I haven't read anything on repair, chosing to pick your collective brains instead, since it's much easier to read a paragraph or two rather than a complete book. I understand that electrolytic caps will change over time and may need replacing but when I hear about recapping how do I determine which caps need replacement/refurbishment. Do I test them all first? Can all the caps go bad, even the micas? Do I need to test them under load or just capacitance? Where is the best place for me to start with the 40-180, should I try to realign it first or go through it cap by cap, tube by tube? Thanks for this wonderful forum and a great way to spread the knowledge you all have amassed over many years.
Humbly yours, Dan

[37silverstreak]

Thanks Winky and Daddy for the encouragement to post a similar letter. I too am a novice at this. I have a Heath shortwave kit I built many years ago, works well, and a Philco 40-180 which works but needs at least an alignment. I haven't read anything on repair, chosing to pick your collective brains instead, since it's much easier to read a paragraph or two rather than a complete book. I understand that electrolytic caps will change over time and may need replacing but when I hear about recapping how do I determine which caps need replacement/refurbishment. Do I test them all first? Can all the caps go bad, even the micas? Do I need to test them under load or just capacitance? Where is the best place for me to start with the 40-180, should I try to realign it first or go through it cap by cap, tube by tube? Thanks for this wonderful forum and a great way to spread the knowledge you all have amassed over many years.
Humbly yours, Dan

Hi Dan,
Welcome aboard! This is a great place to get started and there are many guys here that can help you out!
I'll try to answer your question. If you want your 40-180 to work the way it should, you are best off replacing all of the caps save the mica ones. Mica caps usually hold up well over the years and seldom need replacing. however, All the electrolytics and paper tubular caps should be replaced with new units. Also Philco used caps that were sealed with tar into bakelite blocks that were mounted to the chassis. If you have any in your set they should be rebuilt as well. There are detailed instructions on how to do this and it is not hard to do at all!
It's best just to replace them all and not bother with checking them! New caps aren't expensive and you can get a capapcitor kit with an assortment of the most needed values from Just Radio's for like $75 bucks. There is a link to their website on the resources page of the Phorum. I have ordered from them several times and they are great!
Also, you should also check your resistor values as well. They have a tendancy to change over the years and that will also affect how your set operates. I just finished restoring the chassis on my 1931 Philco 90 and I ended up replacing all the resistors in the set as well. After ohming them out some of them were as much as 40% past there original values!! Again, new resistors are available in kit form from Just Radio's.
Do these things first before trying to realign your set. if you try to align it first, any caps or resistors you may need to replace may change the alignment, and you will just have to do it again anyway!
You said that you are a novice at this so I would also like to recommend Bret Menassa's DVD's. I have all 5 of them and he does a great job covering the basics! I bought mine on Ebay.
Hope some of this helps, Good luck!
Kevin

[imacdaddy757]

I agree with Kevin. Start with the Menassa CDs, then the couple of books I suggested. On the caps, yes, replace all but the mica ones. If you do have to test one, one end has to be unhooked from the circuit and you'll need a capacitance tester, available online for not much money. In a few places, you'll replace the large electrolytics with new electrolytics, and those -are- polarity-sensitive. If you put one in backwards it will explode. The film caps you'll use to replace the paper ones are not polarity-sensitive.

Read up on the safety issues before beginning. A mistake can be lethal. The old series (AC/DC sets without a power transformer) are especially hazardous, as its easy to have 110V running through the entire chassis and knob posts. An isolation transformer is a great thing to have if you can find or make one.

I've reworked 35 or so table radios, all AC/DC sets so far. Most of them only required a recap and testing resistors, or changing a couple of resistors, a good cleaning and oiling the tuner variable cap and an alignment. But watch out for flaking wire insulation. Suspect wiring must be replaced or sleeved with spaghetti insulation.

Join a local radio club - it's a good source of information and help, and for such things as tube testers (nice to have your own). The Radio History Society in Bowie, MD is a great resource for diagrams and tubes.

Welcome, and don't hesitate to ask questions. I'm still learning and asking questions.

Clarence

[dan mauro]

Thanks for the great feedback and directions on how to get started. Your advice will be well taken on my next opportunity to look into the 40-180. My wife surprised me with a gift a few weeks ago, a Crosley XJ. It's a four tube, non-regenerative, multi-battery operated set that only has a few dozen components. It was manufactured in the '20s before electricity was standardized in homes and so they were using three or four battery types. I've started collecting information on the set and now have a schematic and a hookup sheet from the factory. This thing is really cool in that it actually has holes in the cabinet so you can see the brightness of the filaments in each tube and adjust them accordingly using a pot knob on the cabinet front as you observe the tube brightness through the holes. Each filament is paralled to one six volt "A" battery. I'm thinking about assembling a multi-voltage power supply for it first thing. I think theres only one trimmer cap for "alignment". I've put this project in front of the 40-180 and any advice anyone can give me on this would be greatly appreciated.

[winkydink]

Thanks for all the good advice. I have an order prepared for justRadios for the capacitors and heat shrink tubing for the ends of the caps.

I have also read the rubber covered wiring article on the Philco forum and realize that the wires will need to be replaced or resleeved. The author says he prefers to resleeve than to replace. What diameter tubing would be needed to resleeve ?

Additionally, I am going to purchase an isolation transformer and variac to do this work. Can anyone give me any suggestions as to type. I am basically going to be working on the ac/dc sets in the 1939 to 1948 range. I don't mind buying used (on ebay) but would like some representative models and/or features that I should have for this type of radio.

Again, thanks for all the helpful advice.

[Dave]

Before bidding for a variac or isolation transformer on eBay, visit some electronics swap meets or amateur radio shows. They turn up very frequently and since they are pretty heavy items, you won't have to pay a fortune on shipping (it's also a good place to find old radios, parts & test equipment). Last year I picked up a massive antique variac for $20 at a local hamfest. Look for one that can handle a current load of at least 2-3 amps, which is plenty for most radios, although radios with high tube counts may require something a bit beefier.
An isolation transformer isn't a requirement for working on radios, but it's a lot safer if you use one. Think of them as an inexpesive insurance policy. Look for one that has a 120 volt output and an adequate current supply. There are a few techniques that you should follow to help prevent leathal shocks which are also a good practice even if you do use an isolation transformer. When working on a live radio, keep one hand behind your back at all times, use tools with well insulated handles, don't wear jewelry or a metal watch and if you must touch the radio, use the back side of your finger (if you do happen to get shocked, your muscles will tense up and pull your finger away rather than latching on & causing more harm).
As for the wire sheathing, most folks prefer to use heat shrink. Use the smallest diameter that will still easily slide over the wire. Replacing the wires is a little more tricky, but it's usually fairly painless if you follow these rules... use the same gauge or slightly larger, cut it to the same length and route it exactly the same as the original. It will help greatly to take lots of photographs from every possible angle before you begin any work. That way you can refer back to them to make sure everything gets put back the way it was.
Dave

[winkydink]

Before bidding for a variac or isolation transformer on eBay, visit some electronics swap meets or amateur radio shows. They turn up very frequently and since they are pretty heavy items, you won't have to pay a fortune on shipping (it's also a good place to find old radios, parts & test equipment). Last year I picked up a massive antique variac for $20 at a local hamfest. Look for one that can handle a current load of at least 2-3 amps, which is plenty for most radios, although radios with high tube counts may require something a bit beefier.

An isolation transformer isn't a requirement for working on radios, but it's a lot safer if you use one. Think of them as an inexpesive insurance policy. Look for one that has a 120 volt output and an adequate current supply.

.....
Dave

Unfortunately I am several hours from the closest major city, so ebay or retail are my two best choices. That is unless someone from the forum has a cache of variac and/or isolation transformers that they wish to sell.

Again, any brands to focus on or avoid ?

One other question, with regard to replacing the power cord for these type of radios (AA5). Should I purchase polarized or non polarized cord/plug. Is either "safer" ? I have read that because the original plugs were non-polarized, when the radio is plugged in one way vs the other that the chassie is more dangerous. Not sure if this is true but perhaps someone can shed some light on this for me.

Thanks.

[imacdaddy757]

WinkyDink, I use "Spaghetti" sleeving for the ends of caps and resistors in most places, heat shrink in a few other places. Spaghetti is available in two sizes from TubesAndMore online. You want their smaller size for most applications, that slides over a 20ga wire.
I'm a safety nut. I'd use a polarized plug, but pay attention when you trace your circuits so you get the larger terminal side of the cord running to the Ground inside the set. If in doubt, ask questions here or at a local radio club. And there is advice online about adding a glass fast-blow fuse to old sets. I wish I'd done so on sets I refurbished earlier, but will be adding a fuse to my sets beginning with the one I'm working on now.
Clarence

[winkydink]

Any idea where I can purchase a polarized plug with a inline fuse ?'


Let's say that I am working on a 48-200 on the following schematic where would the "polarized" lead goto (i.e. where is the ground on the radio)

http://www.nostalgiaair.org/resources/627/M0013627.htm

[winkydink]

Another question with regard to the model 46-200 and model 48-200. Both have a loop antenna glued (I guess) to the inside of the bakelite shell. When I clean the radio shell, should I remove this ? If so how and how do I put it back ?

I am going to assume immersing the shell in water as a first step of cleaning would not be a good idea, with the loop antenna still glued to the shell.

[imacdaddy757]

WinkyDink, I've never immersed a set to clean it. I use brushes, compressed air and windex on a paper towel on Bakelite sets. Sometimes Q-tips to get into little grooves. But I'd not immerse a set that has an antenna or intact label inside. Far as labels, go ahead and cover any that remain with wide clear packing tape to preserve them - it's quite acceptable in restorations. If someone can't ID the set's model number in the future, it's really hard for them to get schematics or service it.
If it were my set, I would not take a glued-in antenna out. Just clean the area as I described above.

Regards,
Clarence

[Bob Andersen]

Any idea where I can purchase a polarized plug with a inline fuse ?'


Let's say that I am working on a 48-200 on the following schematic where would the "polarized" lead goto (i.e. where is the ground on the radio)

http://www.nostalgiaair.org/resources/627/M0013627.htm

The metal chassis is ground, but not connected to either side of the AC line.

I would rewire a set like this slightly so that switch is on the hot side going to pin #1 on the 35Y4 rectifier. Then, the neutral side of the plug goes to the 'B-" buss.

I usually hide a small fuse somewhere under the chassis rather than use one in the power cord.

[codefox1]

Agree with all, but never bet your life that the recepticle on the wall is wired correctly. Even a 3 prong grounding plug can present a hazard with any transformerless set, but you can usually get rid of the grounding capacitor(s) after connecting the ground wire to the chassis on sets with a floating B-. A safety (fail open) capacitor wired after the switch between the neutral and hot wires of the AC line usually gets rid of noise. I also agree that fuse is great idea, and no matter what, I never touch these chassis when power is applied. Never!