[doctormap]

Hi!
I am brand new to the Phorum.  I got a real nice Philco 37-620 at a flea market and I really want to get it working again.  I don't know much about electronics, although I do know the real basic stuff.  I bought new tubes for the slots that were empty, and I got new capacitors to replace the old paper ones.  I just got a new pencil type soldering iron just before we left for vacation (we are up high in the mountains in CO right now).  I have a nice schematic and I have been reading the posts on the Phorum that seem to be relevant to my radio.
Questions:
1.  Does it need an external antenna for short wave?
2.  One of the tube slots was covered up with an old piece of masking tape, which I removed.  It is the middle one on the left side of the chassis, looking at it from the back.  Doesn't it need that tube?
3.  On the top of the chassis, it has electrolytic capacitors in metal cans.  How do I replace the capacitors inside?
Thanks!
I'm sure I will think of  more questions after I start replacing capacitors.

[sam]

welcome doc
replace all caps ,electrolytic`s and cord
you will have to look at schematic and trace wires to make sure you don`t short out some thing where tape is when you install tube
sam

[jerryhawthorne]

Doc, always nice to post a link to your schematic so others can have a quick reference to what your working on.  A rather complex radio if this is your first.  Welcome,  a lot of help here to get it working well.  Schematic link attached. Yes, it will need an external antenna for good short wave reception. As for the caps inside the metal cans they would be the first to replace before ever trying to power up the radio. In general, a good "health check" on the radio should be a priority, specifically resistance checks on the output transformer and field coil. Also the power transformer with the rectifier pulled to measure filament voltages and HV measurements. Nice to have these confirmed as good prior to proceeding. Many threads outlining how to proceed. Those electrolytic caps in metal cans can be handled in a couple of ways. One if there is room underneath the radio is to attach a new terminal strip and cut the wires off the bottom of the cans and set up the terminal strip with the new caps on it. The second is to put new caps inside the metal can (restuff) a little more challenging but leaves the underside of the radio looking original. There are numerous threads on how to do this as well. Look at the attached schematic and determine what tube was taped over. If the socket is there, there was a tube. Could be the rectifier (tube) was replaced with a couple small diodes for some reason.
Best,  Jerry

http://www.nostalgiaair.org/PagesByModel...013212.pdf

As a PS, I strongly recommend going to this site and ordering the proper readable and complete set of schematics for your radio. I never start a Philco project without contacting Chuck and getting complete information on the model.

http://www.philcorepairbench.com/schematics.htm

[morzh]

Doc

there are topics here about restuffing caps.

More than one.

Mike.

[doctormap]

I know this sounds like a stupid question, but the tubes I bought don't have the "G" at the end of the designation (i.e. 6K7G, etc.).  It wasn't until later that I realized that might be important.

Is that a killer?  Do I need to purchase the "G" tubes, or are the ones I bought going to work okay?

[mikethedruid]

The G just refers to the outer form of the tube. A G tube has a glass envelope, tubes without the G are usually the metal outside kind. These will usually work fine. Problems can come from the wires going to grid caps, because the metal tubes are often shorter in height than the G suffix tubes. This can cause the wire to not reach the grid cap if the tube shield is left in place. Metal tubes do not really need the tube shield, so if this is a problem, just put it aside and save it for when you can get a G tube. The metal tube should be OK for testing and use, but SAVE THE SHIELD. One can have a similar, or worse problem using GT tubes which ARE glass envelope, and need a shield, but are smaller in form factor than the G tube... in that case one lengthens, or replaces with a longer wire, the grid cap wire. This trick can also work so you can use the shield around metal tubes, but be careful routing the wire, lengthening it can make it more susceptable to feedback and such.

[jerryhawthorne]

Mike is correct on size and possible grid cap wire routing if the tube has one. There is another concern and that is pin 1 on the metal tubes is used as a ground pin for the tube's metal jacket to provide shielding. It is not used on glass tubes as if they need to be shielded there will be an external shield that connects to the chassis. In this configuration pin 1 on the socket is not needed. The potential problem is that in some cases manufactures use pin 1 on the socket (if they use glass tubes) as a tie point for other wiring. OK, they are cheap but it was free and available on the tube socket. In order to have interchangeability between the two types of tubes, pin one on the socket needs to go to chassis ground as otherwise the tube shield is not grounded. If not used, you need to add a ground wire. If used for something else for a tie point, well I would go with "G" tubes. I like them as they add to the glow of a radio working. Plugging a metal tube in there when it is used as a tie point on socket pin 1 will allow no shielding on the tube and put what ever voltage was applied to pin one as a connection point on the metal surrounding the tube itself. If it was used as a tie point for something with high voltage that tube could give you a jolt if you try removing it or touching it with power on.
Hope this makes sense.
Best, Jerry

[doctormap]

Thanks so much for your kind and gentle replies, I do appreciate it.  As I mentioned before, my knowledge of electronics is rudimentary.  But I do understand the basics of your replies.  So, as long as the ground wires for the grid can reach the ground pin on top of the metal tube, I should be okay.  The one tube I still have to purchase has a shorter ground wire, so I will plan to purchase a glass (G) tube for that one.  I agree, I like the glow from the tubes when the set is on, and I will plan to get glass tubes in the future if needed.

[mikethedruid]

You're welcome doctormap, but you are still not understanding what is what on the tube. The cap on the top of the tube usually goes to a grid, most often the control grid, of the tube. Look at a schematic of such a tube, and you will see the cap drawn like a little square on the outside of the circle, and sometimes even labeled "cap".

If you look here http://www.r-type.org/pdfs/6k7.pdf you will find a data sheet from the 6K7 tube. There at the top you will see a picture of the tube, and a schematic of it's insides. If you notice you will see the little square I mentioned connected to G1, also, note that pin 1 is labeled "S" for shield, because, lacking a suffix, this is a metal type tube. The remainder of the schematic shows each pin, and what it goes to inside the tube.

Hope this helps

[Tom Hamilton]

Hi, and welcome to the forum!

I used phil's old radios to learn some of the basics.  Here is a link:  www.antiqueradio.org .  I would also suggest checking out the videos of Joernone on You Tube.  His videos are geared towards beginners and are very thorough.  He'll take a real mess of a radio and make it into something wonderful.

Tom

[doctormap]

Well, I got most of the old paper capacitors replaced with new ones last week, only burned myself once.  Not too bad.  I will be getting more to replace the "dry electrolytic" capacitors that are in the metal cans on top of the chassis, and one more tube to replace and we should be good to go.  The power cord apparently was replaced fairly recently, as it is a modern vinyl covered cord.  I still have to figure out how to get the short wave antenna attached to the side of the house without contacting anything metal.  I will have to have an insulated wire to go around the window and then some kind of insulated standoffs to hold it under the edge of the roof around the house.  I would like to have about 50 feet of wire, if possible.

[mikethedruid]

Doc, if you wish to safely install an outside "long wire" antenna, really the best for general short wave listening, you will need insulators and a lightning arrestor, as well as a ground stake and insulators for the lead in wires to the lightning arrestor.
https://33.media.tumblr.com/45174faaa39f...1_1280.jpg
I have drawn a diagram of proper longwire installation. The pulley and weight are optional, they provide relief for the wire in high winds.

[mikethedruid]

You can use #14 or #16 stranded wire for the antenna itself. It is best to use bare copper wire for this part, but it can be insulated. The lead in should be insulated, and soldered to the antenna wire. The wire from the lightning arrestor to the ground rod should be #14 insulated also. You can also use a wire from the ground attachment of the lightning arrestor as a ground for the radio if it has a ground terminal.

[jerryhawthorne]

Doctormap, let's not get too far ahead of the project and get the radio working first! Where are you on powering up the radio? Do you have the e-caps installed? Don't try power until such time. When ready let us know and some guidance can be give for a safe testing prior to "blasting off". Play safe!
Jerry

[doctormap]

The power plug is about 12 inches from the wall outlet, which is as close as it will get until I get everything fixed.  I have the electrolytic capacitor replacements and the last tube ordered from antique electronic supply, should arrive later this week.  I plan to just do the new capacitors under the chassis, rather than try to put them in the cans.  Since the new ones are so much smaller, there's a lot more space now under the chassis than there used to be.
By the way, the last time I was soldering capacitors my well-meaning friend went to pick up the speaker and put his finger through the cone.  Can I repair the rip with super glue?  It's about one inch long.