[Radioroslyn]

Lately I've been getting some older projects fixed up a 21B chassis, a 70B early model chassis, and a 90 2nd version. The 70 went well just need a few resistors and the speaker overhaul (along with the all the caps, cloth cord, and such). The 90 was a little bit a a different animal. Someone had been in it before and did some iffy work. They did add a fuse and series resistor in the ac line circuit. Also replaced the line bypass caps but use .03 mf which is kinda big. Solder in a couple 10 mf filter caps. All the other caps were original. No I didn't try it to see if it would play.

Started restuffing the blocks and measuring the resistor. Found that there was more bad ones than good. Not a problem I got a lot of resistor. It's kinda fun taking out the bad and put in the good. Know that you've got a good chance that it's good to work when you get done. I get over the the block that is in parallel with filter choke. Check the resistance of the choke and Surprise! It's open. That's what happens when you don't replace the caps in the blocks and you keep playing the set! Fortunately I had a 370 parts chassis that yielded a proper choke. The line bypass block was broken so I needed to find a replacement. This one terminals face differently from most of the ones I had. I was able to take one spin one of the terminals around to match the original.

Next comes the speaker. Opt and fc check ok so it's just a matter of a good clean, recone, and a cord. On the early K speaker I haven't seen cones that were worth trying to save. either the paper the very fragile it just falls apart. Or it's wrinkled which can pull the vc off center ymmv. Soldered on a new cloth cover cord and ready to power it up.

Powered it up and nothing exciting happened. Went around and checked for hv on screen grids and plates of the tube. Found that there was no plate voltage on the rf amp. Rewound primary and secondary. If you are curious the the grid winding is 162t of probably 30g and is 296mH on my cheap meter and 7 ohms. The plate winding was open so I can't tell much about it. It's 96t and probably is about 38g but it's cotton covered. I used 40g cause I had it on hand. It worked fine but it's no picnic to wind on a form, shadow meter no problem. After rewinding this coil the set was working but the audio was low.

After double checking my work several times I found the 47 that I thought I had tested was weak. Found another 47 and that restored the audio level to what it should be. 

I did change a couple of things in the circuit. The tone control seemed awful large in capacitance. By adding all cap together it would make the audio pretty muffled. Even by the 2nd position adding a .015 muffles a fair amount. I chose to use three .005mfd cap. This give the audio a nice bright clean sound till you get to the last position.
The other thing I did was put the filter caps inside #24 (metal tin). Just had to add three wires. No tie strips or caps hang off of the divider resistor. Easy peazy! Actually I did it on all of these set I just worked on.  

After the alignment it's a fine playing set w/good selectivity and sensitivity. Am looking forward to putting some hours in listening to it. And this up coming Spring I'll be working on the cabinets of the above and two 16B's.

[David]

There are no bad Philco Radios some are better than others. Back when the Model 90 was made companys were lucks to stay in business. A time in history with a lot of problems facing folks. Take Care David

[Steve Davis]

The mid is the most common version of the Philco 90. Many will disagree, but I consider it the best. Some like the early version for the push-pull 45 output but it lacks AVC and the P-P output is pretty much a waste when it follows a plate detector and the distortion it causes. The late version has push-pull 47s but they gave up one tuned stage in the front end.

Steve

[morzh]

Agree with Steve, about the Plate Detector. It does not sound well. I have that 90 with 45 P-P, and I wrote exactly that about 10 years ago when I finished it.
A Class A version will sound better if preceded by a Diode detector.
Or the 47 P-P with the same.

[brett2752]

Hello,

I have a model 90 with the 2nd version chassis that uses one 47 as a single ended output. I am looking for a 1st R.F. Transformer. For Philco Model 90 and 90A. Part # 03013. Mine is definitely bad and the inside coil is burnt, the outside coil is fine but I am unable to rewind it. Would you or would you know anyone that would potentially have this piece?

i am new to radio restoration and I would love to get my radio back to work. I have finished the cabinet restoration and its looking great - now its just to get the radio working again.

Thank you

Brett

[Chas]

Hello,I have a model 90 with the 2nd version chassis that uses one 47 as a single ended output. I am looking for a 1st R.F. Transformer. For Philco Model 90 and 90A. Part # 03013. Mine is definitely bad and the inside coil is burnt, the outside coil is fine but I am unable to rewind it. Would you or would you know anyone that would potentially have this piece?  I am new to radio restoration and I would love to get my radio back to work. I have finished the cabinet restoration and its looking great - now its just to get the radio working again.Thank you Brett

Bret, The antenna coil in this radio has an untuned primary ("burnt") and a tuned secondary. Therefore, because the primary is not tuned some liberties can be taken winding a "replacement" coil. the winding is of the "universal" type but scramble winding is fine. It is best to wind the same number of turns and the same wire size. Both are important but for this coil being "off" a bit will not hurt. Scramble configuration is fine. The winding should be in the same direction too.

I, would like to know the configuration of that primary coil. Wire size/type, number of turns, width, and core size. IMHO replication as a replacement part could be practical.

Chas

[RodB]

You may get away with winding the new primary over the top of the secondary. Others can chime in with their opinions.

[tym]

Agree with Chas. As I posted in the OP's other thread, I rewound the RF primary for my 19B and was probably quite a ways off with the turns count - worked fine.