Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Philco 48-200 alignment questions
#1

Hello Philco people!

I have a 48-200 that definitely needs alignment, but before I get the alignment tools out I just want to make sure I'm understanding what the service data is saying. From what I'm reading it's saying for the 455 adjustment to connect the output lead of the signal generator through a .1mfd cap to pin 6 of the 7AB tube and the ground lead to pin 7 of the 14A7, am I reading that correctly? Also can anybody suggest using something other than a .0001 mfd cap for adjusting the high side of the dial? Thanks.
#2

Use an isolation transformer and you could just connect the output of the generator to the ant connection. Set the dial for 550kc. There's enough signal leakage thru the 7A8 that you'll hear it fine. 
As for the adjustments on the tuning cap one is going to set the placement of the stations @ the top end of the dial and the other sets the sensitivity. Both of these you could use local stations the adjust. Or you could use a gimmick cap.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#3

Thanks for the reply Terry.

Yes I am definitely using an isolation transformer. If I work with your method and connect the positive lead to the of the antenna instead of the 7A8 I would also connect the ground lead to the chassis, correct?

As far as the adjustments on the tuning cap, what is the gimmick cap you're reffering to? Thanks!
#4

Yup.

The gimmick is to take the place of the 100mmfd cap you don't have.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#5

Hi, in this case I would be certain that pin 7, which is B-, of the 14A7 is not "hot". If it is then reverse the power plug. This is a hot chassis radio and when you attach the negative side of the generator to B- you don't want sparks. Instead of using the 100pf cap run the generator output hot lead to a loop of wire of several turns about 6 inches dia. Put the loop close to the loop antenna of the radio. Increase or decrease the distance to change the signal strength to the radio.
#6

Terry's gimmick cap is two insulated wires twisted together about 2 inches long, one wire attaches to the generator output and the other to the radio circuit. The wires act as a capacitor.
#7

Thanks to everybody for all the info so far.

RodB, thanks for the additional info. I worked on this radio years ago and put in a new AC cord and a polarized plug. I'm pretty sure I wired it so the hot side goes to the switch, I'll have to check. If that is in fact the case I'm imagining that the 14A7 is not hot and I'm good to connect to pin 7?
#8

Just checked the power cord and I did in fact wire it so the hot side (small prong) goes to the switch.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
The list of my radio & TV collection!
Hello Peter, Thank you for posting that !! Sincerely Richardradiorich — 09:40 AM
Eico 232 VTVM Schematic
It's a microwave antenna. ?;-p?. I substituted 1N4002s off the 6.3 vac winding for the 1.5 volt battery. Uniprobe is the...RodB — 05:50 PM
Eico 232 VTVM Schematic
Try BAMA for a schematic. Looks like a replacement power source for the D battery has been installed. The tube may be...Chas — 04:51 PM
Eico 232 VTVM Schematic
Is that a battery holder?morzh — 04:43 PM
Eico 232 VTVM Schematic
A friend gave me this Eico 232 VTVM and I'm having trouble locating the schematic for it. This one seems to be a later v...RodB — 04:17 PM
Var resistor id
Considering what it is in series with, I doubt there should be any power requirements. Of course, we should know wher...morzh — 03:23 PM
Var resistor id
Trim pot, about 1/2 watt part of focus divider. As stated 2k ohms. This appears to be a rusty chassis, resolder all ...Chas — 03:19 PM
Var resistor id
Its a Sylvania 400 oscilloscope. here is a clip of r-100. Would be nice to know the current required. Not listed in part...Martinj — 02:10 PM
The list of my radio & TV collection!
Thanks Richard. I hope you enjoy it. Here I have created an English section on the history of radio with videos in Engl...RadioSvit — 10:23 AM
The list of my radio & TV collection!
Hello RadioSvit, first all happy new year ! I will watch your new videos this week. Sincerely Richardradiorich — 09:19 AM

[-]
Who's Online
There are currently 5064 online users. [Complete List]
» 1 Member(s) | 5063 Guest(s)
Avatar

>