Posts: 7,220
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Check the vane to see if its stuck. Try blowing on it. It's delicate and breaks easily. Wouldn't hurt to put a small bit of oil on the pivot points. Do this by putting a very small amount of oil on a piece of solid wire (like one on a mylar cap 24g or so). Gently touch to the pivots. It's like your oiling a watch, no drops of oil.
If you have a milliamp meter handy you can measure the current w/the s/m out of the circuit. Should see abt 10ma difference from strong to weak signal.
The bulb alignment will make a big difference in how well you can see the deflection of the vane. The filament of the bulb should be lined up with the slot in the back of the meter. You'll figure it out, it just takes a little bending of the bracket and twisting the lamp socket.
Here's a few pics of the s/m coil apart.
https://philcoradio.com/phorum/showthrea...829&page=3 Go down to post 46 or so. Happy fill in the blanks if you have questions.
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
Posts: 27
Threads: 3
Joined: Apr 2019
City: Miami
State, Province, Country: Florida
The shadow meter that came with the radio has an open coil. The shadow meter I am using now came from a Philco17. The vane on the Philco 17 shadow meter is not stuck. When I turn the radio on the shadow goes from narrow to wide and stays wide all the time even as I tune through all the stations.
(This post was last modified: 02-09-2022, 10:00 PM by
boxjoint.)
Posts: 7,220
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Sorry misunderstood. The older s/m use a permanent magnet to center the vane and has some control over the sensitivity. Later models have a thumbscrew at the back to set the tension on the vane. These tend to be more sensitivity because you can lessen the drag used to center the vane and it can move more freely.
If you still have the resistor across the s/m that will diminish it's movement.
Good tubes, alignment, and a good long ant. It comes down to the avc voltage generated by the signal causing the change in plate current on the mixer and 1st IF amp tubes. If the signal is weak the s/m may not react as the avc has got the gain flat out and the tubes (mixer/ IF) aren't drawing enough current to make much of a difference on the meter.
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
Posts: 27
Threads: 3
Joined: Apr 2019
City: Miami
State, Province, Country: Florida
I am attempting to take apart the shadow meter that came with Philco 16B. I believe this is the early type of shadow meter. I removed the bottom panel to expose the vane inside. It looks like it has a screw that holds the coil on top. I then removed the top panel to expose the coil.
What would be my next step? Do I remove the screw located below the vane which I believe holds the coil on top? Do I remove the screw with a metal flat head screw driver? It seems the vane could easily be damaged by removing the screw.
Once the top coil is removed will I be able to mount it on a battery powered drill and rewind the coil?
-Carlos
Posts: 27
Threads: 3
Joined: Apr 2019
City: Miami
State, Province, Country: Florida
Hey Terry,
I am also very curious on a comment you made on the shadow meter post.
It's been playing for a hour or so picking up my little converter (converts audio to rf signal) which receives it's audio signal from the net.
Can you please tell me what converter you are using to hook up to your radio? I would very much like to get one of these devices.
-Carlos
Posts: 7,220
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Actually I've had a few different ones for one reason or another I haven't been too impressed. The one tube phono osc ('SA7) models level of modulation is low and the osc frequency shifts at an rate (aka FMing). Range usually is not far at all. A foot or so. Hum can be an annoying problem.
Most of the listening I do is on the air. But I do have some plans to build a wireless broadcaster using a couple of 6AW8. It's on a long list of to do projects...
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
Posts: 27
Threads: 3
Joined: Apr 2019
City: Miami
State, Province, Country: Florida
Terry,
Did you get a chance to read my other post? I am trying to fix the shadow meter that belongs to the philco 16b.
-Carlos
Posts: 7,220
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Missed #19.
Bend up the 5 tabs on the bottom and remove the cover. This will get you inside. Unscrew the large black screw while being careful not to damage the vane assembly. Lift out vane assembly near the small screw w/needle nose pliers. Bend up the remaining 6 tabs and remove the top cover. There's the coil and under it is a small bar magnet. It's used to center the vane. Some say that it improves the meters sensitivity if you remagnetize it. I tend to think not. Remove the bobbin from it's bracket and cut the wire off of it. A snap blade or Xacto knife works well.
1/4 bolt and nut can be fitted thru the bobin to mount it to your drill. You'll need some 38 or 40ga magnet wire. The trickiest part is getting use to the feel of the tension that you can put on the wire. If it breaks in the middle not a big deal. Clean the ends and solder it back together. Paint it w/some nail polish and your good. If it breaks at the start point after you've wound a bunch on that's kind of a problem.
In terms of how much wire? I just eye ball it then measure the resistance. It's not all that critical something around 1200-1500 ohms is fine.
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
(This post was last modified: 02-10-2022, 05:09 PM by
Radioroslyn.)
