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

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

Philco 19B Shadow meter
#1

Ive finally got this radio working after replacing the 1st IF transformer. Im looking at the shadow meter and Im not sure what I am seeing. This is my first attempt at one of these.
It looks to me that the vane stays centered all the time and doesnt move at all when tuning. It is very free to move when probed and it quickly returns to center when released (magnet ok).
http://www.philcoradio.com/tech/images/19v1.jpg
From what I understand, this is an early version and the circuit does not use a shunt resistor. If I understand correctly, with no shunt resistor in the circuit, the radio would not work if the shadow meter coil was open.
If that is true, Im thinking that the coil is ok.
So any ideas as to why isnt it working??
#2

Could be the magnet. Measure the coil just to make sure it is not open. Then read Chuck's page that has the article about the shadographs, and I think there is something about how to magnetize the magnet again.
Or maybe it was someone else who described the magnet procedure. Just do the search.
#3

Hunter your correct in that the schematic posted does not have the shunt resistor across the shadow meter. If the meter coil is open, you will lack plate voltage on two of the tubes in the front end of the radio. If the radio is working that coil must be good. Good movement is dependent on a strong signal in the front end of the radio.
Jerry

PS: Seems like someone tested meters out of circuit with perhaps a 1 1/2 volt battery to observe deflection. Perhaps someone can comment on that.

A friend in need is a pest!  Bill Slee ca 1970.
#4

Just put a prescribed current through whatever way. A higher voltage will require a resistor. I do not remember off the top what current it is and what the coil resistance is, but those are listed and then it is simple I=U/R thing.




Users browsing this thread:
[-]
Recent Posts
My Philco 37-116 Restore
Are you measuring relative to the centertap or the GND?morzh — 11:57 PM
Philco 610B oscillator wiring
Still not clear on the wiring interface between the 6A7 and oscillator. After refering to the available schematics and s...Tubester — 07:18 PM
Refinishing Ideas
My 37-116 code 121 is the best sounding radio i have...a daily driver. Since we are talking about "changes". ...poulsbobill — 07:18 PM
My Philco 37-116 Restore
Hello, I finally got brave enough to take the cans off the Expander Unit. Got the grid cap wires replaced and back toget...dconant — 06:50 PM
Zenith H725
I got into the first AM IF can today, and found its mica was cracked. Amazing that it was still working. This one makes ...EdHolland — 06:10 PM
Philco model #20
AHH HA , I got it and can’t thank you fellows enough , when I changed the capacitors I took the advice and did not unsol...onlyrick — 02:24 PM
Zenith H725
Hello Ed, yes, I like letting projects run for few days to make sure they don't start acting up . Sincerely Richardradiorich — 01:03 PM
Philco 46-480 Electronic Restoration
I am almost finished with this restoration. All which remains is the power transformer. I cleaned it up some time ago, b...jrblasde — 12:41 PM
Philco model #20
I seem to recall in some TRF sets there being a Local/Distance toggle switch that removes the B+ from the first 24 rf tu...RodB — 09:46 AM
Refinishing Ideas
Hi Doppelganger, After rereading your thread, did you mount the Zenith speakers in the two bottom left and right pos...MrFixr55 — 09:39 AM

[-]
Who's Online
There are currently no members online.

>