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

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

box style shadow meter and magnetism woes
#9

>I didn’t do the ones in the tone control…

Your output transformer and the 80 tube is going to hate you when any of them short.

306v seems reasonable.

The meter movement is dependent on the plate current level on the mixer and two IF amps. The more current the wider the shadow. This is because the plate current is controlled by the AVC voltage. It's the dc voltage found on the left side of #26. If you follow it you find it goes to the control grid of the the previously mention tubes. The more negative voltage on the grid is less current/the more positive the more plate current. Also the level of signal at the ant determines it. It takes a strong enough signal to make the meter get a narrow line at it's center.

Something else that determines AVC voltage is the diode section of the 75 tube.

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


Messages In This Thread
RE: box style shadow meter and magnetism woes - by Radioroslyn - 04-28-2023, 04:44 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Model 70 Cabinet Trim
musar , Well if you have any more questions feel free to post away . Sincerely Richardradiorich — 08:56 PM
Model 70 Cabinet Trim
Although I have not made any cabinets or cabinet parts for a couple of years, I still have some parts left over, includi...Steve Davis — 06:26 PM
philcorepairbench.com - shadow-meter
Thanks Ron.fenbach — 02:43 PM
Model 70 Cabinet Trim
Thank you, Gary. Before making my original post, I had clicked on "Steve Davis Cabinets" only to find that it...musar — 02:25 PM
philco predicta
Welcome to the Phorum, cgl18! I am not your resource for television repair, but lots of friendly help is available here...GarySP — 02:12 PM
Model 70 Cabinet Trim
Welcome to the Phorum, musar! You can send Steve Davis a private message (PM). The site is at the top of the Home page...GarySP — 02:09 PM
Model 70 Cabinet Trim
How do I contact him? The only contact information for him I could find when searching online was a telephone number th...musar — 10:38 AM
philco predicta
Hello, good afternoon, I would like to ask what the possible problem could be if I don't have an image on the screen. I ...cgl18 — 10:19 AM
Philco model 38 code 121 not receiving signal.
So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM
462ron
It’s on the bottom of the homepage of our Philcoradio.com homepage! Ron462ron — 07:20 AM

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

>