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

Philco 90 WW resistor question
#3

radioroslyn: I was going over your results and it seemed that a 20 watt resistor would much more than needed, and physical size also.  I attempted to do some calculations to see what I came up with.  Unfortunately, I am working on a chassis that I have not powered up.  The speaker I have has an open field coil, so could not measure resistance, but I found that the DC resistance should be around 3000 ohms.
  
Adding the total tube current from the data sheet, it comes to 42.15ma, not counting the power dissipation of the field coil.  I used your estimate of 45ma for the calculations.  If this is the total current throughout the B+ loop, I came up with much lower power ratings.  Using the current and resistance values, I calculated the voltage drop across each resistor, then calculated wattage.

The 180 ohm = 8.1 volt = .36 watt.  The 60 ohm = 2.7 volt = .122 watt.  The 3500 ohm = 157.5 volt = 7.1 watt.  Based on my calculations, I should be able to use 2 watt resistors for the 180 ohm and 60 ohm resistors and a 10 watt resistor for the 3500 ohm?  Does that sound reasonable?

The other variable is a resistor to replace the field coil, possibly 3000 ohm at 10 watt?

If my calculations are wrong, please let me know.
Thanks,
johnschw    


Messages In This Thread
Philco 90 WW resistor question - by JohnSchw - 05-22-2022, 11:00 AM
RE: Philco 90 WW resistor question - by JohnSchw - 05-25-2022, 12:48 PM



Users browsing this thread: 1 Guest(s)
[-]
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.

>