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

PT 87 speakers
#1

Why did Philco use 2 types of speakers in these portables ?  Some have the usual PM type and others use a magnetic type that was outdated over a decade before the 41-42 series.
#2

You're asking a question that only a dead Philco engineer can answer...and dead men tell no tales.

--
Ron Ramirez
Ferdinand IN
#3

Ron is right, "Dead men tell no tales." I will; however, attempt to give you an answer. The electromagnetic type speakers have an advantage. The field coil can be used as a filter choke in the power supply of the radio, smoothing out the DC, and reducing hum. PM speakers do not have a field coil, and so do not have this advantage. If one wants to provide this inductive smoothing of the DC, one must add a filter choke to the power supply circuit, which takes up space on the chassis, and is another part which costs money. The difference between the cost of an electromagnetic speaker, and a PM speaker in those days was less than the cost of an additional filter choke. So, the choice of using an electromagnetic speaker made sense from both a chassis room and a cost perspective.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Made mistake & did not label connection
Hi John, I don't have this radio, but I can supply some info: Based on your pic, pins 7,8 and 1 are used together, go...MrFixr55 — 02:02 PM
New Philco Repair Bench
As far as I know, the Repairbench does not work, and has not been working in a while. Chuck (we had that campaign looki...morzh — 01:33 PM
Radio city products 664 schematic request
Need a schematic or manual for the 664. The 663 may be similar.daveone23 — 12:38 PM
New Philco Repair Bench
Thanks Gary.dconant — 12:16 PM
New Philco Repair Bench
I tried accessing the site through our library and got the same response. It's reported to our tech gurus. GaryGarySP — 11:50 AM
New Philco Repair Bench
I am sure this is the archive, and not the Chuck's site.morzh — 09:50 PM
Made mistake & did not label connection
It's not like we are good friends with that wire and can tell it from other ptetty identical looking wires. Why'n't you...morzh — 09:49 PM
Made mistake & did not label connection
I'm not sure why that wire wasn't covered in the video. I'm pretty sure the 6A8 won't work until that pin is grounded. Y...RodB — 09:47 PM
Made mistake & did not label connection
You'll have to forgive me, I am not sure what you mean.  Can you explain what you are really saying.  If anyone does not...georgetownjohn — 08:05 PM
Made mistake & did not label connection
Those are details better left to the ones who know. Maybe you disconnected the wrong end of the wire.RodB — 06:22 PM

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

>