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  Some have the usual PM type and others use a magnetic type that was outdated over a decade before the 41-42 series.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
Philco 91 Speaker Replacement
The spider is glued on the cone and so is the voice coil. I think you can use a cotton swab dipped in acetone and carefu...RodB — 02:42 PM
Restoring Philco 37-604C
Yes I saw that. If I knew, I'd probably try to arrange for getting it myself. But I have just got one. Which does not m...morzh — 01:44 PM
Philco 38-2 Automatic Tuning
When you push the lever, you are supposed to rotate the disk to the desired station. Then the magnetic tuning will acqu...morzh — 01:42 PM
Philco 38-2 Automatic Tuning
I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push...dconant — 12:11 PM
Philco 91 Speaker Replacement
How would I go about removing the spider from the cone?dconant — 12:04 PM
Philco 38-2 Automatic Tuning
Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to...dconant — 10:51 AM
Does anyone make photofinish replacements?
Here’s the link to the DIY photofinish section of our site: klondike98 — 09:46 AM
Delco car radio Peko vibrator converstion issues
Hi Richard, Thx for posting the schematic.  As I remember as a kid, these were great performers for the time, likely...MrFixr55 — 08:56 AM
Delco car radio Peko vibrator converstion issues
hello mr Fixr, The Electro  Powersupply that I am powering the radio with has a huge choke plus a 10,000ufd electrolyti...radiorich — 10:58 PM
Delco car radio Peko vibrator converstion issues
How about putting a choke in the power supply? The big cap was likely an attempt to stabilize the DC. Kids who cre...MrFixr55 — 09:19 PM

[-]
Who's Online
There are currently 2951 online users. [Complete List]
» 2 Member(s) | 2949 Guest(s)
AvatarAvatar

>