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

Philco 38-10 Antenna input
#1

While restoring my 38-10,I noticed in my Riders that that when using the factory supplied "All Wave Antenna" (basically a dipole) one side of the antenna is always at chassis ground potential regardless of band switch position (The black lead) .IMHO,this renders half of the antenna useless for reception.Is this a factory goofup or is there a reason for this? 73 de Bill
#2

W4NJF,

It apparently is just like a half-wave ham dipole. The 'active' side is a quarter-wave. The other side is basically serving as a counterpoise.

This arrangement allows for resonance and a low impedance feedpoint. Look at the SO-239 on the back of your ham gear. Its at ground. Icon_smile

Some sets do this arrangement using a balanced feedline and/or balun/xfmr. Not sure if one is any better than the other in this application (broadband).
#3

hI EXRAY,Gotta disagree with you on this one,in the 1937 Philco models that used the same antenna,the primary antenna windings were center tapped to ground and the antenna itself was switched to "T" configuration on the BCB and operated as half wave dipole on SW.The exact resonant frequency of the antenna was dependent on how long you cut each leg-usually about 12 Mhz (25 meters).So why put a dipole for 40 meters in length when one for 20 would do?(for rx purposes only!).I can see your take on the counterpoise,but I'm not talking verticals here.
#4

The bandswitch does the balaned/un-bal switching, I believe.

Chuck
#5

Bill Fulling Wrote:hI EXRAY,Gotta disagree with you on this one,in the 1937 Philco models that used the same antenna,the primary antenna windings were center tapped to ground and the antenna itself was switched to "T" configuration on the BCB and operated as half wave dipole on SW.The exact resonant frequency of the antenna was dependent on how long you cut each leg-usually about 12 Mhz (25 meters).So why put a dipole for 40 meters in length when one for 20 would do?(for rx purposes only!).I can see your take on the counterpoise,but I'm not talking verticals here.

If its a question of length then they were possibly operating the dipole at both 1/2-wave and 3/2-wave lengths. Using a freq 12 Mhz (25 m) just for example...a dipole of 37.5 meters in length will work as well if not a tad better than one of a 12.5 m length PLUS the 37.5 m one has the advantage of working at 4 MHz (75 m wavelength) as well.

I have no idea if thats what they had in mind but a dipole would work that way.

-Bill




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Shadow Meter Bulb
Phorum members, I am trying to find the bulb # for PHILCO Shadow Meter part number 45-2180 that is from a 37-640 chassis...georgetownjohn — 06:53 PM
Philco 41-608 changer coupler
3D-printing...short of machining, of course. Or molding.morzh — 05:20 PM
Philco 41-608 changer coupler
Thanks, Morzh. That solves the issue of the rubber pieces. Now, I need to find a way to replicate the pot metal piec...alangard — 05:07 PM
12' Philco
If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel. Kareem would have an e...morzh — 01:48 PM
12' Philco
And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM
Hickok AC51 tube tester
I think they have only shown the secondaries of the transformer. Two of them feed the rectifiers' filaments.morzh — 12:58 PM
IF can wire size and Rubber mounts?
Arran If the wire inside cans is the gauges you mentioned, the sole reason for that would be mechanical, to stiffen t...morzh — 12:56 PM
12' Philco
Rod, Yes, I know, but the Giant Philco is not around anymore either, so I go by whoever was alive fairly recently. H...morzh — 12:54 PM
Hickok AC51 tube tester
Absolutely no one is going to reverse engineer that circuit. Even the iron core is missing.RodB — 10:37 AM
IF can wire size and Rubber mounts?
Thanks to both members for your help regarding wire and tuner mtg supports. regards--Johngeorgetownjohn — 09:33 AM

[-]
Who's Online
There are currently 5050 online users. [Complete List]
» 2 Member(s) | 5048 Guest(s)
AvatarAvatar

>