1. The PHILCO Phorum
  2. Various and Sundry Categories
  3. Other Radios (Non-Philco)

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

Linear Mode
Sears Volume/Power Control
NV3G
Member
***
Posts: 74
Threads: 42
Joined: May 2008
City: Shinnston, West Virginia State, Province, Country: USA
#1

12-13-2008, 10:17 AM
I am presently working on a Sears Model 1708 radio. It has a dual potentiometer of which 500K is the volume control and 1K is the variable cathode resistor for the RF ( 78 ) tube and the Oscillator/Detector tube ( 6A7 ). I do not understand this type of design. What did the engineer have in mind? How does it work when your increasing the volume control for audio and decreasing the cathode resistance in the cathode circuits of the RF and Oscillator/Detector Stages?

Any help would be greatly appreciated and where do I find a replacement control? Perhaps a modification is in order.

I am confused.

Thank you,
nv3g
Find
« Next Oldest | Next Newest »
Thread Closed


Messages In This Thread
Sears Volume/Power Control - by NV3G - 12-13-2008, 10:17 AM
Re: Sears Volume/Power Control - by Texasrocker - 12-13-2008, 11:05 PM
Sears Volume/Power Control - by NV3G - 12-13-2008, 11:46 PM
Re: Sears Volume/Power Control - by Texasrocker - 12-14-2008, 03:27 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 42-345 Restoration/Repair
Hi OSanders, Look carefully at the band switch. Turn it slowly and "wiggle" it around the desired band. ...MrFixr55 — 12:33 AM
5U4 vs 5Z4 tubes
I think that RCA and GE introduced metal tubes in the USA in 1936.  I don't know if they were being made by RCA, GE or b...MrFixr55 — 11:20 PM
Philco 42-345 Restoration/Repair
Vlad95, Thank you for the stringing guides and wow there are so manyosanders0311 — 06:01 PM
5U4 vs 5Z4 tubes
A pre war Hallicrafters, and an early one too, very nice! 1936 is pretty early for metal tubes too, which would explain ...Arran — 05:58 PM
Philco 42-345 Restoration/Repair
Thanks Rod, "When you hear the background hiss and no station it usually indicates that the oscillator quit" ...osanders0311 — 05:52 PM
Philco 42-345 Restoration/Repair
RodB :beerchug:Vlad95 — 10:22 AM
Philco 42-345 Restoration/Repair
Vlad, you nailed it. Swiss and German roots.RodB — 09:54 AM
5U4 vs 5Z4 tubes
Well this is a Hallicrafters SX/9 circa 1936. No real issues so far although I dodged a real bullet with a cap that was...bridkarl — 07:59 AM
5U4 vs 5Z4 tubes
The pinout is the same but the 5U4 has a 3 amp filament, verses 2 amps or less on the 5Z4. I think that the pinout of a ...Arran — 12:04 AM
Philco 42-345 Restoration/Repair
By the way. osanders0311 Take a look here: Dial cord stringing Guides May be here you can fount correct string settin...Vlad95 — 11:15 PM

[-]
Who's Online
There are currently 1044 online users. [Complete List]
» 1 Member(s) | 1043 Guest(s)
Avatar

>
  1. The PHILCO Phorum
  2. Various and Sundry Categories
  3. Other Radios (Non-Philco)