Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Antique Radio

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #16  
Old 07-28-2011, 11:04 PM
bgadow's Avatar
bgadow bgadow is offline
VideoKarma Member
 
Join Date: Oct 2003
Location: Federalsburg, MD
Posts: 5,814
I own a pair of the prewar Philco sets (a table model and a console) but have not tackled either as of yet. I also have a Stromberg-Carlson which is waiting in line.
__________________
Bryan
Reply With Quote
  #17  
Old 07-29-2011, 01:33 PM
Jeffhs's Avatar
Jeffhs Jeffhs is offline
<----Zenith C845
 
Join Date: Feb 2003
Location: Fairport Harbor, Ohio (near Lake Erie)
Posts: 4,035
Quote:
Originally Posted by bob91343 View Post
The nice thing about prewar FM is the good music on there. No rock, no folk.
I don't know how you are getting 1930s-era FM stations on a converted console/table set from that period, unless you have a low-power AM transmitter fed by an iPod, etc. and you're receiving the output from it on an AM frequency on your old set. That or else you're joking.
__________________
Jeff, WB8NHV

Collecting, restoring and enjoying vintage Zenith radios since 2002

Zenith. Gone, but not forgotten.
Reply With Quote
  #18  
Old 07-29-2011, 04:17 PM
bob91343 bob91343 is offline
VideoKarma Member
 
Join Date: Nov 2010
Posts: 745
Quote:
Originally Posted by Jeffhs View Post
I don't know how you are getting 1930s-era FM stations on a converted console/table set from that period, unless you have a low-power AM transmitter fed by an iPod, etc. and you're receiving the output from it on an AM frequency on your old set. That or else you're joking.
You got it. Just a joke.
Reply With Quote
  #19  
Old 07-29-2011, 04:49 PM
radiodayz's Avatar
radiodayz radiodayz is offline
radiodayz
 
Join Date: May 2010
Location: Seattle WA USA
Posts: 120
Quote:
Originally Posted by bob91343 View Post
The nice thing about prewar FM is the good music on there. No rock, no folk.
LOL, yeah, big-band music sounds best on 45 mHz.
__________________
I have one of those around here, somewhere
Reply With Quote
  #20  
Old 07-29-2011, 11:30 PM
vintagecollect's Avatar
vintagecollect vintagecollect is offline
VideoKarma Member
 
Join Date: Jul 2005
Posts: 658
hey bgadow, got any pics of your sets please?

__________________
1977 Zenith Chromacolor II
A Very Modern Zenith
Reply With Quote
Audiokarma
  #21  
Old 07-30-2011, 10:30 AM
tubesrule's Avatar
tubesrule tubesrule is offline
VideoKarma Member
 
Join Date: Jul 2004
Location: Michigan
Posts: 321
My 1939 GE HM-80 has the earlier FM band, 39.5-45MHz, and I am able to receive a few strong local FM stations. I suspect this is due to the harmonics in the LO. Because of this I have never got around to making a converter for this set. I also have a pair of Meissner's, a 9-1047 pre-war and a matching 8C post-war. I used to have quite a few more as I collected pre-war FM's at one time, but this is all I have left.

I do have a converter that is shown on the FM Only site here: http://www.somerset.net/arm/fm_only_converters.html
It's down the page a little under the Crystal Devices heading. It is completely passive. I haven't gotten around to trying it either so I don't know if it works, or how well it works.

Darryl
Attached Images
File Type: jpg P6030262.jpg (85.0 KB, 29 views)
__________________
Converters for obsolete standards:
www.tech-retro.com
Reply With Quote
  #22  
Old 08-08-2011, 03:42 PM
vintagecollect's Avatar
vintagecollect vintagecollect is offline
VideoKarma Member
 
Join Date: Jul 2005
Posts: 658
project is complete! 1941 Prewar FM

I got my Brewster B-10 to pick up two stations finally, one well.

If someone is going to try TV tuner hack, make sure to have a tuner w/ knobs to know what channel tuner is on. A solid state tuner will work better as I pulled a tuner from a junk portable color tv unit as ---low voltage only needed to power tuner as this is an active setup. An ac adapter at 12 volts dc was perfect. The IF output from vhf tuner goes to FM set's antenna connections. The original VHF antenna flat wires should be saved intact from TV set w/ terminals, this is your new FM antenna connection.

I had an old rca to pin connector adaptor I forgot for my 1930 zenith set which was perfect for audio in. Good volume is achieved. I probaly could get more stations but pick up a 93.7 jazz station on the second harmonic is good enough for me now. I'm just happy on making this functional 1941 FM!

TV tuner actually works on TV ch#4, may have to adjust prewar set as well, TV tuner location touchy, strong stations help and good antenna on VHF terminals.
Attached Images
File Type: jpg S3010372.jpg (90.2 KB, 31 views)
__________________
1977 Zenith Chromacolor II
A Very Modern Zenith

Last edited by vintagecollect; 08-13-2011 at 07:22 AM.
Reply With Quote
  #23  
Old 08-13-2011, 07:19 AM
vintagecollect's Avatar
vintagecollect vintagecollect is offline
VideoKarma Member
 
Join Date: Jul 2005
Posts: 658
I have recently been able to pick several stations with a complex combination of tv tuner and dial settings. This setup isn't real feasible unless doing a radio log. It's great to see set pick up several stations. I'm now motivated to make the other converter for better results to cover more of the FM band. There's two versions of the converter shown, a breadboard and a finished point to point solder on a chassis, I guess the later for better selectivity and sensitivity.

If someone tries tv tuner hack, I found moving the FM antenna now to one of tv tuners terminals on top gives best sensitivity. This helped afer changing the delicate shielded cable for IF output of TV tuner to sturdier two wire setup. This caused Brewster tuner to be detuned and tune at new location at 50.5 still receiving well.

Someone needs patience with tv tuner setup, antenna lead position and location, along w/ TV tuner has effect. When changing something as above could detune circuits a little as higher freqs.
__________________
1977 Zenith Chromacolor II
A Very Modern Zenith
Reply With Quote
  #24  
Old 08-13-2011, 11:48 AM
Penthode's Avatar
Penthode Penthode is offline
VideoKarma Member
 
Join Date: Jun 2009
Location: Kitchener/Waterloo Ontario Canada
Posts: 1,059
Quote:
Originally Posted by vintagecollect View Post
Hey pentode, please post a pic of your 1025M PLEASE

thanks for tip pentode. What channel covers the other end of fm dial, channel 7?
Here is my Stromberg Carlson set. It appears that Stromberg Carlson and GE were the first manufacturers to go ito FM in a big way. Stromberg Carlson launched an FM receiver in 1939, one year before FCC FM commercialization.

With the TV tuner set to channel 6 and the local oscillator adjusted upward, The radio will receive 88 MHz to 96 MHz corresponding to 50 MHz to 42 MHz on the old band. Note I reversed the old band from 50 to 42. This is because the TV tuner oscillator is set to 138 MHz. This is how it is calculated:

Channel 6 local oscillator = 87.25 MHz(ch6 snd) + 41.25 MHz (TV snd I.F.) = 128.5 MHz

Low Band FM converter osc. = 88MHz (new band low end) + 50MHz (old band high end) = 138 MHz

Further: Converter osc. = 96MHz (new band 88 + (50-42)) + 42 MHz (old band low end) = 138 MHz.

What this means is that with the local oscillator in the tuner adjusted 9.5 MHz higher to 138 MHz, the old band FM radio will receive the low end of the new band. It must be noted that the old band was 8MHz wide and the new band is 20 MHz wide, so that only a portion of the band is covered with one TV tuner channel setting. It follows that if you can rebuild the tuner to cover the entire band with three separate channel selections of the tuner, each with a progressively higher local oscillator setting. Eg 138 MHz osc. for 96 to 88 MHz, 146 MHz for 104 to 96MHz and 154 MHz for 112 to 104 MHz. Or else you can over lap. Then again you may be able to get the fine tuning control of the tuner give you extra range.

Note that I have also adjusted the TV tuner RF stages for the FM radio band. In that way you can receive more distant stations. I find with the TV tuner, the old Stromberg Carlson can receive distant stations as well as a new FM radio.

Note the inverted calibration. This is because when the local oscillator freq. is set above the incoming signal freq. the RF frquencies are inverted. Recall with analog TV, the broadcast video carrier frequency is lower than the broadcast Sound carrier frequency. The higher local oscillator inverts the arrangement in the video IF.

I hope this helps.

Cheers,

Terry
Attached Images
File Type: jpg SC1025Mb.jpg (91.2 KB, 32 views)
Reply With Quote
  #25  
Old 08-27-2011, 01:18 AM
cbenham's Avatar
cbenham cbenham is offline
VideoKarma Member
 
Join Date: May 2006
Posts: 471
Quote:
Originally Posted by tubesrule;
I do have a converter that is shown on the FM Only site here: [url
http://www.somerset.net/arm/fm_only_converters.html[/url]
It's down the page a little under the Crystal Devices heading. It is completely passive. I haven't gotten around to trying it either so I don't know if it works, or how well it works. Darryl
The "Converters from Magazine Articles" section of this link includes a 1 tube [6J5] and a 1N34 crystal diode converter by Harvey Keys I want to build for my Dad's Philco Console from 1940. It appears simple and the article has good instructions.
Film@Eleven

Cliff
Reply With Quote
Audiokarma
  #26  
Old 09-26-2011, 02:27 PM
DavGoodlin's Avatar
DavGoodlin DavGoodlin is offline
Motorola Minion
 
Join Date: Aug 2011
Location: near Strasburg PA
Posts: 3,400
Mystery FM bands

I will start a new thread but I do not understand the TWO bands these 1947 sets have. I know one is 42-50 MC, but with channel numbers instead.
The Stromberg Carlson 1210-PL is the pretty one. The other one I only have the chassis, stamped "model 1121" and cannot ID. Any ideas?
Dave 63

Last edited by DavGoodlin; 12-07-2012 at 12:41 PM.
Reply With Quote
  #27  
Old 09-26-2011, 03:33 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Perhaps those sets were meant to tune the TV FM sound carier.
Reply With Quote
  #28  
Old 09-26-2011, 03:41 PM
sean's Avatar
sean sean is offline
VideoKarma Member
 
Join Date: Feb 2004
Location: Sullivan, MO
Posts: 257
The 200 to 300 is the current 88 to 108 FM band. Those were the assigned channel numbers (which are still assigned to stations). I have a Meissner FM tuner that has both the frequency and the channel numbers for the modern band.
__________________
Sean - WØKPX
Reply With Quote
  #29  
Old 09-26-2011, 03:44 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Why channelize radio?
Reply With Quote
  #30  
Old 09-28-2011, 03:35 PM
DavGoodlin's Avatar
DavGoodlin DavGoodlin is offline
Motorola Minion
 
Join Date: Aug 2011
Location: near Strasburg PA
Posts: 3,400
Does that mean these had both old and new FM bands? I had the StrombergCarlson for 32 years. I had it working then and it did get a few FM stations on the 200-300 band as I recall. I left the tuner at 102.5 FM as photo shows. BTW, I had an early mobile receiver that did receive a nearby TV's leaky sound carrier on 41.25 MC.

Thanks!
Dave 63
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:57 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.