#16
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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.
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Bryan |
#17
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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.
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Jeff, WB8NHV Collecting, restoring and enjoying vintage Zenith radios since 2002 Zenith. Gone, but not forgotten. |
#18
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Quote:
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#19
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LOL, yeah, big-band music sounds best on 45 mHz.
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I have one of those around here, somewhere |
#20
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hey bgadow, got any pics of your sets please?
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1977 Zenith Chromacolor II A Very Modern Zenith |
Audiokarma |
#21
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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 |
#22
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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.
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1977 Zenith Chromacolor II A Very Modern Zenith Last edited by vintagecollect; 08-13-2011 at 07:22 AM. |
#23
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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.
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1977 Zenith Chromacolor II A Very Modern Zenith |
#24
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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 |
#25
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Film@Eleven Cliff |
Audiokarma |
#26
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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. |
#27
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Perhaps those sets were meant to tune the TV FM sound carier.
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#28
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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.
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Sean - WØKPX |
#29
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Why channelize radio?
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#30
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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 |
Audiokarma |
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