montgomery: Airline 62-376 Montgomery Wards 6 volt farm radio

ID: 376085
This article refers to the model: 62-376 (Montgomery Ward & Co. (Wards, Airline); Chicago, IL)

? montgomery: Airline 62-376 Montgomery Wards 6 volt farm radio 
05.Apr.15 21:32
19
Arnie Anderson (USA)
Articles: 3
Count of Thanks: 8
I have done several simple radio restorations and have little knowledge about circuitry. I picked up the referenced 6 volt Monkey Wards circa 1936 farm radio radio recently and am completely stumped about the Rider schematic as shown. I have read a bit about the farm radios and how they use vibrators to simulate AC current so that a transformer can be used to adjust the voltage. I have also read a number of articles about building a battery eliminator to bypass the vibrator and power the radio. So here are my questions:
-1- The schematic doesn't give voltages on the tube pins, but I assume all the "A" heater voltage on the tubes is 6 volts; however when it comes to the "B" voltage I am lost. It appears that the oscillator and IF amp tubes use 90 volts, but can't figure out the other three tubes. I also see 135 and 145 volt power in places. 
-2- Will it be possible to build a battery eliminator for this radio? If so I obviously need help so any suggestions will be appreciated.
-3- The other thing that confuses me is that I don't see a rectifier anywhere? Is this because the vibrator only creates a pseudo AC power that can be processed by the transformer but is still actually DC power?
 

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 2
Airline 62-376 
06.Apr.15 02:46
19 from 2117
David Carroll (USA)
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Hi Arnie,

I will try to answer some of your questions.

This radio only uses 6 Volts for everything.  The B+ is created with the synchonous vibrator so there is no need for a rectifier.  From the schematic it appears that the output of the synchronous vibrator produces 145V DC at C23 and is further filtered at C24 to give you 135V DC .  The 90V is created from this voltage from resistor drop for the oscillator circuit.  It does no appear that the rest of the voltages are given but they are probably somewhere between 90V and 145V.  Look at the tubes specs for the appropriate range.  Here is a description of these type vibrators at this site: radioremembered.org/vpwrsup.htm Go to the section on synchronous vibrators.  If the vibrator is not running, it can be fixed in some cases.  I've repaired some these in the past.  It can be very rewarding when get one of these vibrators to work.  If you can't get the vibrator to work, then you will have to build an inverter for it.

Dave Carroll

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 3
airline 62-376 
06.Apr.15 03:46
22 from 2117
Arnie Anderson (USA)
Articles: 3
Count of Thanks: 3
Thank you David for the information in your posting it is very helpful to me. I will look at the references you have given me so I can hopefully proceed with the restoration.

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