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philmore: 500; Philmore Junior Microphone

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Forum » Radios and other type of sets (Physics) etc. » MODELS DISPLAYED » philmore: 500; Philmore Junior Microphone
           
Don Roman
 
 
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22.Jun.09 22:38

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II'm looking for the hook-up instructions for the Philmore Junior Microphone (#500).  This microphone had 

lleads which fit over the vacuum tube pins of various vintage radios.  Thanks for your help.

Joe Sousa
Joe Sousa
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23.Jun.09 22:23

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Hi Don,

The original instructions may never surface, but it may still be possible to figure out how to hook this up, if you sent some extra info:

-Photos, including detail of socket pins. You can attach these if they are more than 590pixels wide.

-DC resistance measurements on pins.

While using an ohm-meter to check pin resistance/continuity, you should notice faint clicks comming from the microphone, that are caused by the ohm-meter test votlage when contact is made.

If the microphone is a crystal type, then the ohmeter should read open circuit, but you should still hear the faint clicks.

If the microphone is dynamic/magnetic, you should measure a DC resistance, no more than a few kOhms. This type of mike usually needs a step-up transformer to drive tube circuits easily, and the transformer would likely be included in the mike assembly or socket.

Regards,

-Joe

Joe Sousa
Joe Sousa
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24.Jun.09 00:37

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Hi Don,
I went looking around and came across Ebay auction 200354321497 by seller "pfschgo", with a Philmore microphone with documentation. I asked Paul, the seller, permission to post his photos here, and he gave permission.

The text is barelly readable in one of the photos, but still provides useful info. Nost noteworthy, is the recommendation that the microphone be wired between the plate and filament of the detector triode, in the first wiring example with the 01A tube. The DC plate voltage of detector triodes is usually not more than 22V.

Ebay auction 310107422332 also has a picture of a Philmore microphone beside it's case and docs.

The mechanical method of connection is via snug fitting lugs that slide over the tube pins, so the mike remains in parallel with the detector output.

Regards,

-Joe


June 24th 2009

Ebay seller quadwranglemusic (Luis) has kindly consented to the posting of his photo from auction 310107422332 for the Philmore 500 Junior microphone.

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This article was edited 25.Jun.09 05:32 by Joe Sousa .

  
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