[GreenKeys] Polar Relays

[Jerry Murphy]

A properly adjusted 255A polar relay is very sensitive.  The 255A's replacement,
the 314A, has no adjustments and is also very sensitive.  Attached are testing 
parameters for the two relays.

Jerry Murphy




-----Original Message-----
>From: "w9ddd at tapr.org" <w9ddd at tapr.org>
>Sent: Apr 4, 2021 1:54 PM
>To: Tom Hunter <n3crk at hotmail.com>
>Cc: "greenkeys at mailman.qth.net" <greenkeys at mailman.qth.net>
>Subject: Re: [GreenKeys] Polar Relays
>
>While on this topic, I've been wondering .... Typically one see these used with 10 ma on the bias winding and 20 on the signal winding.  I'm wondering how little current it needed for reliable operation.  Could one use a 10/5 ma combination and still get reliable operation at 60, 75 or 100 wpm?
>
>John, W9DDD
>
>
>> On Apr 4, 2021, at 3:02 PM, Tom Hunter <n3crk at hotmail.com> wrote:
>> 
>> Actually I believe the work is "bistable" meaning it is stable in either of two positions.
>> 
>> I am attaching a picture of the contacts of a 255A. Click on the thumbnail to get the full size photo. This relay is out of adjustment.
>> 
>> I have a  14 MB pdf the adjustment procedure from the 1971 edition of "The New RTTY Handbook" by Byron Kretzman. But it seems too big to attach.
>> 
>> 
>> Tom   N3CRK

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