[Premium-Rx] Eddystone 880-2 information needed

[John Graham 02]

Hi Brooke,

Thanks; the calibrator mod may well work, but it's been very messily 
executed and looks horrible, so I shall be tidying it up anyway.
While I'm doing that I may as well try to restore it to something resembling 
what the manufacturer intended . . . . . . if I can find out what that was 
supposed to be (the "injection probe" might well mean a wire in close 
proximity to the valve).

I may not have made it clear that the contradictory descriptions are _in the 
same manual_ and were repeated in each new edition.

thanks,

John
--------------------------------------------------
From: "Brooke Clarke" <brooke at pacific.net>
Sent: Friday, February 05, 2021 5:54 PM
To: <premium-rx at mailman.qth.net>
Subject: Re: [Premium-Rx] Eddystone 880/2 information needed

> Hi John:
>
> I don't know anything about this specific radio.  It may be that the 
> oscillator frequency gets pulled more the tighter the coupling.  So, over 
> time there may be different coupling methods.  Some official and some done 
> in the field.  It may be that the wire around the tube works well.  YMMV.
>
> -- 
> Have Fun,
>
> Brooke Clarke
> https://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> axioms:
> 1. The extent to which you can fix or improve something will be limited by 
> how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
>
> -------- Original Message --------
>> Hello,
>>
>> Is there anyone with an Eddystone 880/2 High Stability Receiver who can 
>> confirm how the calibrator circuit output is supposed to be connected?
>>
>> The three versions of the manual that I've found online all give two 
>> contradictory descriptions:
>> 1) the text states that the calibration signal is connected via a 3pF 
>> coupling capacitor to the anode of V1B
>> 3) the annotation of the circuit diagram shows the calibration signal 
>> going to an "injection probe to anode of V2" (what exactly is this 
>> "injection probe"?).
>>
>> My newly-acquired receiver does not correspond to either of those; 
>> instead, the calibration signal has been coupled to V3 with a wire wound 
>> round the valve (This does not look original!)
>>
>> I'd like to know how the calibration signal is connected in real, 
>> unmodified, receivers.
>>
>> thanks,
>>
>> John Graham
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>
>
>