[Milsurplus] ARC-2: Smart People Needed

[David Stinson]

----- Original Message ----- 
From: "Ian Wilson" <ianmwilson73 at gmail.com>
To: "David Stinson" <arc5 at ix.netcom.com>
Cc: "Military Surplus net List" <milsurplus at mailman.qth.net>
Sent: Wednesday, April 02, 2014 4:34 PM
Subject: Re: [Milsurplus] ARC-2: Smart People Needed


>I set up a quick simulation, but had to guess at the component 
>values.
>
> Dave - what value are the capacitors across the IF coils 
> (alternatively,
> what
> inductance are the coils)? I am assuming a frequency of 1.25MHz 
> approx.
>
> My simulation says reducing the coupling capacitance makes very 
> little
> difference (since tube plate looks like 500k ra and 7pf output 
> capacitance
> (plus strays)), I wouldn't have expected the coupling cap to 
> make any real
> difference.
>
> The BW did go up fractionally but nothing you'd notice.
>
> This situation usually means that the model doesn't represent 
> the true
> situation. I only modeled one stage (not that that would change 
> anything
> dramatic). So please send component value(s) and I will take 
> another look.
>
> 73, ian K3IMW
>
>
>
>
> On Wed, Apr 2, 2014 at 8:43 AM, David Stinson 
> <arc5 at ix.netcom.com> wrote:
>
>>
>> ----- Original Message ----- From: "Ian Wilson" 
>> <ianmwilson73 at gmail.com>
>>
>>
>>
>>  Are the IFT primaries and secondaries coupled by both 
>> magnetic (proximity)
>>> coupling and capacitive coupling (the 5pF caps) or only by 
>>> the caps?
>>>
>>
>> The schematic shows both windings in a single shield
>> but if you look at the coil rack itself, the primaries and
>> secondaries are completely shielded from one-another
>> in individual metal cans.  The only coupling, unless there
>> is some residual magnetic through the open ends of
>> the shield cans, is through the 5 pFd cap.
>> The later AN/ARC-2A manual shows
>> the correct shielding.   Maybe disconnect the 5 pFds
>> and see if there's enough residual coupling to
>> do the job?
>>
>>
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>