[AMRadio] GB> Re: Filament choke


crawfish at surfmore.net crawfish at surfmore.net
Fri May 1 20:09:10 EDT 2009


The voltage rating on the load side doesn't have to be as high as on the
tune side, as the impedance is lower. You got all bases covered.
                                                              Joe W4AAB


> I've got a fairly wide-spaced 500 pF air variable for the tuning cap so
> no more should be needed there.
>
> For the loading side, I've gathered some "transmitting" caps of 1000 pF
> each, 5kV to 8 kV rating, to go in parallel with either a 1000 pF
> vacuum variable (with motor drive!) or another one of the 500 pF air
> variables.
>
>
> Steve WD8DAS
>
> sbjohnston at aol.com
> http://www.wd8das.net/
> ---------------------------------------------------------
> Radio is your best entertainment value.
> ---------------------------------------------------------
>
>
> -----Original Message-----
> From: Edward Swynar <gswynar at durham.net>
> To: Discussion of AM Radio in the Amateur Service
> <amradio at mailman.qth.net>; glowbugs at piobaire.mines.uidaho.edu;
> SBJohnston at aol.com
> Cc: amradio at mailman.qth.net
> Sent: Fri, 1 May 2009 12:23 pm
> Subject: Re: [AMRadio] Filament choke
>
>
>
>
>
>
>
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>
>
> Hi Steve,
>
> What kinda fixed padder capacitors are you placing in parallel with that
> plate tuning capacitor, as well as the plate loading cap, in the final
> pi-tank...?
>
> I'm sure you're already well aware of it, but you've gotta be REAL
> PICKY in
> these applications, as I discovered here the hard way...! Hi Hi.
>
> ~73~ Eddy VE3CUI - VE3XZ
>
>
> *************************************
>
> ----- Original Message -----
> From: <sbjohnston at aol.com>
> To: <glowbugs at piobaire.mines.uidaho.edu>
> Cc: <amradio at mailman.qth.net>
> Sent: Thursday, April 30, 2009 9:36 AM
> Subject: Re: [AMRadio] Filament choke
>
>
>>
>> Here's my schematic so far for the 160m amp:
>>
>> http://www.wd8das.net/160m-GI7B.JPG
>>
>> This one won't be a as pretty as some... I'm going to build it on a
>> steel chassis that has been used by others for at least four other
>> projects and is literally swiss-cheesed with useful holes.  (more
> holes
>> than steel maybe)
>>
>> The front panel is 1/8" aluminum sheet also somewhat holey, but
>> smoothed and now painted nicely with textured gray.  The cabinet looks
>> like it came from a later-vintage Meissner Signal Shifter with
> liftable
>> lid and plenty of ventilation holes.
>>
>> Steve WD8DAS
>>
>> sbjohnston at aol.com
>> http://www.wd8das.net/
>> ---------------------------------------------------------
>> Radio is your best entertainment value.
>> ---------------------------------------------------------
>>
>>
>>
>>
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