Re: LF: Poor aerial connection affecting gate waveforms??

[Andy Talbot <andy.g4jnt@gmail.com>]

There is nothing complicated about ferrites used in transformers.    You don't need "original"materials.  In fact it would benefit greatly from using more modern materiuals and FETs

 The SMPSU world has supplied all you need.   There are thousands of suitable cores out there.   Gapped ferrites (also common in the SMPSU world) give you inductors

'jnt

On 15 April 2017 at 17:56, Clemens Paul <cpaul@gmx.net> wrote:

 >Taking  everything , via  the  , what appears to  be , a step  up ,
>transformer , will  provide  isolation  from  the  Ae  , if
>you combine  at
>50 ohms , then  everything  will  pass  back to the  amps , via the
>combiner ,
...
>Could be  totally  wrong  of course

Any change of the load impedance (R,X) on the secondary side
is seen by the PA on the primary side proportionally to the step up ratio.

>Why not  simply  build a  copy  of the   Decca  out put  stage
>,  series
>tuned cct's  and the  3 -2-1  adding  transformer

Perhaps because it is not so easy to get hold of those original transormers and chokes
within due time?
On the other hand i find that what Andy calls "complicated splitters/combiners" is not applicable
for the design used by Jay.
What could be simpler than slipping a bunch of easily available toroids over two pieces of coax
and add a resistor?

73
Clemens
DL4RAJ



>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Graham
>Sent: Saturday, April 15, 2017 6:27 PM
>To: rsgb_lf_group@blacksheep.org
>Subject: Re: LF: Poor aerial connection affecting gate waveforms??
>
>Can only go  by the  images  in the links  I sent a while back
>.. I was
>wondering,  after  Andy's  last post ,
>
>Why not  simply  build a  copy  of the   Decca  out put  stage
>,  series
>tuned cct's  and the  3 -2-1  adding  transformer
>there  must be enough  of them  about,  for the  transformers
>and chokes to
>be  identified , the  same  or  similar must be  about ..
>tried and tested configuration ?
>
>Taking  everything , via  the  , what appears to  be , a step  up ,
>transformer , will  provide  isolation  from  the  Ae  , if
>you combine  at
>50 ohms , then  everything  will  pass  back to the  amps , via the
>combiner ,
>
>Could be  totally  wrong  of course, but there must of  been a
> reason  for
>the  lay out ,  when  other  multi unit  pa's  used  50 ohm  combining
>networks
>but its  tried and  tested and  what's better  than  2   500w power
>modules ? .. 3 of course ,)
>
>73-G,
>
>
>
>
>
>--------------------------------------------------
>From: "Chris Wilson" <dead.fets@gmail.com>
>Sent: Saturday, April 15, 2017 3:10 PM
>To: "Graham" <rsgb_lf_group@blacksheep.org>
>Subject: Re: LF: Poor aerial connection affecting gate waveforms??
>
>> Hello Graham,
>>
>> Saturday, April 15, 2017, 2:14:17 PM, you wrote:
>>
>>>
>>>
>>> Chris,
>>>
>>> I assume , due to the  Q any small  variation , will  move  the
>>> tune  point  about , but  looking  in the   data base , Signals ,
>>> better last night  to  sv8 than  the   previous night , and  may be
>>> up  1 db at pa7  , not to say  the  noise was less , but  at  -10 db
>>> that level   will  be  much  higher  than the  local noise level ,
>>> should be a  reliable  indication
>>>
>>> How important  are the  wave forms ?
>>>
>>> 73-G,
>>
>>
>> I don't know how important they are I am not a FET ;) All I know is
>> the output transformer and the LP filter bank central toroid
>run a lot
>> cooler if the wave forms aren't all spiky. I hope someone can say how
>> critical this is? Nothing went pop, so presumably not ultra critical,
>> but heat = lost power I would think? Cheers G!
>>
>>
>> --
>> Best regards,
>> Chris                            mailto:dead_fets@gmail.com
>>
>>
>
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