Message-ID: <EA2B903E014047529F5EA254C3A63271@DELL4>
From: <jrusgrove@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
References: <1019495001.20190502130019@gmail.com> <D5406E34951346E9B5C8CCF68B297844@DELL4>
Date: Thu, 2 May 2019 10:14:16 -0400
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Subject: LF: Re: Re: Toroids
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Sorry ... my last e mail was supposed to go to Chris directly. For unknown reasons when I selected 
'reply'. to Chris's direct e mail Blacksheep got filled in as the address instead of  his direct e 
mail. That's a head scratcher ... never seen that one happen before!

Jay W1VD


----- Original Message ----- 
From: <jrusgrove@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, May 02, 2019 10:01 AM
Subject: LF: Re: Toroids


> Chris
>
> None in stock but would be happy to get them for you. Only possible problem is the customs forms 
> ... I'm required to list the values of items accurately. I had a run in with US Customs years ago 
> and don't wish to take a chance getting tangled up with them again. Let me know and I'll check 
> pricing for the cores and shipping.
>
> A pi-type filter is what's required for current mode. The amplifier as shown in the schematic 
> 'appears' to be current mode since there's no bypass at the centertap of the transformer. Not sure 
> why you're seeing hot components. In the schematic it appears the ground was left off the bottom 
> of LPF capacitors ... I'm sure
> you picked up on this. Don't think I'd use a -26 core at 500 kHz ... this may or may not be the 
> problem.
>
> Jay W1VD
>
> ----- Original Message ----- 
> From: "Chris Wilson" <dead.fets@gmail.com>
> To: <jrusgrove@comcast.net>
> Sent: Thursday, May 02, 2019 8:00 AM
> Subject: Toroids
>
>
>>
>>
>> Hello  Jay,
>>
>> I  am going to build the MF version of your 1kW amp deck to compliment
>> the  LF  versions that have proven superb! I am struggling getting the
>> T-225A-2  toroids  and  the T-157-3 ones here in the UK without Amidon
>> trying  to  charge  far  more  than  the cost in postage, plus a hefty
>> import  duty  /  tax.  Would  you  consider supplying these direct and
>> marking  the package note as a low value (at my risk)? I could do with
>> three  of T-225A-2 and 4 of the T-157-3 toroids. Here in the UK no one
>> has  any  stock of either. If it's a PITA and you are unable to oblige
>> or you don't have them, no worries :) Thanks. Chris Wilson 2E0ILY.
>>
>> BTW, off list, I built the G0MRF MF 300W amp and at full power it runs
>> the  toroids  and  C19  C20  mad  hot,  plus  the drain waveforms look
>> horrible.  Am  I  right in thinking he's using a current mode LPF on a
>> voltage  mode  amp?  And  are  the  components  like  caps and toroids
>> marginal  at  this  power  level?  I  am sure your MF amp is much more
>> robust :)
>>
>> -- 
>> Best regards,
>> Chris                          mailto:dead.fets@gmail.com
>
>