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Date: Sun, 12 May 2019 15:50:18 +0200
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <1272443356.20190512114532@gmail.com>
Subject: Re: LF: Another impedance matching question. Paul's audio amps.
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Hello Chris,

Am 12.05.2019 12:45, schrieb Chris Wilson:
> Can
> I initially lay insulated stranded but each single core UK 15 Amp
> mains wires on the ground's surface to the rods?
Yes, a good choice.
The rods, which DC ground resistance will they provide? You can do a 
first measurement at DC, > 50 V. Or at 50 Hz AC.

>   Is 50 yards earth rod
> spacing adequate
Use as much distance as possible. 100 yards will result in a 6 dB 
stronger signal, theoretically.
>   and should I try to get them in a ditch that's
> usually constantly wet?
Yes, preferred. You can start measuring the loop's loss resistance and 
then optimise it. I'm curious for the first results. Maybe you will be 
THE transmit station from the UK, because currently there is no one 
(amateur...).

73, Stefan
>   I picked up my amp a few weeks back, it looks
> quite a beast! Thanks Paul Nicholson :) Toroids should land this week.
>
> Saturday, May 11, 2019, 7:29:56 PM, you wrote:
>
>    
>> Hi Chris,
>>      
>    
>> Did you already lay out wires? And did you already get the amplifier?
>>      
>    
>> 73, Stefan
>>      
>    
>> Am 09.05.2019 16:47, schrieb Chris Wilson:
>>      
>>> Hello Stefan,
>>>
>>> Thanks,  ordered 3, so get free shipping, it was cheaper than ordering
>>> 2 and paying shipping :)
>>>
>>> Thursday, May 9, 2019, 2:34:58 PM, you wrote:
>>>
>>>
>>>        
>>>> Hi Chris,
>>>>
>>>>          
>>>
>>>        
>>>> I would not recommend the one you selected because it has an unnecessary
>>>> large inner diameter and a  lower height, thus a lower AL value.
>>>>
>>>>          
>>>
>>>        
>>>> I think this is the same one that i recommended from Bürklin:
>>>> https://www.mouser.co.uk/ProductDetail/EPCOS-TDK/B64290A0699X830?qs=sGAEpiMZZMs2JV%252BnT%2FvX8Df1W1GtRs010YpcsJh6dvk%3D
>>>> It is also cheaper.
>>>> There are other materials available, such as T65, T38, T37, offering a
>>>> higher AL value. Maybe these are even more suitable at that sort of
>>>> frequency but i didn't spend too much time to select the best core for
>>>> each frequency. I use the N30 material from 1 kHz to MF at high power (
>>>>
>>>>          
>>>    >>   1 kW for one core) without problems. So this is what i recommend. It
>>>
>>>        
>>>> will work.
>>>>
>>>>          
>>>
>>>        
>>>> 73, Stefan
>>>>
>>>>          
>>>
>>>        
>>>> PS: If you want to bridge one of Paul's 2x 7.2 kW amps, you may need two
>>>> of them ;-)
>>>> PPS: You may want to build two orthogonal ground loops then, one per
>>>> channel. With SpecLab you can then drive each channel separately and so
>>>> you can build a software rotatable loop by aligning the phase between
>>>> the channels, while staying into the shack when its cold and/or rainy :-)
>>>>
>>>>          
>>>
>>>
>>>        
>>>> Am 09.05.2019 14:42, schrieb Chris Wilson:
>>>>
>>>>          
>>>>> Hello Stefan,
>>>>>
>>>>> I  am  now on to building a matching transformer but it seems Buerklin
>>>>> have  a  minimum  order  of  60 units! I have found this bigger core at
>>>>> Mouser, could I use that instead please?
>>>>>
>>>>> https://www.mouser.co.uk/ProductDetail/EPCOS-TDK/B64290L0730X830?qs=4l9S5vBWkUJtsO6ZFRCS4g%3D%3D
>>>>>
>>>>>
>>>>>            
>>>
>>>
>>>
>>>        
>
>
>
>