Rik,
With 500 w there is no need for qrs anymore ;-)
You can go on CW!
73
Christian Groeger
Rik Strobbe <[email protected]> schrieb:
>Hi Christian,
>
>according to the "mini ringcore calculator" (by DL5SWB) it is just on the edge
>(a flux of 223 G while 221 G is the max. flux). But as I have sufficient
>T200-2 cores I prefer to be on the safe side, also taking in mind that modes
>as QRRS120 and WSPR will require a 2 minute carrier.
>
>For an indentical LPF filter (coil reactance remains the same) the flux will
>drop with the square root of the frequency increase. So on 475 kHz the flux
>will be double compared to 1850 kHz.
>Or otherwise said: on 475 kHz you can only use half the power you can use on
>1850 kHz.
>
>73, Rik ON7YD - OR7T
>
>________________________________________
>Van: [email protected] [[email protected]]
>namens C. Groeger [[email protected]]
>Verzonden: vrijdag 30 augustus 2013 12:09
>To: [email protected]
>Onderwerp: Re: LF: iron powder toroid cores
>
>Hi Rik,
>One T200_2 is enough for that power. I tried it on 160m at 1000w.
>Temperature was abaout 40C.
>
>Hpe cu on 630
>Df5qg
>
>Christian Groeger
>
>Rik Strobbe <[email protected]> schrieb:
>
>>Dear all,
>>
>>
>>
>>I intend to replace the air coils in the LPF on my 475 kHz transmitter by
>>toroid core coils. I have a stock of T200-2 cores but for the power level
>>want to get (500W would be required to get near the 5 W EIRP limit) one
>>T200-2 is just on the edge in regard with the maximum flux (and thus
>>temperature rise.
>>
>>To be on the save side I would use 2 T200-2 toroids for each coil, and there
>>are 2 options:
>>
>>
>>
>>1. Glue 2 cores together to make one core of the double height.
>>
>>This would reduce the flux to 70%, well under the limit. It would also reduce
>>the number of windings to 70%, but due to the double coil height the wire
>>length will increase slightly (abt. 10%).
>>
>>But as the cores have rounded egdes there wil be some air space between the
>>wire an the core, what might increase loss.
>>
>>
>>
>>2. Put 2 toroid core coils, each of half the inductance, in series.
>>
>>This will also reduce the flux to 70%, but the total wire length needed will
>>increase by abt. 40%.
>>
>>
>>
>>In option 1 I will need lees wire (= less loss) compared to option 1, but the
>>air space might undo this advantage.
>>
>>
>>
>>So my question is: what will be best?
>>
>>All advice is welcome.
>>
>>
>>
>>73, Rik ON7YD - OR7T
>>
>>
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