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
>
>
|
