Hello Ken,
the L and C values *calculated by you* are about correct
but_only_if_you_assume_lossless_components.
The point however is that by choosing 1.1mH at the 50 Ohm side you set a very
high loaded Q, around 40,
for the network.This means **lots** of losses in the filter which are at 300W
RF power ca. 141W according to TLW3
(assuming an unloaded Q of 100 for the Ls and 1000 for the C).
If you choose 201µH at the 50 Ohm side eff.Q is reduced to 3.8 and losses drop
to 39W.
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Clemens Paul
>Sent: Sunday, October 18, 2015 11:18 AM
>To: [email protected]
>Subject: LF: RE: RE: RE: TX Toroid Material ->Correction
>
>The schematic screenshot was empty,so here once more.
>
>P.S.The values in the smith chart plot from yesterday were
>correct anyway.
>
>73
>Clemens
>DL4RAJ
>
>
>>-----Original Message-----
>>From: [email protected]
>>[mailto:[email protected]] On Behalf Of Clemens Paul
>>Sent: Sunday, October 18, 2015 11:11 AM
>>To: [email protected]
>>Subject: LF: RE: RE: TX Toroid Material ->Correction
>>
>>Hello Ken,
>>
>>I have mixed up input and output.
>>So the correct values are 1.1mH **next to the tubes** and
>>201µH **next to the 50 Ohm load**.
>>C stays the same.
>>See RFsim screenshots.
>>
>>Sorry for the inconvenience.
>>
>>73
>>Clemens
>>DL4RAJ
>>
>>>-----Original Message-----
>>>From: [email protected]
>>>[mailto:[email protected]] On Behalf Of Clemens Paul
>>>Sent: Saturday, October 17, 2015 6:49 PM
>>>To: [email protected]
>>>Subject: LF: RE: TX Toroid Material
>>>
>>>Hi Ken,
>>>
>>>I believe two of your component values are off.
>>>I calculate 201µH for the L next to the tubes,625pF for the
>>>shunt C and 1.1mH for the second L .
>>>For the 201µH L I would use iron powder (Amidon #2), for the
>>>1.1mH #43 ferrite.
>>>Use the mini toroid calculator to find the appropiate size
>>>regarding number of turns and
>>>allowed flux with safety margin.
>>>
>>>73
>>>Clemens
>>>DL4RAJ
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: [email protected]
>>>>[mailto:[email protected]] On Behalf Of Ken
>>>>Sent: Saturday, October 17, 2015 5:41 PM
>>>>To: [email protected]
>>>>Subject: LF: TX Toroid Material
>>>>
>>>>Dear All. I am having problems with the choice of material for
>>>>the output network of the 475kHz Valve TX. The network is an L
>>>>? C ? L, ?T? network with an input impedance of 2100 ohms and
>>>>a load of 50 ohms, for this configuration the input L is
>>>>7.7mH, shunt capacitance is 117pf, and output L is 1.1mH. The
>>>>PA design using a 6146 low power or 813 high power work fine
>>>>when simulated using LT spice IV. When testing in the real
>>>>world using the 6146 there is in excess of 800v rms rf on the
>>>>network side of the anode coupling capacitor, but nothing
>>>>after the input L. I can only conclude that I using the wrong
>>>>type material for the toroids, I used the largest size
>>>>(unmarked) toroid which gave me a modest number of turns. I
>>>>have checked the Amidon tables and Iron Powder because of the
>>>>low AL values, which leaves Ferrite, which mix would you
>>>>recommend? The simulations give me output powers 90W for the
>>>>6146, and 300W for the 813. I would be grateful for any core
>>>>material advice .
>>>>
>>>>
>>>>
>>>>Ken Wright.
>>>>
>>>>M0KHW
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>
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