Let me make a correction on the size of toroids they've been using. Instead of
1/4" thick, they used 1/2" thick, 1/2" OD, and 0.3" ID. Palomar number F-50B.
1/4" thick is almost as much in price as a 1/2".
Will
*********** REPLY SEPARATOR ***********
On 3/7/06 at 10:05 PM Will Matney wrote:
>Dan,
>
>*********** REPLY SEPARATOR ***********
>
>On 3/7/06 at 5:55 PM Dan Sawyer wrote:
>
>>Should mix 67 support a 1.8 to 55 MHz 1200 watt transformer?
>
>
>I'd give Amidon or Fair-Rite a call or an e-mail and ask them their
>recommendation.
>
>
>>
>>On this topic:
>> 1. What physical form should be used?
>
>
>Just stack two sets of toroids side by side like everyone does. You'll
>need tow pieces of 1/4" dia. brass tubing and some PC borard to make them
>up along with some teflon covered hookup wire.
>
>
>> 2. What is a reasonable turns on the 50 Ohm side (to start design).
>
>
>Well, it's according to what the base and collector impedance is of the
>transistor you plan to use. It's generally listed on their spec sheets.
>Take that impedance and multiply it by two (for two transistors) to get
>the total impedance. Then divide that by the line impedance which most
>likely is 50 ohms. The ratio you get from that most likely will either be
>16:1 or 9:1. Take either 9 or 16 and get the square root of that, and that
>is the number of turns for the wire (4 or 3). The other one is only one
>turn by the tubing. Then you need to multiply the line impedance by at
>least 4 to get the reactance for the transformer which for 50 ohms is 200
>ohms and is what about all uses. Then figure the inductance of the coil by
>the number of turns and the AL value from the number of toroids you'll
>have. You have to have the inductance (L) to check the reactance as XL =
>2 pi F L. You need enough core together to equal this. A check that you
>have enough core should be done to see that y
> our below the maximum flux density also by using the standard flux
>density formula. Ferrite has a rather low flux density, something around
>1500 gauss (according to what material). For a 100 watt set, the usual
>stack lengths are 1/2" long for the input (for about 10-20 watts PEP in),
>and about 2" long for the output using 1/2" OD by 1/4" ID by 1/4" thick
>toroids. If I used 43, I'd make that 2" length a little longer, maybe
>2-1/2" which will help it not get as hot. One other place to get some info
>would be CCI here in Ohio (Communications Concepts Inc.). I think they
>have the old Motorola app notes there they use.
>
>http://www.communication-concepts.com/
>
>
>>
>>Dan
>>
>>R@contesting.com;Measures wrote:
>>
>>>On Mar 7, 2006, at 9:03 AM, Jim Brown wrote:
>>>
>>>
>>>
>>>>On Tue, 7 Mar 2006 08:56:08 -0800, R@contesting.com;Measures wrote:
>>>>
>>>>
>>>>
>>>>>On an oscilloscope, using 100w of RF, I observed that mix #61 begins
>>>>>to
>>>>>distort the waveform at c. 13MHz. Those who don't desire to generate
>>>>>harmonics should probably follow the manufacturer's specs and not
>>>>>operate 61 above 10MHz.
>>>>>
>>>>>
>>>>The distortion and losses will depend on many variables, including the
>>>>power level, the size of the core, and the number of turns.
>>>>
>>>>
>>>
>>>Agreed. Waveform distortion is the result of of a combination of too
>>>many Webers and too much f.
>>>
>>>
>>>
>>>>What were your
>>>>test conditions (core size, turns, etc.)?
>>>>
>>>>
>>>
>>>I don't remember the details, Jim, however, as I recall it was a 2.4"
>>>mix-61, mu=125, core for a 450-ohm 8170 grid terminator R. Whereas
>>>everything looked wonderful on the 'scope at 1W, at 100W, it did not.
>>>After I read Permag Pacific's tech specs on mix-61, it was apparent
>>>that the seller didn't. As a result of seeing the harmonic distortion
>>>above 13MHz with 100W, I switched to mix-67 (mu=40, rated by mfg at
>>>80MHz max) and observed a clean sinewave at 29MHz.
>>>
>>>
>>>>Jim Brown K9YC
>>>>
>>>>
>>>>_______________________________________________
>>>>Amps mailing list
>>>>Amps@contesting.com
>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>Rich Measures, 805.386.3734, AG6K, www.somis.org
>>>
>>>_______________________________________________
>>>Amps mailing list
>>>Amps@contesting.com
>>>http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|