[AMPS] rollers

[measures]

>
>
>> >No, it has air insulation.
>> 
>> The coil-form has air insulation?  Did you mean to say ceramic insulation?
>
>Air.
>
How?

>> > >The Oren Elliot Products roller was never used at Ameritron.
>> 
>> Where did the Delrin roller inductor come from that reportedly melted down
>> twice in the ARRL lab? thanks > cheers, Tom
>
>Don't know. Ameritron never used the Oren Elliot Products roller.
>
>But I can tell you this, the Q difference between ceramic and 
>Delron when only the roller material is changed is minimal. The Q 
>of the OEP roller measures about 110 at 3 MHz, the same size 
>ceramic core inductor measures 132 both at full inductance.
>
>The actual problem is the wire gauge and resistivity, and the fact 
>there is little air circulated across the roller winding, which heats 
>primarily from I^2 R losses. As little as 50 watts of heat can ruin an 
>OEP roller. Replace it with a ceramic core roller, and the same 
>dissipation rises to over 125 watts.

How do you measure disipation in the inductor?
>
>WA1OXT is using two ceramic form rollers in a tuner designed by 
>you, 

I did not design the balanced L network tuner in Feb.1990 QST.  .  It was 
from Bell Labs research in the 1930s.

> and it has severe heating problems on 160 meters. 

Extraordinary.  L networks have the lowest Q possible.  

>Fortunately ceramic melts at very high temperature.
>
>To cure the problem, he needs to switch to a large gauge 
>conductor in the rollers.
>
most people that have built the balanced L Tuner use 12ga variable 
inductors.

later, Tom.  

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