"RF Parts" Ferrite Transformers

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"RF Parts" Ferrite Transformers

Postby WA2WVL » Sat Jan 28, 2006 11:24 pm

I have been testing some of the RF Transformer line sold by RF Parts Co.
(61 material)
The following data is for their T-2.0 transformer which is 2 inches long, uses .5 in diameter cores and has a .22 in inside hole.

At 28.0Mhz

Vrms----------Xfmr Loss

20V-----------1W------( a 13.6V application)
30V-----------2W
40V-----------4.1W----(a reasonable limit)
50V-----------5.3W
60V-----------14W
71V-----------23W

This transformer not suitable for 160M but may be made available in 43 material which would work on 160.

Floyd WA2WVL
WA2WVL
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Postby frank carcia » Sun Jan 29, 2006 2:38 pm

Floyd,
I think some of the motorola app notes used type 61 in the higher power stuff. As the flux density increases the core performances come closer for type 43 and 61 but 61 has less loss.
My pile of ENI boards used 6- 9/16 cores type 61 per stack. The loss was pretty high below 40 meters. This was with MRF429s at 48 vdc. I would think it would work at 1/4 operating Z using bigger devices at 48 volts.
Type 43 does get a bit lossy at 28 MHz. I guess the best thing to do is to shoot for the same loss on 160 as 10 for a BB rig.
A 10 meter rig I would go with 61.
Some of the ENI boards had type 63 ui=65 which was almost useless at 40 meters.
Question: You told me going to a thicker sleeve would not give expected results. What happens in a torroid or is it different since the wire loops around the core. I wonder if the strong flux remains near the surface or distributes evenly?? Thermal is not a problem because it is the outer surface unlike a sleeve??
frank carcia
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Postby WA2WVL » Sun Jan 29, 2006 4:14 pm

Frank, I do remember looking at an IR scan of a toriod and seeing a hot line under each wire.
Floyd
WA2WVL
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Postby WA2WVL » Sun Jan 29, 2006 4:25 pm

Frank:

43 works well at 30Mhz but most of the loss is dielectric loss due to the electric field. Sometimes a shield is needed.

I have the P/P pair if IRF540N's running at 28Mhz. So far 50W at 50% efficiency. Working to get it up. Peak drain voltage 35v with 14VDC.
(abt -5v swing)

I think you are right about toriods.

Floyd
WA2WVL
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Joined: Thu Dec 22, 2005 1:40 pm
Location: Homosassa, Fl.

Postby frank carcia » Sun Jan 29, 2006 6:30 pm

Floyd,
I never received any IR pictures???
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