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Which brand MOSFETS for RCI2970N2 ?

K

k2cb

Member
May 1, 2012
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I need to repair a 2970N2 with blown MosFets. Looking to order some from Mouser or DigiKey.

Can someone recommend which are the best MFG and/or suffix?

Vishay? Infineon? 520, 520N?

Anyone try 530 or 540s instead? Any advantage?

Thanks,
Eric
 

The best choice would be what was in there to start. Once fixed make sure the radio is not over-tuned and the owner needs to watch his SWR very close. These newer mosfet radio's are not very forgiving when it comes to an antenna issue.
 
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I posted that info on here somewhere already. Maybe you could search it?

You must replace all 8 from the same batch or there will be an imbalance in the force. Good chance they will be from RF Parts you will see.
 
Who matches hfe's on non-rf msfets? Get real! most large OEM do not match tubes and they do not match hfe's that tightly either during production. Any hfe matching is being done in house not by large scale distributor. If you get from same lot they should be on the same die and close in hfe for a non-rf mosfet that is. Does RF-parts even hfe match mosfet's that are non-rf?
 
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Most of these mosfets are cracking or chipping in the 2970N2's that fail. I would love to see cracking and chipping linked to matching issue for a non bipolar transistor. The circuit isnot even the same as the N4 cicuit so it is like comparing apples to oranges. In the RF Limited FX75-150 previously they used that same circuit with mrf 455's they had them with a single and a dual MRF455 well a single at the very least and it was called the DX100 Kit. I know I bought one in 1991 or 1992 in High School for my RCI 2950 because the RCI 2970 did not have feed back circuit yet and they had stability issues. Back than the RCI 2950 cost $495 retail from AES but if you ordered 5 you got a 30% shop discount which I got. RF LImted just modified the circuit for the mosfets it was the same basic design it had with the MRF455 before. That was my first non-CB radio and I graduated Class of 1992 from Hinseville Ga! The first export rig I saw was an HR2510 the second was an AR3500 and the third was an RCI2950.

Fairchild is the safest bet.
 
Onelasttime said:
Who matches hfe's on non-rf msfets? Get real! most large OEM do not match tubes and they do not match hfe's that tightly either during production. Any hfe matching is being done in house not by large scale distributor. If you get from same lot they should be on the same die and close in hfe for a non-rf mosfet that is. Does RF-parts even hfe match mosfet's that are non-rf?
Click to expand...
These ARE used in the RF output section of the mentioned radios. If you match them within a certain range there is no need for rebaising since FETS share the load more equally than Bipolar transistors.
They do match them at manufacturing facilities. The ERF7530 have a code that indicates they are matched.
It is the specification listed as Vth which is a letter code after the base part number.
http://www.ralphselectronics.com/ProductImages/SEMI-ERF7530.PDF
 
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