MRF-421 on 6M

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MRF-421 on 6M

Postby VK4HJ » Wed May 13, 2015 7:58 am

Morning all,
Has anyone had success using MRF-421 on 50 MHz?
Tnx in anticipation.
Chris VK4HJ
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Re: MRF-421 on 6M

Postby ZL2WHO » Wed May 13, 2015 3:11 pm

I wouldn't go there, look at the power gain vs freq chart here... ... F421.shtml
The gain is down at 30 MHz so i would suspect at 50MHz its very poor.
Save you $$ and make your next PA with LDMOS.. big boys toys !! These things are magic. :D

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Re: MRF-421 on 6M

Postby VK4HJ » Wed May 13, 2015 6:04 pm

Thanks for your reply Mark.
I asked the question because other hf transistors like the mrf454 work well at 50 MHz
but are only characterised up to 30 MHz.

I just want an easy booster for a 5w sdr and have an old codan PA board that might
be worth playing with if the finals MRF-421's will pump up to 6m.

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Re: MRF-421 on 6M

Postby VK5ZLR » Thu May 14, 2015 6:39 am

Coincidentally, just playing with a MRF421 based codan PA on the bench as we speak.

Not directly relevant to 6m, but the Codan PA's generally don't drive the MRF421's too hard, there seems to be quite a lot extra to be had without letting the smoke out ( yet ! ).
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Re: MRF-421 on 6M

Postby VK2XAX » Thu May 14, 2015 5:57 pm

Stick it on the bench and try it!

What have you got to lose ?



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Re: MRF-421 on 6M

Postby VK4TI » Thu May 14, 2015 6:10 pm

I do hope the smoke stays inside the device
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Re: MRF-421 on 6M

Postby VK3IH » Wed Jun 10, 2015 12:49 pm

watch the drive levels on those Codan PA's they don't need much or they will take up smoking....................
Paul VK3IH / G3ZDR South Gippsland Victoria
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