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rci2970n2 bias help

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  #17  
Old 06-05-2011, 04:42 PM
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Posted By DXMan:
Quote:
Many of the N2 were coming out doing 300 watts (I also heard of one that was doing close to 400)- but this does mean that they were rated at 300.

Have you tested any of the 2nd version's yet? I have heard of several now that are coming out of box doing around 215/225 - which is what they should be doing.

I had mine retuned from the factory 300 watts down to 215, I am now running it on a 36 amp P.S. - draws 18 amps on SSB (which is what the manual states it should draw).
73
Jeff
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Old 06-05-2011, 06:23 PM
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Thank you jeff for taking the time to help me. Maybe someone with more knowledge will step in and give me the right voltage for the irf520. You know i can not find the service manual for the ept-695015a board.Maybe rci just have not put it out yet sure would be a big help.

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Old 06-05-2011, 06:46 PM
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Have you e mailed Ranger to see if they can advise?


73
Jeff
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Old 06-05-2011, 08:09 PM
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From what I've found out was; the first production N2's were coming out with the "gate voltage" to high, this was causing the failure of the Mosfits. Guys were seeing 300 watts with a 50-60amp draw.

So after I found this out, I then sent mine into DTB radio for his complete alignment/tune. I explained what I had found out and to check the "gate voltage" and set to radio to do no more than 225 watts with roughly 18 amp draw.

Well the radio came back doing the 215-225 watts and 18 amp draw which was prefect for me. Now the radio is running cool and I am using just a 35 amp P.S..

The 2nd version is now working better than the first. From what I have been hearing, Ranger has gotten the wattage down lower (around the 200 watt mark) now and they seem to be doing better.

One more thing - I have heard of (2) of first series N2's blow up and sent back to Radio Active Radio for repair (which is where they were first bought and tuned), repair bill on one was around $200. This came right from the owner! So.......as we all know.......................................!!!

PS - I have no idea what the gate voltage is.
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Last edited by DXman; 06-05-2011 at 08:24 PM.

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  #21  
Old 06-06-2011, 09:02 AM
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I really appreciate all of you taking your time out to help me with the irf520 mosfet gate settings. I sure have learned a lot about mosfets in the last few days lol. Would i be right in saying rci should have used a power mosfet like a erf7530 or something close to it?

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  #22  
Old 06-06-2011, 09:27 AM
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Hey, its what we do forums for.
No problemmo . . .

The ERF-7530 is mfd by the owner of Magnum radios, Sam Lewis/EKL components. In fact, all of the ERF-series MOSFET's are made by EKL. RCI/Ranger USA isn't going to buy EKL parts. That would be like Chevy buying their motors from Ford!

The EKL brand makes their devices specifically for RF applications. Most of the IRF-520 'x' MOSFET's are not built for RF signals and only one or two of them will work for RF apps. If you are going to replace a MOSFET device; I would stick to the EKL brand - IMO . . .
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  #23  
Old 06-06-2011, 12:16 PM
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I emailed ranger tech support last week. And chip sent me all the info that they had right now regarding the rci2970n2. I hope this info will help others. I will let Jeff put this were he thinks it should go.

Sorry for the delay. They are still working on a service manual for this model.



The 2970DX manual can be used for alignment as it is the same with exception of the driver and final transistor alignment which is as follows.



Turn carrier and mic gain control on front to minimum.



Turn mode switch to SSB



Key transmitter and set the following voltages measured on the gate of each transistor



MAIN BOARD



Driver gate voltage 3.6VDC +-.1VDC

Final gate voltage 3.4VDC +- .1VDC



PA BOARD



Bank 1 VR-2 gate voltage 3.5VDC +-.1VDC

Bank 2 VR-3 gate voltage 3.5VDC +-.1VDC





Please note also same alignment as in service manual except higher wattage listed below.



Carrier should be set to no more than 100 watts at max power AM/FM

SSB should be set to no more than 200 watts PEP at max power SSB





Regards,



Chip



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  #24  
Old 06-06-2011, 12:56 PM
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Thank you for posting the reply, I am sure it will help others that are looking for the same info.

73
Jeff
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