Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: 10W class driver, what fet?  (Read 5689 times)
M0HCN
Member

Posts: 473




Ignore
« on: September 11, 2012, 12:35:12 PM »

Ok, bit of a headscratcher here, given a power stage that needs about 5W or so of drive, HF + 6M, available supplies are 12 & 50V and I would like a push pull driver stage, what would you use?

RD15HVF1 is readily available and obvious, but ideally there would be something that could run off the main 50V rail rather then needing the 12V rail as an additional supply.

Anyone got any ideas for something else in the low power push pull class?

Regards, Dan.
Logged
KE5JPP
Member

Posts: 0




Ignore
« Reply #1 on: September 11, 2012, 03:47:06 PM »

Ok, bit of a headscratcher here, given a power stage that needs about 5W or so of drive, HF + 6M, available supplies are 12 & 50V and I would like a push pull driver stage, what would you use?

RD15HVF1 is readily available and obvious, but ideally there would be something that could run off the main 50V rail rather then needing the 12V rail as an additional supply.

Anyone got any ideas for something else in the low power push pull class?

Regards, Dan.

A pair of VRF148's would probably be overkill? 

Gene
Logged
M0HCN
Member

Posts: 473




Ignore
« Reply #2 on: September 12, 2012, 11:07:25 AM »

More then somewhat!

73 Dan.
Logged
KE5JPP
Member

Posts: 0




Ignore
« Reply #3 on: September 12, 2012, 12:30:24 PM »

More then somewhat!

73 Dan.

At 50 V, I guess you are out of luck then.

Gene
Logged
M0HCN
Member

Posts: 473




Ignore
« Reply #4 on: September 12, 2012, 03:31:58 PM »

The field does not open up all that much at 28V or 12V either, there just is not much out there that is current product, specified for linear service in this frequency range and power level.

Freescale have a 10W part, but it is unspectacular linearity wise, and there are various TO220 things intended for switching service most not specified for linear HF use, other then that, old Motorola derived parts seem to be most of what is out there, and availability on those is problematic (Even more so if you don't want to pay almost as much for the driver sand as for the pair of VRF150 for the finals).

Ah, well, RD15s it is then.

Regards, Dan.
Logged
KD8DEY
Member

Posts: 352




Ignore
« Reply #5 on: September 12, 2012, 07:45:40 PM »

Any particular reason why it would have to be a FET?
A lot of the "CB" operators use a ERF2030 mod to replace hard to find
output transistors in their radios.

https://www.google.com/search?q=erf2030&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

there used to be a bunch of plans available for QRP amps that used the old SSB CB output transistors
in push pull etc.

There is a company called ELEFlow that has been making replacements for transistors that not long ago
were considered unobtainium. I have not yet heard of any complaints and they have been in business a couple years now.
http://www.eleflow.com/

Their authorized distributor is a guy on E-Bay called weazle66
http://www.ebay.com/sch/weazle66/m.html?hash=item3f1b085d64&item=271036472676&pt=UK_Mobile_Phones_Communication_Radio_Parts_Accessories&rt=nc&_trksid=p4340.l2562
Logged
KE5JPP
Member

Posts: 0




Ignore
« Reply #6 on: September 13, 2012, 02:56:36 AM »

Any particular reason why it would have to be a FET?
A lot of the "CB" operators use a ERF2030 mod to replace hard to find
output transistors in their radios.

https://www.google.com/search?q=erf2030&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

there used to be a bunch of plans available for QRP amps that used the old SSB CB output transistors
in push pull etc.

There is a company called ELEFlow that has been making replacements for transistors that not long ago
were considered unobtainium. I have not yet heard of any complaints and they have been in business a couple years now.
http://www.eleflow.com/

Their authorized distributor is a guy on E-Bay called weazle66
http://www.ebay.com/sch/weazle66/m.html?hash=item3f1b085d64&item=271036472676&pt=UK_Mobile_Phones_Communication_Radio_Parts_Accessories&rt=nc&_trksid=p4340.l2562

Do you know what an ERF2030 is?  It is a remarked IRF510 FET.

Gene
Logged
KE5JPP
Member

Posts: 0




Ignore
« Reply #7 on: September 13, 2012, 02:58:54 AM »

The field does not open up all that much at 28V or 12V either, there just is not much out there that is current product, specified for linear service in this frequency range and power level.

Freescale have a 10W part, but it is unspectacular linearity wise, and there are various TO220 things intended for switching service most not specified for linear HF use, other then that, old Motorola derived parts seem to be most of what is out there, and availability on those is problematic (Even more so if you don't want to pay almost as much for the driver sand as for the pair of VRF150 for the finals).

Ah, well, RD15s it is then.

Regards, Dan.

Yep, the Mitsubishi RD parts are about the only ones left at a reasonable cost.  That is probably why most new Ham transceivers use them now.

Gene

Logged
KD8DEY
Member

Posts: 352




Ignore
« Reply #8 on: September 13, 2012, 11:25:29 AM »

Any particular reason why it would have to be a FET?
A lot of the "CB" operators use a ERF2030 mod to replace hard to find
output transistors in their radios.

https://www.google.com/search?q=erf2030&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

there used to be a bunch of plans available for QRP amps that used the old SSB CB output transistors
in push pull etc.

There is a company called ELEFlow that has been making replacements for transistors that not long ago
were considered unobtainium. I have not yet heard of any complaints and they have been in business a couple years now.
http://www.eleflow.com/

Their authorized distributor is a guy on E-Bay called weazle66
http://www.ebay.com/sch/weazle66/m.html?hash=item3f1b085d64&item=271036472676&pt=UK_Mobile_Phones_Communication_Radio_Parts_Accessories&rt=nc&_trksid=p4340.l2562

Do you know what an ERF2030 is?  It is a remarked IRF510 FET.

Gene

Yes i know the erf2030 is a Fet that is why I mentioned it. If you google the Mod it shows that additional parts are needed. Thats why I included a link
Logged
KE5JPP
Member

Posts: 0




Ignore
« Reply #9 on: September 13, 2012, 12:00:02 PM »

Any particular reason why it would have to be a FET?
A lot of the "CB" operators use a ERF2030 mod to replace hard to find
output transistors in their radios.

https://www.google.com/search?q=erf2030&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

there used to be a bunch of plans available for QRP amps that used the old SSB CB output transistors
in push pull etc.

There is a company called ELEFlow that has been making replacements for transistors that not long ago
were considered unobtainium. I have not yet heard of any complaints and they have been in business a couple years now.
http://www.eleflow.com/

Their authorized distributor is a guy on E-Bay called weazle66
http://www.ebay.com/sch/weazle66/m.html?hash=item3f1b085d64&item=271036472676&pt=UK_Mobile_Phones_Communication_Radio_Parts_Accessories&rt=nc&_trksid=p4340.l2562

Do you know what an ERF2030 is?  It is a remarked IRF510 FET.

Gene

Yes i know the erf2030 is a Fet that is why I mentioned it. If you google the Mod it shows that additional parts are needed. Thats why I included a link

He is not building a 10-4 Good Buddy CB amp!  Those "ERF2030" FETs are run in class C EVEN in SSB on those CBs - that is why they splatter like Hell!  No one who wants to build a quality linear amplifier would use those switching type FETs!  Good Grief!

Gene
Logged
WB8VLC
Member

Posts: 119




Ignore
« Reply #10 on: September 13, 2012, 12:15:07 PM »

MRF6V2010 from freescale is single ended but it may work.
http://www.freescale.com/files/rf_if/doc/data_sheet/MRF6V2010N.pdf

around 27 dollars at digikey
http://www.digikey.com/product-detail/en/MRF6V2010NBR1/MRF6V2010NBR1CT-ND/3524239
Logged
M0HCN
Member

Posts: 473




Ignore
« Reply #11 on: September 13, 2012, 02:20:28 PM »

I had looked at that, package is inconvenient, but a pair in push pull may just work and be clean enough that the driver does not end up dominating the distortion figures.

Plenty of gain there anyway, hold it back to maybe 15db or so with feedback and it could become very good indeed. I shall have to whistle up a pair and have a bit of a play. 

If I wanted IRF510 I already know where to find them, but they fail my 'linear, characterised for HF operation' requirement, fine as a get out of jail device when you need crude RF power NOW (and ideally when you can make do with constant carrier modes or for something like a Q switch driver), but not the right thing for what I have in mind to put on the air. 

Regards, Dan.
Logged
WB8VLC
Member

Posts: 119




Ignore
« Reply #12 on: September 14, 2012, 10:14:00 AM »


 I agree about the package being inconvenient to prototype with.

 Working on commercial Avionics RF Power amp design for the past 22 years I have come to the realization that you either pay the higher price for a real ceramic flange mount device or go the lower cost route designing with a plastic pack surface mount device that requires 50 or more backside ground vias and a more careful thermal layout.

 I'm now designing avionics pulse amps and stuck with using 250 watt mode S surface mount devices when my gut feeling and past experience has been to stick with the ceramic flange mounts.

From a replacement/servicing standpoint the flange mount part that I want to use is much more easy to remove wheras replacing the surface mount part, which has 50 vias soldered to the devices backside pad,  usually results in a damaged PCB after even one part replacement.


 I have found that these days most if not all manufacturers want to sell the cheaper plastic SM devices as opposed to supplying the more expensive, easily replaced, leaded ceramic devices.


 Good luck with whatever part you choose.


Mike
Logged
AD6KA
Member

Posts: 2236




Ignore
« Reply #13 on: September 14, 2012, 07:44:10 PM »

Quote
Do you know what an ERF2030 is?  It is a remarked IRF510 FET.
Quote
He is not building a 10-4 Good Buddy CB amp!  Those "ERF2030" FETs are run in class C EVEN in SSB on those CBs - that is why they splatter like Hell!  No one who wants to build a quality linear amplifier would use those switching type FETs!  Good Grief!

IRF-510's are used as PA devices on %80
of the QRP kits on the market. Usually in push-pull,
sometimes individually. Not suitable for this op's
project, but "splatter like hell"?
I've never had a problem.
Depends on the circuit and how they're biased.
Just a thought.....
73, Ken  AD6KA
Logged
ZENKI
Member

Posts: 916




Ignore
« Reply #14 on: September 14, 2012, 11:39:40 PM »

Use BLF175's they are excellent devices and have superb IMD performance even in class AB.

VRF148s would also be  a good choice as asuggested.

There many excellent devices available  however the manufacturers provide no IMD data which is rather poor marketing and engineering practice. What is even more astonishing is that  if you email the  engineering
departments they have no data and will make comments like "they are excellent but we have no data" Very unprofessional. When MACOM did not have any IMD data they would go measure the devices and fax you the data within
48 hours. Engineering standards are rather poor in the many takeover semiconductor companies around the world. A good case in point is Mitsubishi, they manufacture some nice RD series of fets however they have no IMD data,
pathetic really. What do their engineers do all day?

Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!