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Went Dead

Ralph Mowery
 

This should be a link to my Google drive where you can see some pix.  With the RD16HHF1  if you lay the tab down on a table with the leads facing you , you have to cross the two leads on the right of both transistors so they will match the holes in the original ubitx .  You could use the original transistors but they would have to be insulated from the heat sink.  This ubitx has been modified in several ways and the output transformer was changed. 


I was lucky in that the box I found to put it in was just the size to cut a hole in the front for the display and in the back for the heat sink.  It was an old Bud box I picked up at a hamfest a while back that someone had started a project but never finished. 

I found the heat sink on ebay from China for about $ 5 shipped.  It was about 6 inches long, but I cut it to about 4 inches 


73 de ku4pt



On Sat, Jun 16, 2018 at 12:47 PM, Roy Appleton <twelveoclockhigh@...> wrote:
I'd love to see a close up of the new finals, crossed leads and heat sink if you could!

Roy
WA0YMH

Bill Watkins
 

Very interesting and clever.  Thanks for the tip.  How closely are the RD16HHF1 equivalent to the original mosfet?  I do like being able to bolt the heat sink to the case and use the case which is already ground to handle some heat and secure things.  Like you say, not a possibility with the original mosfet.


Bill



On Jun 16, 2018, at 11:21 AM, Ralph Mowery <rmowery42@...> wrote:

This should be a link to my Google drive where you can see some pix.  With the RD16HHF1  if you lay the tab down on a table with the leads facing you , you have to cross the two leads on the right of both transistors so they will match the holes in the original ubitx .  You could use the original transistors but they would have to be insulated from the heat sink.  This ubitx has been modified in several ways and the output transformer was changed. 


I was lucky in that the box I found to put it in was just the size to cut a hole in the front for the display and in the back for the heat sink.  It was an old Bud box I picked up at a hamfest a while back that someone had started a project but never finished. 

I found the heat sink on ebay from China for about $ 5 shipped.  It was about 6 inches long, but I cut it to about 4 inches 


73 de ku4pt



On Sat, Jun 16, 2018 at 12:47 PM, Roy Appleton <twelveoclockhigh@...> wrote:
I'd love to see a close up of the new finals, crossed leads and heat sink if you could!

Roy
WA0YMH


ajparent1/KB1GMX
 

The V4 board solves the crossover problem.  

The RD16HHF is a device people have used and its a good part but its also 10$ for a pair 
from reputable sources.  Apply the mods suggested by the users of that part for best result.

As to mounting the original IRF510 there are insulator kits and silicon based heat transfer
grease that its the time tested solution.

Allison

Bill Watkins
 

What’s a V4 board, and since I’ve already ordered the 510,  that will be what I have for awhile.  


On Jun 16, 2018, at 14:00, ajparent1/KB1GMX <kb1gmx@...> wrote:

The V4 board solves the crossover problem.  

The RD16HHF is a device people have used and its a good part but its also 10$ for a pair 
from reputable sources.  Apply the mods suggested by the users of that part for best result.

As to mounting the original IRF510 there are insulator kits and silicon based heat transfer
grease that its the time tested solution.

Allison

ajparent1/KB1GMX
 

The QCX is a very different beast from the uBitx.

The QCX uses a class E final the expects the transistor to act very much like a switch.
The advantage is extremely high efficiency over 85% its typical or higher and very
little power expended in the device. The need is the device must switch fast and hard
and IRF510 and RD parts while they can do this need much more energy into the
gate to do it.  The reward is if done well a single IRF510 will do 30-40W at 12V, however
its not a drop in thing.  These are typically monoband designs.  This works well for
CW, AM, and other constant carrier modes.

The uBitx uses a series of linear amp stages that include the finals.  At best efficiency of
each stage may be 55% or lower with a fair amount of power and heat expended.
This is a requirement for undistorted SSB and multiband designs.

What applies to QCX and uBitx are very different.

Allison

Ralph Mowery
 

The V4 board is the latest ubitx circuit board.  It has several modifications to it from the original ubitx circuit board.  One of the main ones is the audio IC was replaced by several transistors as there seems to be a real quality control problem with the original IC.  

Mr. Farhan is looking at all the mods that have been made by others and using some of the best of them in the V4 boards.

While the original works very well for the price there have been lots of modifications to it and the software.  I think he did a great job of making the original by keeping the price very low.  While I can not do much with the engineering of the electronics, I have enjoyed making some of the modifications to the ubitx.  I look at this as the way I am at chess.  I know how each piece moves, but when playing with a real chess player I get beat in about 3 moves because I don't know how to hook it all together.

The IRF510 can be mounted by using the insulators.  I don't know much about the IRF510 but the RD16HHF is a 'real' RF device and the specs say it will withstand a SWR of about 20 :1 .  However it is about $ 10 per pair instead of the $ 1 a pair for the IRDF510s.

de ku4pt


On Sat, Jun 16, 2018 at 3:09 PM, Bill Watkins <kf7yxs@...> wrote:
What’s a V4 board, and since I’ve already ordered the 510,  that will be what I have for awhile.  


On Jun 16, 2018, at 14:00, ajparent1/KB1GMX <kb1gmx@...> wrote:

The V4 board solves the crossover problem.  

The RD16HHF is a device people have used and its a good part but its also 10$ for a pair 
from reputable sources.  Apply the mods suggested by the users of that part for best result.

As to mounting the original IRF510 there are insulator kits and silicon based heat transfer
grease that its the time tested solution.

Allison
_

Roy Appleton
 

Thank you very much for the information!

Roy
WA0YMH

On Sat, Jun 16, 2018, 1:21 PM Ralph Mowery <rmowery42@...> wrote:
This should be a link to my Google drive where you can see some pix.  With the RD16HHF1  if you lay the tab down on a table with the leads facing you , you have to cross the two leads on the right of both transistors so they will match the holes in the original ubitx .  You could use the original transistors but they would have to be insulated from the heat sink.  This ubitx has been modified in several ways and the output transformer was changed. 


I was lucky in that the box I found to put it in was just the size to cut a hole in the front for the display and in the back for the heat sink.  It was an old Bud box I picked up at a hamfest a while back that someone had started a project but never finished. 

I found the heat sink on ebay from China for about $ 5 shipped.  It was about 6 inches long, but I cut it to about 4 inches 


73 de ku4pt



On Sat, Jun 16, 2018 at 12:47 PM, Roy Appleton <twelveoclockhigh@...> wrote:
I'd love to see a close up of the new finals, crossed leads and heat sink if you could!

Roy
WA0YMH

Bill Watkins
 

Thank you 

Bill Watkins
 

Thank you 

Bill Watkins
 

Replaced both IRF510 with lead-free version.  Used insulator kit.  Installed fan.  Did PA bias. Up and running again. Thanks for all suggestions. 

Bill
K0WHW