What¡¯s a V4 board, and since I¡¯ve already ordered the 510, ?that will be what I have for awhile. ?
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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
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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
|
THat part is fairly close to the IRF530 and would work ok for the lower bands.
Input capacitance 350pf, robust current at 16A peak, still power limited due to
the device package to 25W.
I've tried the P16NF06 and it was high input capacitance, it was fine for 160 through 40
but getting it to go at 10M required a vastly different circuit due to the low input impedance.
There are a slew of nearly the same parts in the same case characterized as switches but
few that?have been tested for linear amplification and then only by hobby users.? Its the
price paid for cheap.??
I can suggest a list many I've not tried.? But my preference leans to LDMOS and other RF
characterized devices.? ?Many are not cheap like IRF510 but they tend to be very durable.
Then again in the 5 to 55$ range you get what you paid for (least from reliable sources).
Allison
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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
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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
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Re: Exciting times in the uBITx world
Just ordered my 2,8 display. I guess that leaves 5999 ?Bitx users left to order theirs. Not in a rush because this will be for my next ?Bitx. My first will be primarily used for barefoot digital and transverter??driver for 6 & 2.
On Sat, Jun 16, 2018 at 12:56 PM, Kees T <windy10605@...> wrote: On Fri, Jun 15, 2018 at 09:01 pm, Mike Woods wrote:
Always good to see a nice crisp summary.?
It's just amazing what Ian Lee, KD8CEC, is able to do while keeping the original uBITX Raduino with the Nano microcontroller through extensive use of the microcontroller on the Nextion. Hats off to you Ian, you sure know what
you are doing.
73 Kees K5BCQ?
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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
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Hi,
Don't use the light bulb to sort things. If you don't have the gear or the knowhow you might find somebody at a local radio club who can help you. I haven't read all of your posts but maybe the problem is not your radio at all. For instance..do you already know that your antenna system works? As in..it has made QSOs for you with a different radio?
73,
Bill KU8H
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On 06/16/2018 01:27 PM, W8SWG wrote: Well thanks for everyone's help but it is apparent that I do not have
the technical expertise to debug this radio. I have given every bit of
the patience I can muster. I will have to try to find someone to repair
it for me before I kick it across the room.
_._,_._,_
--
bark less - wag more
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Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels
#ubitx
#ubitx-help
|
Well thanks for everyone's help but it is apparent that I do not have the technical expertise to debug this radio.? I have given every bit of the patience I can muster.? I will have to try to find someone to repair it for me before I kick it across the room.
|
Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels
#ubitx
#ubitx-help
My RX with the modified audio chain. I am able to get much better audio with this MCP6284 amplifier that I had laying around from another project. I power the amp from a separate switch mode supply since it takes max 5V (no problem with noise, the PSU is very well decoupled). 
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? Hi all ! ? I just wonder if anyone have tested with P16NF06 in the final PA?? for uBITX ?? 73 de sm6mpa/Hasse/Gothenburg/Sweden ? ?
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Hi Bill,
There are a lot of reports of QSOs with the Light-bulb-dummy-load antenna. It happened to me too and sometimes the distances were pretty good - several hundred miles. It's what we had. Our transmitters did not require a 50 ohm load to function well.
Take a look in our radios now. The are output filters and those do not work if the load is very far from 50 ohms. Some of us get away with using 75 ohm coax but that doesn't give us a wild 'SWR' and doesn't necessarily look like 75 ohms to the transmitter. The finals can tolerate it and everybody is happy. SWR's that run far afield can expose your finals to higher voltages and destroy them. The old tube gear is more reliable and cleaner if we tune it into a 50 ohm dummy load and then arrange for it to see a 50 ohm antenna system. There is no reason not to do it that way. By the way, 50 ohms has become a defacto standard. It could easily have been 32 ohms, 75 ohms, 110 ohms or whatever. But everythong critical is now designed ofr 50 ohms so just go with it.
A couple of seconds into a light bulb is not going to hurt most of the time maybe never. The information obtained that way is inadequate for regular operation. So there is not much point in using the light bulb dummy load. It's just an interesting show n tell item and it could risk your output transistors if overdone. "Hold my beer and watch this."
73,
Bill KU8H
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On 06/16/2018 12:41 PM, William Cullison wrote: Off topic but you brought back memories. As a novice back in 1966, my
DX-40's only dummy load was a 75w bulb. I even got my "Rag Chewers Club"
certificate on said "dummy load."
_._,_._,_
--
bark less - wag more
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Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels
#ubitx
#ubitx-help
Latest update: I have solved the clicking issue when operating the VFO. The cause is that the Si5351 chip is very sensitive to noise on its VDD inputs. The design of the decoupling seems to be insufficient because the 3,3V is taken from the Arduino Nano regulator via a fairly long supply trace on the PCB and there is only a 0,1uF capacitor on the VDD inputs. Solution: I soldered in a 1000uF electrolytic cap over the VDD input on the Si5351. Problem solved.... See attached schematic and pic. My uBitx version is V4.   
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CAUTION!? The impedance of an incandescent bulb varies greatly over the range of
power you might send to it.? It can be as low as a few ohms and as high as several
hundred ohms.? While it may work as an impromptu dummy load it can also damage
solid-state RF PA stages.? Solid-state finals are not like hollow-state designs.? The
solid-state output stages will try to produce all the power you send through them...right
up to the point of failure.?
Arv? K7HKL
_._
On Sat, Jun 16, 2018 at 10:43 AM Bill Cromwell < wrcromwell@...> wrote: Hi
A light bulb works as a very quick n dirty go/no-go check. Even with the
newfangled solid state gear. But you still need that dummy load and some
sort of SWR bridge for regular operations. Even with legacy tube gear.
You may as well get those and leave the light bulbs alone.
73,
Bill? KU8H
On 06/16/2018 12:26 PM, RICHARD wrote:
> Buy a few pieces of cheap test equipment.? A dummy load. Cheapo watt
> meter/vswr meter and RF probe. If you can¡¯t afford this get someone to
> fix it for you, before you do need a new board,? ?Alight bulb is not the
> way to go.
>
> 73? k6kwq
>
>
>
> Sent from Mail <> for
> Windows 10
>
>
>
> ------------------------------------------------------------------------
> *From:* [email protected] <[email protected]> on behalf of W8SWG
> <ebay@...>
> *Sent:* Saturday, June 16, 2018 4:47:08 AM
> *To:* [email protected]
> *Subject:* Re: [BITX20] TX Debug Steps?
>
> So if I get some light from a bulb it is putting out RF but still not
> getting contacts.? What else could the problem be?? Do I need to buy a
> new board?
>
--
bark less - wag more
|
Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels
#ubitx
#ubitx-help
If usiing a low impedance speaker (4 to 8 ohms) it might be interesting to try bridging across
C-74 with a 220 mfd capacitor.? Observe polarity, positive toward transistors and negative
toward speaker.? This should add more LF to the speaker output.? Farhan mentioned that this
output works best with 32 ohm or higher impedance earphones, even though it will drive small
speakers.
Arv? K7HKL
_._
Raj, VU2ZAP: here are the voltages you asked for. 
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Re: Exciting times in the uBITx world
On Fri, Jun 15, 2018 at 09:01 pm, Mike Woods wrote:
Always good to see a nice crisp summary.?
It's just amazing what Ian Lee, KD8CEC, is able to do while keeping the original uBITX Raduino with the Nano microcontroller through extensive use of the microcontroller on the Nextion. Hats off to you Ian, you sure know what
you are doing.
73 Kees K5BCQ?
|
Re: VOM Advice? Simpson 260
For VOM advice, I'd go look through the EEVBLOG forum's Test Equipment section. One of the first posts in there is a spreadsheet of 210 meters in 38 brands, and discussions of many more. And that's just one post. The EEVBLOG YouTube channel has many videos on the subject of meters, even head-to-head competitions between them at different price classes. Heck, Dave Jones, creator of EEVBLOG, has a couple of his own meters on the market. I'd love to try one of his, someday, just to see how it compares with my Fluke.
This should give you some options, and perhaps some input on what the problems you need to be aware of are or could be.
https://www.youtube.com/results?search_query=eevblog+multimeter
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I'd love to see a close up of the new finals, crossed leads and heat sink if you could!
Roy WA0YMH
On Sat, Jun 16, 2018, 11:36 AM Ralph Mowery < rmowery42@...> wrote: While they cost close to $ 5 each? you may want to look at replacing the outputs with some RD16HHF1.? One good thing is the tab is at ground so you can bolt it directly to a heat sink.? You will have to cross two of the leads as the pinout is slightly different.? I did this and put a very large heat sink on mine to handle the extra heat from doing other mods to get the power up on some of the bands.
de ku4pt
|
Hi
A light bulb works as a very quick n dirty go/no-go check. Even with the newfangled solid state gear. But you still need that dummy load and some sort of SWR bridge for regular operations. Even with legacy tube gear. You may as well get those and leave the light bulbs alone.
73,
Bill KU8H
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Show quoted text
On 06/16/2018 12:26 PM, RICHARD wrote: Buy a few pieces of cheap test equipment. A dummy load. Cheapo watt
meter/vswr meter and RF probe. If you can¡¯t afford this get someone to
fix it for you, before you do need a new board, Alight bulb is not the
way to go.
73 k6kwq
Sent from Mail <> for
Windows 10
------------------------------------------------------------------------
*From:* [email protected] <[email protected]> on behalf of W8SWG
<ebay@...>
*Sent:* Saturday, June 16, 2018 4:47:08 AM
*To:* [email protected]
*Subject:* Re: [BITX20] TX Debug Steps?
So if I get some light from a bulb it is putting out RF but still not
getting contacts. What else could the problem be? Do I need to buy a
new board?
--
bark less - wag more
|
Off topic but you brought back memories. As a novice back in 1966, my DX-40's only dummy load was a 75w bulb. I even got my "Rag Chewers Club" certificate on said "dummy load."
|
Gwen Patton