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Re: UBITX. FT8 heat sink requirements #ft8 #ubitx

Bo Barry
 

I too don't note much heat on them but the little 3904s sure heat up.?
I did put one of the tiny Raspberry pi 5v fans with a dropping resistor to give them a little air. You have to add a 7805 regulator or hook onto the big on on the Raduino.
Bo W4GHV?
Re: ubitx & case #ubitx

Bo Barry
 

But unfortunately he's 2000 miles away and I can't help him . ?. ?He is a great QRP lifelong ham too!
Re: Github's future?

 

Microsoft has done a good job with Minecraft after buying it from Mojang. I¡¯m keeping an open mind.
Re: RF power chain mods and improvements..

 

One comment on higher power...

The T30-6 toroids are way to small for more than 10W.? So all the low pass filters in
the corner wold require revisiting.

Most people at 10W use T37-2 or t37-6 and designs for higher power T50-2
and t50-6.?


Allison
Re: RF power chain mods and improvements..

 

Jerry,

I can post in 18 point type if need be.? Why so large in you posting?

The 2n2369A smt has a suffix and I'd have to look it up.? Last time I ordered it it was 4 years ago.
That is what datasheets are for.??it would only be better than the 2n3904.? It would not be better than
BFR106 what I used

I used the original cores.? I may change them later.

For more than 10W you on your own to experiment there.? I never considered more than 10W as
it was not the stated goal.? ? A reminder if you want more power the rule is quadruple.? If you going
from 5W the next stop is 20 and from 10W its 40.??Anything less is not going to show on the other
guys S meter.? ?FYI typical power steps are 1,5,20 for portable manpacks that can vary power.
Why?? As it takes that much to make a difference.

IF you going for higher power make sure the stages before the finals can supply the needed
drive.? ?You can't use wimpy transistors there.? I would never use SOT parts when I need
watts of power there is no way to cool them well.

I did change the DC fed to the finals and changed it back.? No advantage at 10W.

For driver and predriver SOT anything will not work.? Your on your own to try them
and figure out how to mount them on the existing board.??I specified TO18 for a
reason I've stated many times before.? Note: The four in the driver are required
at time to produce at least a half watt of power if not more.

C77 to ground the output side of the 470uf cap.? It keeps the cap charged
when nothing is plugged in.? ? Why in the world would I put it on C74?

For now Q11 and 12 are the existing 3904s and may be changed.? Need to test first.

One Note, The list of things are what I did and if you copy them and copy means
EXACTLY what I did it may behave the same.? ?Any variations are not what I did
and cannot even guess the result.? I may add its the current state of my radio
and is subject to change.? ?The goal was 10W and not less than 1-2 watts less
on 10M (I'm close).

Allison
Re: ND6T AGC question

Daniel Conklin
 

Mike,
I'm glad you posted this because I hadn't thought of it before.? I put a 6V regulator in the supply line for the audio amp.? The regulator cost 29 cents, so that could be a good way to power the AGC board without attempting to cut other traces, which is an operation that makes me nervous.
Dan, W2DLC
Re: ubitx & case #ubitx

Daniel Conklin
 

That's a shame because there are really no changes necessary.? Just put it together correctly and it will work
Re: UBITX. FT8 heat sink requirements #ft8 #ubitx

 

On Sun, Jun 3, 2018 at 09:44 am, Ghericoan wrote:
what current and voltage do you run when doing WSPR?
?
I don't want to become famous for this, but I accidentally ran a WSPR transmission on 40 M without the antenna connected.? My PS is 12V.? I don't know what the current draw is.? The heatsinks are stock with no fans.

The finals got very hot.? I do not recommend this procedure.? I did not have any reports for that transmission on the map.

The finals survived to transmit after they cooled off.
Re: Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?

 

49.152 MHz crystals can be obtained in fundamental mode (mostly in SMD package; 5x7mm is not too difficult to work with, but smaller packages certainly are), however, check datasheets carefully and confirm with manufacturer if in doubt, as many also are offered in 3rd overtone or don't specify. Above 49.152 MHz, fundamental mode crystal seem to be rare.

That said, I believe the project should consider making the 45 MHz filter normally used in the project available for sale to homebrewers as a component or spare part (perhaps in quantity increments of 1, 10, 25, or something like that); this would greatly help those that want to duplicate or otherwise follow the commercial design and help support volume purchases by the project from OEM in China, and would help homebrewers focus on individually interesting parts of the design without having to resort to making individual design changes in that part of the circuit.

Thank you,

Dave
Re: RF power chain mods and improvements..

 

tim,

I think it would be ok but I have not tested.
Try it and let us know.? I didn't get to that.

Allison
Re: RF power chain mods and improvements..

 

Skip D used printed shcematic and the print is about.01 high.? Oops, it is T9 collector of Q90.

Allison
Re: RF power chain mods and improvements..

 

Thanks Allison..
stupid me i simply did not think before i asked?, i am not young any more and it is very hot in denmark right now
and it was also a lot?easier if someone knew
Vy 73 De OZ1LQB / Claus
Re: RF power chain mods and improvements..

 

William,

Short answer not required.? Though I could as I have I2C displays handy.

The UI will not use a rotary encoder.? There will be an up button and down buttons that
operate as push once briefly you get an increment of frequency change push and
hold it starts stepping like? keyboard key repeat.? So the encoder uses three IO I can
reusefor my needs.

No menu.? There will be a set of buttons one each for U/L(toggle) , VFO A/B(toggle),
SPLIT/On/OFF(toggle), BAND (ring list), and frequency increment (ring list).
Calibrate is an internal function button or serial/USB port as its a one and done.

Since I do not plan to use this radio for CW (I have radios with higher tx power with
less current burn) The unused signals are handy.

Allison
Re: The new uBITX boards are here

 

1n4148 should be OK. Silicon diodes.

Raj

At 07-06-18, you wrote:
Hi, Farhan.What are the values of Diode 14, 15, 16 ? Thanks in advance.
Re: RF power chain mods and improvements..

 

first don't remove r2b..

I measure Voltage across the emitter resistor and then calculate it I=E/R.
I can run a calculator much faster than soldering iron.

The current is highest in Q22 and that will be under 20ma.? Q20 is somewhere about 8-15ma.
the amp has a max output below 1 milliwatt (about .1mW) so it needs only the current required?
to make the device work well.

First try the part and see where the currents land with existing values.

Allison
ND6T AGC question

 

I would like to drive the AGC board with 12V not 5V and assume this involves changing some resistor values. The voltage divider which biases the FET Q2 appears straightforward enough, changing R3 from 100k to around 380k.
The biasing circuit of the amplifier Q1 is more subtle. Changing R2 from 1K to around 2.2K (which seams reasonable) will reduce the slope of the load line, increasing the voltage gain of the amplifier and modify the behavior of the AGC. On the other hand, leaving R1 and R2 unchanged and increasing the voltage from 5 to 12 retains the voltage gain and relocates the quiescent point near the center of the new load line, where it should be. Am I wrong to assume that the only change needed is the value of R3??
?
Comments please. Mike N6CMY?
Re: Noob tx problem #ubitx-help

 

I reversed the orange and purple leads and all is well.? Guess I had the mic wired opposite everyone else.

Thanks Howard and Bo!
Re: The new uBITX boards are here

 

Hi, Farhan.What are the values of Diode 14, 15, 16 ? Thanks in advance.
Re: RF power chain mods and improvements..

 

Allison
do you know how much current Q20, Q21, Q22 draws,the reason for asking is simple,i have a lot of BFR93 and?they only
handle 35ma and 300mw .i would like to avoid remove r2b to mesure it
OZ1LQB / Claus
Re: Removing surface mounted resistor #ubitx

 

¿ªÔÆÌåÓý

For limited work my butane soldering iron (I think it is a Weller) has a hot air tip that works well. ?It is as hot or hotter than my embossing gun (cheap from Hobby Lobby or Joann's Fabric) and works for smd parts.

Dave K8WPE

On Jun 6, 2018, at 10:17 AM, Ralph Mowery <rmowery42@...> wrote:

There are lots of youtube videos on the SMD.? I would not worry about damaging the small parts as they cost almost nothing.

For a one time deal,you can put lots of solder on the part so it just sort of floats off and grab it with some stainless steel tweezers. Use the old standby of 60/40 or 63/37 tin/lead solder and stay away from the lead free stuff.


What I like to use is hot air.? For about $ 60 including shipping you can get one of the hot air rework stations.? While I doubt they would hold up for much usage, I have one and it works fine for hobby usage.? You get the hot air and a soldering pencil with some very small tips that you need.? It also works well on heat shink tubing.

Find some old computer boards that have the SMD on them and practice to you get the hang of it.??

If you plan on doing much smd work, plan on spending about $ 300 to $ 350 to get some equipment.? Look at an Amscope se400z microscope for just under $ 200, the $ 60 hotair rework station, and various? tweezers and a few other things.

On Wed, Jun 6, 2018 at 9:48 AM, Robbie Robertson <robbie.robertson@...> wrote:
I have the R3 board, and have tried to duplicate the anti-pop cct from the R4 schematic (current on a proto board).
The mod works ok, in that there is no 'pop' on transitions between TX and RX, but the CW sidetone is no longer coming through the speaker...

I want to try changing the value of R70 from 10, to 1000 Ohms (as per Rev4), but I've never tried removing a surface mounted component before, and a bit scared of damaging the board/resistor (in case I need to put it back).

Can anyone advise how best to go about this please?

I'm even toying with the idea of cutting the tack on either side so I can bridge the gap with a new value (or feed lines to my proto board for testing of various resistances...


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