Date   

Re: Alternate MOSFET finals for BitX40 and others

MVS Sarma
 

Thanks Ajparent. A new point learnt today.
Regards
Sarma vu3zmv

On Wed, 3 Jun 2020, 1:03 am ajparent1/kb1gmx, <kb1gmx@...> wrote:
the parameter Cgs is not that much a factor for example the BLF278 a very nice 300W
VHF device the input CCgs is 480pf!

Its capacitance from gate to drain is a mere 14pf.  That is important as its negative
feedback, and possible gain limiting factor.

In all cases feeding the gate require power and if you can deliver it.
More Cgs means more power required to impress the needed votlage
across the gate to source can do the job.  However long leads on the
mosfet really hurts as  series inductance in the gate to source path
that limits the available power to the gate to source junction.

So if the driver design is weak not enough power or poor impedance
match the power out will be limited and that pretty much regardless
of the device picked.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO


Bitx40 in instrument case is Sold

Marc Pressman <mapn4dr@...>
 

Many thanks for all the interest in the Bitx40.
It is sold.

73,
Marc N4DR


Re: Bitx40 for Sale

mapn4dr@...
 

Ken:
Thanks for the kind words

Marc N4DR 

On Tue, Jun 2, 2020 at 12:51 PM Ken Hansen <ken@...> wrote:
Marc,

Very nice build, good luck with the sale.

Ken, N2VIP

On Jun 2, 2020, at 11:17, Marc Pressman <mapn4dr@...> wrote:


   I have a Bitx 40 in an instrument case assembled and working. Raduino1.27.2 
software.
Asking $100 with free shipping to CONUS.

Marc N4DR
<IMG_2088.JPG>


Re: I need a lynx’s eye for the torus windings.

 

Hi Gerard,

You might want to check the Wiki here for Alison's changes to some of the toroids for more balanced performance. 

https://groups.io/g/BITX20/wiki/7641

73.


Re: Alternate MOSFET finals for BitX40 and others

ajparent1/kb1gmx <kb1gmx@...>
 

the parameter Cgs is not that much a factor for example the BLF278 a very nice 300W
VHF device the input CCgs is 480pf!

Its capacitance from gate to drain is a mere 14pf.  That is important as its negative
feedback, and possible gain limiting factor.

In all cases feeding the gate require power and if you can deliver it.
More Cgs means more power required to impress the needed votlage
across the gate to source can do the job.  However long leads on the
mosfet really hurts as  series inductance in the gate to source path
that limits the available power to the gate to source junction.

So if the driver design is weak not enough power or poor impedance
match the power out will be limited and that pretty much regardless
of the device picked.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO


Re: I need a lynx’s eye for the torus windings.

Gérard <kabupos@...>
 

Hello N5Ib_2,

Thank's for your answer. I 
I understood that crossing the center of the torus counts for one lap. So, in this photo for example, we are at 10 laps.
Have a nice day.


Le mar. 2 juin 2020 à 20:51, n5ib_2 <n5ib@...> a écrit :
Those in the photo are eleven turns.
Each penetration of the center of the toroid counts as a turn.

For example, a wire going in one side and out the other is one turn. It does not have to wrap around.





Re: I need a lynx’s eye for the torus windings.

Jim, N5IB
 

Those in the photo are eleven turns.
Each penetration of the center of the toroid counts as a turn.

For example, a wire going in one side and out the other is one turn. It does not have to wrap around.


Re: CW Filter

R. Tyson
 

Hi Laurent,

Well done and the filter makes a dramatic difference to the uBitX.

I have been really impressed by mine. Another thing I found - the uBitX is very stable.
I had the filter switched to it's narrowest position and was listening to a CW station while messing about with something on the bench. The signal stayed exactly the same for around 10 to 15 minutes with no sign of frequency drift. That also proved the other guy was stable as well.

73's

Reg            G4NFR

  


Re: Bitx40 for Sale

Ken Hansen
 

Marc,

Very nice build, good luck with the sale.

Ken, N2VIP

On Jun 2, 2020, at 11:17, Marc Pressman <mapn4dr@...> wrote:


   I have a Bitx 40 in an instrument case assembled and working. Raduino1.27.2 
software.
Asking $100 with free shipping to CONUS.

Marc N4DR
<IMG_2088.JPG>


I need a lynx’s eye for the torus windings.

Gérard <kabupos@...>
 

Hello to all
May  a user of this forum tell me the number of turns on HF transformers from T1 to T11 on à Ubitx V6. 

it's for my construction. it's noted in the documentation of µbitx V6 that it's 8 to 10 turns. No more précision.
If I look at pictures, it’s more for me 9 turns.
So can you answer me for a basic µbitx V6

You may see also some possibles modifications after for most power:

Besides, when we look at this topics, https://groups.io/g/BITX20/wiki/7641, We realize that we have to remove 8 turns on T8 for example if we make these modifications.
That would mean that T8 is down to one or two turns. Is that possible.
In fact, I’m looking at every possible improvement.

Here, my FT 37 43 transformers remodified to 9 turns (Before other modifications from yours answers) . I have passed my week to turn.
Thank's for your answers.






Bitx40 for Sale

Marc Pressman <mapn4dr@...>
 

   I have a Bitx 40 in an instrument case assembled and working. Raduino1.27.2 
software.
Asking $100 with free shipping to CONUS.

Marc N4DR


Re: Pre driver and driver transistors

roebi@...
 

I'm thinking about these mods as well.

In the wiki for Allison's solution, there is the easy part with just replacing 2n2222's plus Q90 and C81, and then there is the more complicated mod. And then there is the recommended solution from ubitx.net: http://ubitx.net/fix-fix-uneven-tx-output-across-bands/ with the easy part of Allisions solution and a 2nd part with relais get the power to equal levels across the bands. This is probably no the nicest solution, but seems a lot easier than the rest of Allisons mods.

So now the questions:

What output power across the different bands can be expected with just the easy part of Allison mod?

Has anyone here done the easy part plus relais solution?

Are these solutions capable of digital modes without overheating, or is it necessary to somehow reduce power for FT8/WISPR?
As 10W is probably too much for digital modes anyway, the relais solution could easily be extended with an additionals switch and potentiometer for manual power reduction.

Thanks,

Robert


Re: Not getting daily digests

 

Groups.io has been having this problem sporadically for some time (some accounts are fine and other suffer this issue). Mark is looking at it and trying to determine what's causing it. In the meantime, switching to digest mode should resolve this temporarily.
--
Dave Rypma
VE3HTC / VE3DTR


On Mon, Jun 1, 2020 at 03:05 PM, Arv Evans wrote:
Raj
 
Seems the problem is now fixed.  Not sure what happened, but making his 
preference into Full Digest seems to have eliminated the problem.
 
Arv
_._
 

On Sun, May 31, 2020 at 10:09 PM Raj vu2zap <rajendrakumargg@...> wrote:
Arv,

You could check the bounce status of  Keith.. if the mail has bounced a few times and IO will stop further emails.

Raj

At 30/05/2020, you wrote:

>Thanks, Arv.  I was in error.  I did want the daily summary and did recheck and save it to no avail.  I’m still not getting the summary.  I checked spam and junk folders and don’t find any there.  I am a member of the SKCC and two other groups in which I receive their daily summaries with no problem.  So I guess I don’t know why my ISP would block BitX20 and not the others. 
>
>Thanks for your reply.  I had to search for my email to find your reply so sorry for not replying sooner.  At this point, I’m considering cancelling my subscription to the group and then re-subscribing to see if that might work.
>
>73, Keith AGOH


Re: CW Filter

laurent.bury@...
 

Hi Reg,

I just finished today to fit the Sotabeams in my uBitx case.



I used the genuine audio output (yellow wire) of the uBitx, to feed the Sotabeams filter (audio In), connected along with the "V" output of my AGC (https://shop.kit-projects.com/index.php?route=product/product&product_id=101), and the audio output of the filter to the High side of the volume pot.

No RF troubles in the audio, and the filter is VERY efficient in CW narrow mode :)

73s F5FIE.


--
Laurent F5FIE.


Re: Not getting daily digests

Arv Evans
 

Raj

Seems the problem is now fixed.  Not sure what happened, but making his 
preference into Full Digest seems to have eliminated the problem.

Arv
_._


On Sun, May 31, 2020 at 10:09 PM Raj vu2zap <rajendrakumargg@...> wrote:
Arv,

You could check the bounce status of  Keith.. if the mail has bounced a few times and IO will stop further emails.

Raj

At 30/05/2020, you wrote:

>Thanks, Arv.  I was in error.  I did want the daily summary and did recheck and save it to no avail.  I’m still not getting the summary.  I checked spam and junk folders and don’t find any there.  I am a member of the SKCC and two other groups in which I receive their daily summaries with no problem.  So I guess I don’t know why my ISP would block BitX20 and not the others. 
>
>Thanks for your reply.  I had to search for my email to find your reply so sorry for not replying sooner.  At this point, I’m considering cancelling my subscription to the group and then re-subscribing to see if that might work.
>
>73, Keith AGOH





Re: Bitx V6 Modifications

Evan Hand
 

Hiss reduction update

I finished the first go-round with my Amateur Radio Kits case upgrade for my v5 uBitx.  Ran into an audio feedback issue when using the provided 5 watt audio amp.  The cause of the feedback was the excessive gain in the audio sections of the combined ubitx and audio amp.  The gain of the LM386 on the ubitx board is set at 200 for the onboard LM386 (1 uf cap between pins 1 and 8).  I removed pins 1 and 8 (bent them parallel to verify the gain issue) and that set the gain to the default 20 and solved the feedback problem.  Now the "hiss" was back, and the pin 5 to pin 8 bass increase also caused gain issues.  The solution was to go back to the LM386 datasheet and find the proposed solution there:  a 0.33 uf cap in series with 10 K ohms resistor between pins 1 and 5.  This worked for the rig with the amplifier board.

Passing on the learning experience.  Use it as you will.
73
Evan
AC9TU


Re: bitx40 v3 and ubitx v3 for sale

Mervyn Northover <grandadmervyn@...>
 

NOW BOTH SOLD


Re: Alternate MOSFET finals for BitX40 and others

MVS Sarma
 

Better we select by low Cgs so that for multibanders it serves at even 10m babd. 


On Mon, 1 Jun 2020, 5:33 pm Mick, <Mgsebele@...> wrote:
Has anyone considered replacing the irf510 with an irf520? I’ve seen a case of an Irf530 being replaced with an Irf540.
--
 

73
Mick VA3EPM 


Re: Alternate MOSFET finals for BitX40 and others

Mick
 

Has anyone considered replacing the irf510 with an irf520? I’ve seen a case of an Irf530 being replaced with an Irf540.
--
 

73
Mick VA3EPM 


Re: bitx40 v3 and ubitx v3 for sale

Leo
 

I’m in for the Bitx40 if it’s the kit of parts. 

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