Re: RF power chain mods and improvements..
Tim,
The reason to add a stage of amplification like that is so we can reduce
the amplification of pretty much all the other stages.
With reduced gain, they have a much better chance of giving the same gain
at 30mhz as they do at 3.5mhz.
You could try patching this amp in when operating at 30mhz.
Turn RV1 down all the way, then slowly bring it up to get the power you want.
But you had best be ready to measure distortion in your signal before getting on the air with it.
It could well be that Q90 will not work properly with the 10dB increased input signal
and will distort.? Having the amp after Q90? allows you to adjust RV1 down until
any stage after the new amp does not have too strong a signal, strong enough to distort.
I don't think you want this new amp in there at all when operating on the lower frequencies
with an otherwise stock rig.? Too much gain.?
I'm just kibitzing here, have not analyzed the Q90 stage.
You could take the LT-Spice model for the uBitx power amp from the KE7ER directory in the
files section, see what the simulation does when Q90 is driven harder.
Jerry
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On Wed, Jun 6, 2018 at 07:36 pm, Tim Gorman wrote:
Allison,
Jerry,
I have my little mmic board built. Would it be ok to add it before Q90
by removing C80 and inserting the input and output on those pads. Doing
that would allow me to stick the board on top of the relay that is right
beside Q90. It would facilitate testing, experimentation, and
parts changeout if needed. It would also be right beside my 7812
voltage regulator so I would have short power leads.
Will another 10-12db of gain into Q90 be a problem?
tim ab0wr
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uBitx Encoder information needed.
I have 2 items I need info on.
first, does anyone have the specs for the stock encoder for the uBitx?
second, have any of you had to make software changes to get a KY-040 encoder to work properly?
Thanks for your help.
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Its not that hard to replace the Arduino.I have done it on my uBitx and will do it soon on a Bitx40. You can buy a  
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My ubitx was about 1600 to 1700 khz wide.? By changing the 5 capacitors from the crystals in the filter to ground from 100 pf to 82 pf the bandwidth widened out to about 2400 hz for the same reduction in power/audio bandwidth. ??
That may be slightly too wide, but was the next value down from 100 pf that had.? I did try the next value down first, but it was way too wide.? I have been thinking of paralleling the 82 pf ones with about 5 pf but have not done it.?
On Wed, Jun 6, 2018 at 6:11 PM, Eardan <ke4htb@...> wrote: Im currently using KD8CEC skecth and my audio is about 200-1800 and im want to change it to 200-2400 range. i have no problem using the IFS to get it into range but have had no luck changing it in the sketch so that i dont need to use IFS any help to figure this out would be nice
thankyou
KE4HTB
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Re: Removing surface mounted resistor
#ubitx
Another option is to use Chip Quik solder remover. This product is heated with your iron over existing solder joints forming a low temp melting point alloy whi ch stays liquid long enough to lift the part off with tweezers. Then remove the low temp stuff with removal braid.
--
Kevin B. G. Luxford
kbgluxford@...
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Re: RF power chain mods and improvements..
Nice treat,? Allison.
?It takes time and patience with workmanship to implement the mods on the original pcb.
Thanks and regards
sarma /? vu3zmv
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You either have miss wired the
connector, or a bad connector.
On 6/6/2018 10:06 PM, davedt1e@... wrote:
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Just checked the
mic at the plug.? It shows no continuity until I push the the
button...then about 1.6k when I push the button. Have I wired the
mic correctly?
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I'm not sure you can do anything to expand the audio range. That is determined by the 12Mhz filter which has a pretty narrow bandwidth. You could move the bfo to get a 600-2400hz audio but I'm not sure that is what you want. You'll be knocking out a lot of the low-freq audio. tim ab0wr On Wed, 06 Jun 2018 15:11:06 -0700 "Eardan" <ke4htb@...> wrote: Im currently using KD8CEC skecth and my audio is about 200-1800 and
im want to change it to 200-2400 range. i have no problem using the
IFS to get it into range but have had no luck changing it in the
sketch so that i dont need to use IFS any help to figure this out
would be nice thankyou KE4HTB
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Re: RF power chain mods and improvements..
Allison, Jerry, I have my little mmic board built. Would it be ok to add it before Q90 by removing C80 and inserting the input and output on those pads. Doing that would allow me to stick the board on top of the relay that is right beside Q90. It would facilitate testing, experimentation, and parts changeout if needed. It would also be right beside my 7812 voltage regulator so I would have short power leads. Will another 10-12db of gain into Q90 be a problem? tim ab0wr On Wed, 06 Jun 2018 15:42:13 -0700 "ajparent1/KB1GMX" <kb1gmx@...> wrote: One of the factors not reported was the consistency of the gain vs
spur. Simple put the gain and the spur interacted even when I held
the level to the mixer constant. I'd lower the gain and the spur
would get worse as an example.???It varied greatly with supply
voltage as well.
Reason sluggish 3904s (low FT, Maybe Low? HFE).? Remember we are
using a 300mhz device and that is a typical value and can be as low
as 250 (batch and vendor) or much higher.? I changed them out for
BFR106 (Q20, Q21, Q22), Seems the 3904s were not up to the task of
keeping the amp load independent.?
The net result was what others had reported as lower spur production,
in mine it dropped the 10M spur nearly 12db.? So it was either
distortion in the? 45Mhz amp or its ability to be a low output
impedance which should be with emitter follower with the 47ohm making
it look near 50 ohms.? I didn't? try 2n2963A as I didn't have any
left in SMT but I suspect they would have been better.
For now I'm taking a break on output power and addressing other
things.? The power thing stands at 10W at 80m, 7W at 10M with the
spur 46db down.??
I'll list all the changes as my unit stands while I do pop/click and
mod then agc.
For now mods I have in place, I'm not 100% happy but that is what
us experimenters enjoy.? Likely others to come. ;)
?
Replace and reset bias OF Q90 with 2n2369A or better (BFR106),
Set bias for 18ma (r86 2.2K).? Make C81 470pf, and r83 8.2ohms.
Change C82 to 470pf (peaking for 10M).??
T9 is now 9 turns #28 bifilar (one winding was never used).
All the 2n3904s in the predriver and driver replaced with 2n2222A or
better. Hint I mounted them on the underside with very short leads as
it makes the top less crowded.??
Driver amp has 2.7uh SMT choke in series with R86 and that is now
1.6Kohms R87, r88 Both have a 270PF cap in parallel with them.
R911,r96, R941, R942 emitter resistors for driver reduced to 11ohms
(add parallel 22ohm). R92, R95 replaced with 1.5K ohm in series with
2.7uh choke.? (resets bias and adds peaking.)
T10 has one less turn.
T11 reduced by 1 turn.
45mhz IF replace (Q20, Q21, Q22) with BFR106.? Change R23 to 18ohms.
Change R27 to 39 ohms. !2mhz IF amp change R43 to 18 ohma and put
a .1uf in series with 680 ohms across R41.
Replaced Q10 with BFR106 for better receive gain at 20mhz and up.? (I
may change out the two 3409s).
Add LM7806 regulator in handy location to limit voltage to ta2822 to
6V on pin 2. Add 1K resistor from negative side of C77 to ground
(prevents pop when pluging in headphone or speaker)
Add 16K resistor from base o ground of Q70 for better overload
performance.
The one change that really helped the transmitter was going to the
2n2222A (TO18) part. Before that it was 13W on 80 and barely 7 on 40
and less on 20.? After that change alone 40 was near 10W and 20 was
about 8.5W.? This has been tried on another unit that was weak on 40M
and it really helped with no other tricks.
Enough for now.? I plan to spend a few days re-rolling the software
off the V4.3 release for my user interface which will not include
CAT, CW or a rotary encoder.? Without CW mode the sidetone CW-Tone
and CW-KEY pins are usable for general IO by removing R256 and R105.
Allison
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Re: RF power chain mods and improvements..
Allison you referred to T9 being reduced to 9 turns of #28 bifilar did you mistake it with T8 which is bifilar with one winding not used?
toggle quoted message
Show quoted text
On Jun 6, 2018, at 18:42, ajparent1/KB1GMX < kb1gmx@...> wrote: One of the factors not reported was the consistency of the gain vs spur. Simple put
the gain and the spur interacted even when I held the level to the mixer constant.
I'd lower the gain and the spur would get worse as an example.???It varied?
greatly with supply voltage as well.
Reason sluggish 3904s (low FT, Maybe Low? HFE).? Remember we are using a
300mhz device and that is a typical value and can be as low as 250 (batch and
vendor) or much higher.? I changed them out for BFR106 (Q20, Q21, Q22), Seems
the 3904s were not up to the task of keeping the amp load independent.?
The net result was what others had reported as lower spur production, in mine it
dropped the 10M spur nearly 12db.? So it was either distortion in the? 45Mhz amp
or its ability to be a low output impedance which should be with emitter follower
with the 47ohm making it look near 50 ohms.? I didn't? try 2n2963A as I didn't
have any left in SMT but I suspect they would have been better.
For now I'm taking a break on output power and addressing other things.? The
power thing stands at 10W at 80m, 7W at 10M with the spur 46db down.??
I'll list all the changes as my unit stands while I do pop/click and mod then agc.
For now mods I have in place, I'm not 100% happy but that is what
us experimenters enjoy.? Likely others to come. ;)
?
Replace and reset bias OF Q90 with 2n2369A or better (BFR106),
Set bias for 18ma (r86 2.2K).? Make C81 470pf, and r83 8.2ohms.
Change C82 to 470pf (peaking for 10M).??
T9 is now 9 turns #28 bifilar (one winding was never used).
All the 2n3904s in the predriver and driver replaced with 2n2222A or better.
Hint I mounted them on the underside with very short leads as it makes
the top less crowded.??
Driver amp has 2.7uh SMT choke in series with R86 and that is now 1.6Kohms
R87, r88 Both have a 270PF cap in parallel with them.
R911,r96, R941, R942 emitter resistors for driver reduced to 11ohms (add parallel 22ohm).
R92, R95 replaced with 1.5K ohm in series with 2.7uh choke.? (resets bias and adds peaking.)
T10 has one less turn.
T11 reduced by 1 turn.
45mhz IF replace (Q20, Q21, Q22) with BFR106.? Change R23 to 18ohms.? Change R27 to 39 ohms.
!2mhz IF amp change R43 to 18 ohma and put a .1uf in series with 680 ohms across R41.
Replaced Q10 with BFR106 for better receive gain at 20mhz and up.? (I may change out the two 3409s).
Add LM7806 regulator in handy location to limit voltage to ta2822 to 6V on pin 2.
Add 1K resistor from negative side of C77 to ground (prevents pop when pluging in
headphone or speaker)
Add 16K resistor from base o ground of Q70 for better overload performance.
The one change that really helped the transmitter was going to the 2n2222A (TO18) part.
Before that it was 13W on 80 and barely 7 on 40 and less on 20.? After that change alone
40 was near 10W and 20 was about 8.5W.? This has been tried on another unit that
was weak on 40M and it really helped with no other tricks.
Enough for now.? I plan to spend a few days re-rolling the software off the V4.3 release
for my user interface which will not include CAT, CW or a rotary encoder.? Without CW
mode the sidetone CW-Tone and CW-KEY pins are usable for general IO by removing
R256 and R105.
Allison
|
Just checked the mic at the plug.? It shows no continuity until I push the the button...then about 1.6k when I push the button. Have I wired the mic correctly?
|
Thanks for your help.? So I just checked with mic plugged in.? It seems to be shorting the ptt (orange wire) to ground without pushing the button.? Indicating a problem with the mic itself?
|
Re: RF power chain mods and improvements..
I guess i don't understand where you are going with the software... but wouldn't it be easier to convert your display work from the I2C buss? ?Then you have a whole host of pins to work with... freed up from the parallel data lines of the ex-display?
?
Dr.?William J. Schmidt - K9HZ
On Jun 6, 2018, at 11:42 PM, ajparent1/KB1GMX < kb1gmx@...> wrote:
One of the factors not reported was the consistency of the gain vs spur. Simple put
the gain and the spur interacted even when I held the level to the mixer constant.
I'd lower the gain and the spur would get worse as an example.???It varied?
greatly with supply voltage as well.
Reason sluggish 3904s (low FT, Maybe Low? HFE).? Remember we are using a
300mhz device and that is a typical value and can be as low as 250 (batch and
vendor) or much higher.? I changed them out for BFR106 (Q20, Q21, Q22), Seems
the 3904s were not up to the task of keeping the amp load independent.?
The net result was what others had reported as lower spur production, in mine it
dropped the 10M spur nearly 12db.? So it was either distortion in the? 45Mhz amp
or its ability to be a low output impedance which should be with emitter follower
with the 47ohm making it look near 50 ohms.? I didn't? try 2n2963A as I didn't
have any left in SMT but I suspect they would have been better.
For now I'm taking a break on output power and addressing other things.? The
power thing stands at 10W at 80m, 7W at 10M with the spur 46db down.??
I'll list all the changes as my unit stands while I do pop/click and mod then agc.
For now mods I have in place, I'm not 100% happy but that is what
us experimenters enjoy.? Likely others to come. ;)
?
Replace and reset bias OF Q90 with 2n2369A or better (BFR106),
Set bias for 18ma (r86 2.2K).? Make C81 470pf, and r83 8.2ohms.
Change C82 to 470pf (peaking for 10M).??
T9 is now 9 turns #28 bifilar (one winding was never used).
All the 2n3904s in the predriver and driver replaced with 2n2222A or better.
Hint I mounted them on the underside with very short leads as it makes
the top less crowded.??
Driver amp has 2.7uh SMT choke in series with R86 and that is now 1.6Kohms
R87, r88 Both have a 270PF cap in parallel with them.
R911,r96, R941, R942 emitter resistors for driver reduced to 11ohms (add parallel 22ohm).
R92, R95 replaced with 1.5K ohm in series with 2.7uh choke.? (resets bias and adds peaking.)
T10 has one less turn.
T11 reduced by 1 turn.
45mhz IF replace (Q20, Q21, Q22) with BFR106.? Change R23 to 18ohms.? Change R27 to 39 ohms.
!2mhz IF amp change R43 to 18 ohma and put a .1uf in series with 680 ohms across R41.
Replaced Q10 with BFR106 for better receive gain at 20mhz and up.? (I may change out the two 3409s).
Add LM7806 regulator in handy location to limit voltage to ta2822 to 6V on pin 2.
Add 1K resistor from negative side of C77 to ground (prevents pop when pluging in
headphone or speaker)
Add 16K resistor from base o ground of Q70 for better overload performance.
The one change that really helped the transmitter was going to the 2n2222A (TO18) part.
Before that it was 13W on 80 and barely 7 on 40 and less on 20.? After that change alone
40 was near 10W and 20 was about 8.5W.? This has been tried on another unit that
was weak on 40M and it really helped with no other tricks.
Enough for now.? I plan to spend a few days re-rolling the software off the V4.3 release
for my user interface which will not include CAT, CW or a rotary encoder.? Without CW
mode the sidetone CW-Tone and CW-KEY pins are usable for general IO by removing
R256 and R105.
Allison
|
Did you check with an ohmeter with the
unit off at the connector with the mic plugged in that the PTT
switch is working and wired to the right pin, i.e. high impedance
when not pushed, and short to ground when PTT is pushed?
On 6/6/2018 9:05 PM, davedt1e@... wrote:
toggle quoted message
Show quoted text
Still no joy.? I've
checked all the wiring and confirmed connections to jacks with
meter.? I wired up the mic and ptt button as a simple open/close
circuit.? Is this correct?? Pretty frustrated.? Goes straight to
tx when mic is plugged in.? Also verified that ptt button is
working and soldering to the mic element looks good.
Would appreciate any help.? Thanks
|
My friend gave up despite all the help I gave so here's his equipment. I have an unopened uBitx kit (I think version 3) and one of Sunil's cases (grey) plus parts also unopened.? Too many hardware and software changes for me to deal with.? $187.00 plus shipping, PayPal preferred but cleared check accepted.??
?
Tim k5oi
Las Cruces, NM
|
Still no joy.? I've checked all the wiring and confirmed connections to jacks with meter.? I wired up the mic and ptt button as a simple open/close circuit.? Is this correct?? Pretty frustrated.? Goes straight to tx when mic is plugged in.? Also verified that ptt button is working and soldering to the mic element looks good. Would appreciate any help.? Thanks 
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Re: #bitx40 - CW Side Tone Wiring
#bitx40
Allard :?
You raise a good point.?
By using R111 as the injection point for the constant +12V supply to the LM386, I avoid messing with the switching of the power to Q16. So Q16 is off during TX.
The one thing that I did forget is that I actually have an "anti-thump mod" in place that grounds the input to the LM386 via a 2N7000 on PTT closure (see MSG # 25870).
So this combination would explain why I don't hear audio from the mic in the headphones.
?It would be interesting for someone to try this mod on a BITX40?without an anti-thump mod in place to see if their is any appreciable mic audio getting through.?
?The danger when using a speaker on SSB ?is that you might get some audio feedback, which would be bad.?
Cheers
Michael VE3WMB?
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Well, it is a Heater
Control.? Done with a Pic and Assembly done code.? Lots of
nice features.
I have not had a
paycheck in 3 yrs now, so this design was part of a proposal.
This is the nth
change, I keeps going on and on?
A shot in the dark!
Mike, WA6ISP
On 6/6/2018 4:54 PM, William R Maxwell
wrote:
But now you really
should tell us what is, Mike.You have us all curious.
Bill VK7MX
On 7/06/2018 9:30 AM, Michael Hagen
wrote:
A mistake, sorry.?
Went to group when I meant to send it to myself.
Mike, WA6ISP
On 6/6/2018 3:18 PM, Allen Merrell
via Groups.Io wrote:
I am lost here,
what is this.
--
Allen ?Merrell
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
|
Re: Mods and improvements..
If you are like me, Kent, nothing ever works right the first time. ?So, the answer to the last question is probably "no."?
I suggest building the radio into a temporary housing like a cardboard box and trying it out. ?You can always transfer it to a better cabinet and make a better informed set of mods easier in the process.
Should you build it? ?Only you will ever know. ?I'm certainly happy with my results and what I learned in the process.
73,
Tom ?W1EAT
?
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Just an update - I was able to load 4.3 onto the Arduino Nano by using the file Gary sent me. I used a Windows 7 machine to accomplish this. I don't think the Mac is well suited for uploading to the Arduino - at least in my shack.
73, Dennis
W7DRW
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kj6etl
Skip Davis
K9HZ