Re: ?BitX v4 no SSB output after mods
change the transistor ... it just has a too high bias voltage (to
low sensitivity/gain)
dg9bfc sigi
Am 18.07.2021 um 12:35 schrieb rajesh
huddar:
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Hi Evan,
I have Ver 3.7
The power output on 40m is only 5w and even by
going full on the trimpot, it barely reaches 7w.
So I checked the PA current. As per the user
guide it says with a dummy load it should give atleast 400 to
500 ma after pressing the PTT.
This is in the full clockwise condition of the
PA presets.
But I only get 275ma. Checked R97,98 and C261
and 262. These components are ok as well.
What could?be the problem?
Thanks & Regards?
Rajesh
It is interesting to observe new members of
the group as they learn
more about the BITX series of transceivers.?
Within a reasonable
amount of time these new members are helping
other new members
and are becoming the new old timers.? There
is a magic in Farhan's
BITX invention.? It is the education it
provides through building and
operation,
and it is the continuing education?and
gradual understanding
of how a BITX transceiver really works.? But
it goes
beyond that.?
The group includes members who have built
their expertise through
academics and members who have built
the same knowledge?by
hands-on
and by making mistakes and then correcting them.?
Everybody
helps everybody else with suggestions and
troubleshooting.?
_._
On Sat, Jul 17, 2021, 5:12
PM Don - KM4UDX < dontay155@...>
wrote:
Arv ¡ª. Thank you very much for the info. My days of
pushing more RF out the uBITX door are over. 10-15 watts
do all I need to do.? My 510s and toroids are safe from
¡°enhancements¡±.
?If only I was less of a knucklehead, my FrankenBITX
might even be safe from ¡°repair¡±, but I¡¯ve learned to
count on myself to innovate to minor catastrophe on a
regular basis. Hahah.?
Back to Jonathan ¡ª thank you soooo much for the plots of
power vs mod. You have done great work!! Well done.?
?
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Re: ?BitX v4 no SSB output after mods
Hi Evan,
I have Ver 3.7 The power output on 40m is only 5w and even by going full on the trimpot, it barely reaches 7w.
So I checked the PA current. As per the user guide it says with a dummy load it should give atleast 400 to 500 ma after pressing the PTT. This is in the full clockwise condition of the PA presets.
But I only get 275ma. Checked R97,98 and C261 and 262. These components are ok as well.
What could?be the problem?
Thanks & Regards?
Rajesh
It is interesting to observe new members of the group as they learn
more about the BITX series of transceivers.? Within a reasonable
amount of time these new members are helping other new members
and are becoming the new old timers.? There is a magic in Farhan's
BITX invention.? It is the education it provides through building and
operation, and it is the continuing education?and gradual understanding
of how a BITX transceiver really works.? But it goes beyond that.?
The group includes members who have built their expertise through
academics and members who have built the same knowledge?by
hands-on and by making mistakes and then correcting them.?
Everybody helps everybody else with suggestions and troubleshooting.?
_._
On Sat, Jul 17, 2021, 5:12 PM Don - KM4UDX < dontay155@...> wrote: Arv ¡ª. Thank you very much for the info. My days of pushing more RF out the uBITX door are over. 10-15 watts do all I need to do.? My 510s and toroids are safe from ¡°enhancements¡±.
?If only I was less of a knucklehead, my FrankenBITX might even be safe from ¡°repair¡±, but I¡¯ve learned to count on myself to innovate to minor catastrophe on a regular basis. Hahah.?
Back to Jonathan ¡ª thank you soooo much for the plots of power vs mod. You have done great work!! Well done.?
?
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Hi?
Du?an, I am already on his list but really appreciate the offer. Thanks!
Hi Peter,?
I ordered 2 boards for myself, one as spare, but it's not critical for me so if you really want it and if ¸é²¹³¾¨®²Ô has no spare ones he can send to you, he can redirect one mine to you. If ¸é²¹³¾¨®²Ô?is okay with that, I'm good with it
Regards,
Du?an
|
Hi Peter,?
I ordered 2 boards for myself, one as spare, but it's not critical for me so if you really want it and if ¸é²¹³¾¨®²Ô has no spare ones he can send to you, he can redirect one mine to you. If ¸é²¹³¾¨®²Ô?is okay with that, I'm good with it
Regards,
Du?an
|
Re: ?BitX v4 no SSB output after mods
It is interesting to observe new members of the group as they learn
more about the BITX series of transceivers.? Within a reasonable
amount of time these new members are helping other new members
and are becoming the new old timers.? There is a magic in Farhan's
BITX invention.? It is the education it provides through building and
operation, and it is the continuing education?and gradual understanding
of how a BITX transceiver really works.? But it goes beyond that.?
The group includes members who have built their expertise through
academics and members who have built the same knowledge?by
hands-on and by making mistakes and then correcting them.?
Everybody helps everybody else with suggestions and troubleshooting.?
_._
On Sat, Jul 17, 2021, 5:12 PM Don - KM4UDX < dontay155@...> wrote: Arv ¡ª. Thank you very much for the info. My days of pushing more RF out the uBITX door are over. 10-15 watts do all I need to do.? My 510s and toroids are safe from ¡°enhancements¡±.
?If only I was less of a knucklehead, my FrankenBITX might even be safe from ¡°repair¡±, but I¡¯ve learned to count on myself to innovate to minor catastrophe on a regular basis. Hahah.?
Back to Jonathan ¡ª thank you soooo much for the plots of power vs mod. You have done great work!! Well done.?
?
|
Re: ?BitX v4 no SSB output after mods
I reuse old laptop power adapters @ 19.8v, or 24v (dual 12v + 12v batteries), and they drive the finals direct, and a buck converter makes 12v for the board.?
So heat dissipation is an non-trivial issue. ?I hacked heat sinks from an old cpu, and added a fan, and kept the case sides well ventilated (meaning there aren¡¯t any). ?It worked really well, for a while. Then I pulled defeat from the jaws of victory and parts ¡°evaporated¡± for ¡°no reason at all¡± as my kids say. Hahaha.?
here are a few pics. I now have a fan, and I¡¯ve been told by others, more wise than I, that my larger heat sinks are still too small. That may explain various ignition events. Hahah. ?I put a thermal switch inline with the fan voltage supply ?¡ª the goal was to have it off except when heat was happening. ?The switch pictured closes at 60deg c. Way too high. I use a 35 deg C (95deg f) now. ?
it works well except in the face of stupidity. Hahah ?
?
   
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Re: ?BitX v4 no SSB output after mods
Arv ¡ª. Thank you very much for the info. My days of pushing more RF out the uBITX door are over. 10-15 watts do all I need to do. ?My 510s and toroids are safe from ¡°enhancements¡±.
?If only I was less of a knucklehead, my FrankenBITX might even be safe from ¡°repair¡±, but I¡¯ve learned to count on myself to innovate to minor catastrophe on a regular basis. Hahah.?
Back to Jonathan ¡ª thank you soooo much for the plots of power vs mod. You have done great work!! Well done.?
?
|
Thanks Ramon, I was just being nosey and checking in to see if you had ordered a batch of boards, looking forward to experimenting with one of these.
Gracias!!
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Re: ?BitX v4 no SSB output after mods
Looks like L7 is in the wrong position, needs to be next to the crystal by scraping the enamel from the copper.
Seems you opened the circuit and there is no connection from the crystal to L7 where it is placed.
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Order Status now: 
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Re: ?BitX v4 no SSB output after mods
Don
To the best of my knowledge the toroids that are shipped with the
uBITX are fine for power levels up to 40 or 50 watts.? There are some
who may disagree, but they are not the ones who are designing and
building transceivers.?
Biggest power limitation seems to be the IRF510's, but those will
run around 50 watts in a circuit that is designed for it.? Problem
is the 50 watt factor and a multi-band transceiver seem to be
incompatible.
There are a couple of CB amplifiers that use upwards of 12 IRF510s
in parallel-push-pull, but those are single frequency amplifiers tuned
specifically for that band.? They use huge heat sinks and don't seem
to be very concerned about signal purity.
Allison (she lurks around here sometimes) has run multiple IRF510s
at 50 watts on 6 meters , so it is possible.
Point is that the gain from 10 watts to 20 watts is difficult to obtain in
a uBITX, and requires that the antenna be well tuned and stable at
that tuning and frequency.
There are other ways to increase power out on a uBITX.? This usually
involves changing the finals to RF transistors ($$ each) and adding
another driver stage ahead of the finals.? There is also the option of
adding an outboard amplifier, as some have attempted.? Outboard
amplifiers can also be staged with pairs of amplifiers driving bigger
amplifiers, with pairs of these driving even bigger amplifiers.? That sort
of defeats the idea of QRP power, QRP costs, and QRP problems
when things go wrong.
Arv _._
On Sat, Jul 17, 2021 at 11:23 AM Don - KM4UDX < dontay155@...> wrote: Arv - so on my own, locked in the embrace of my own inexperience and lack of training, I had a slowly dawning revelation ¡ª improving my antenna system (transformers, chokes, feed lines, radiating elements, etc.) produced more better net benefits than torching my IFR510s (yet again).?
So I can humbly confirm from direct hands-on repeated experience¡get ready¡you are right.?
Some hard earned knowledge is more precious than ?academic insight. Especially for the slow learners. Hahah
And when I started on my uBITX radio journey, I watch my signal in horror as I experimented. Turns out the key to a clean waveform is a reduced drive level. Or as my Dad used to tell me repeatedly, ¡°turn that darn thing down!¡±
But - my question stands, at higher power levels, is there any benefit from upgrading any of the various post final toroids??
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Since my last Specan post, I've changed the mixer oscillator sources to an Si5351 board connected with coax cables to the mixer modules.? CLK 2 drives the first mixer and CLK 1 the second.? I'm presently using the Etherkit library with CLK2 assigned to PLLA and CLK1 assigned to PLLB.? Both outputs are set to 8 mA drive.? There is a 6 dB pad at each mixer input as in the original design. Unfortunately there are now many spurs which presumably are caused by my Si5351 arrangement.? The first sceen shot is with a single-tone 7029 kHz input.? With no input, this range is flat.? The second screen shot is with no input, showing a multitude of spurs. I would appreciate any comments about where to go from here.? Performance was much better with the Si570 and analog 100 MHz oscillator, but it seems like the Si5351 should be possible.? By the way, the noise floor and IIP are unchanged from the earlier results since I haven't done anything to the gain architecture yet. Regards, -- David KV4FP  
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Re: ?BitX v4 no SSB output after mods
Arv - so on my own, locked in the embrace of my own inexperience and lack of training, I had a slowly dawning revelation ¡ª improving my antenna system (transformers, chokes, feed lines, radiating elements, etc.) produced more better net benefits than torching my IFR510s (yet again).?
So I can humbly confirm from direct hands-on repeated experience¡get ready¡you are right.?
Some hard earned knowledge is more precious than ?academic insight. Especially for the slow learners. Hahah
And when I started on my uBITX radio journey, I watch my signal in horror as I experimented. Turns out the key to a clean waveform is a reduced drive level. Or as my Dad used to tell me repeatedly, ¡°turn that darn thing down!¡±
But - my question stands, at higher power levels, is there any benefit from upgrading any of the various post final toroids??
|
Hi Shane,
Yes, approximately. I have your email address and when the PCBs arrive I will contact you for details: postal address, payment, etc.
¸é²¹³¾¨®²Ô
|
Hi, Peter,
Yes, the order has already been placed and is in production. Any suggestion? you need something?
¸é²¹³¾¨®²Ô
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Re: ?BitX v4 no SSB output after mods
If anyone's interested in my power readings, I'm attaching a plot.? Can send more detail if interested.
-- Jonathan, KD5CFX
Don KM4UDX
My suggestion would be to not get too excited about over power beyond the
design specification.? Take a look at the datasheet for IRF510 devices to see
where the best position on the load-line is for each feed voltage, and stay
within that range.? Operating at over-voltage stresses some components and
causes splatter from spurious signals.? Over-driving any transmitter is not
a good idea.? Higher power within the absolute limits of the uBITX brings the
finals into flat-topping mode where one or the other, or both, sides of the
modulation are clipped when the signal reaches positive voltage limit or reaches ground.? After all you will get less than one S-unit increase in signal at the
other end, no matter how much you overdrive the uBITX.?
Overdriving your transmitter does nothing to help you receive better.? It is
much more productive to work on antenna effectiveness and help your
signal on both receive and transmit side of things.
Arv _._
On Sat, Jul 17, 2021 at 8:44 AM Don - KM4UDX < dontay155@...> wrote: Hello! Given Jonathan¡¯s mods making 26w (under some conditions), are there any toroid ?heat management issues at >20 watts through the various LPFs and output transformer?
And if he were to drive the finals with (say) 24v, then the finals might produce >30watts? Wow.
I¡¯ve run into heat dissipation ¡°issues¡± at >10watts ¡ª so I¡¯ve called in the mega heat sinks, fans, liquid nitrogen cooling, etc.? At these levels generally, the worry about spontaneous Chernobyl events ?adds an element of excitement. And I discovered that at certain power levels, you can melt the little three pin power connector on the board.? Fortunately, any servo connector will fit the board jack, you do lose the polarity feature of the proper connector, which gives you another chance for excitement.?
Jonathan ¡ª what is your approach to heat management at your prodigious power levels?
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Re: ?BitX v4 no SSB output after mods
Don KM4UDX
My suggestion would be to not get too excited about over power beyond the
design specification.? Take a look at the datasheet for IRF510 devices to see
where the best position on the load-line is for each feed voltage, and stay
within that range.? Operating at over-voltage stresses some components and
causes splatter from spurious signals.? Over-driving any transmitter is not
a good idea.? Higher power within the absolute limits of the uBITX brings the
finals into flat-topping mode where one or the other, or both, sides of the
modulation are clipped when the signal reaches positive voltage limit or reaches ground.? After all you will get less than one S-unit increase in signal at the
other end, no matter how much you overdrive the uBITX.?
Overdriving your transmitter does nothing to help you receive better.? It is
much more productive to work on antenna effectiveness and help your
signal on both receive and transmit side of things.
Arv _._
On Sat, Jul 17, 2021 at 8:44 AM Don - KM4UDX < dontay155@...> wrote: Hello! Given Jonathan¡¯s mods making 26w (under some conditions), are there any toroid ?heat management issues at >20 watts through the various LPFs and output transformer?
And if he were to drive the finals with (say) 24v, then the finals might produce >30watts? Wow.
I¡¯ve run into heat dissipation ¡°issues¡± at >10watts ¡ª so I¡¯ve called in the mega heat sinks, fans, liquid nitrogen cooling, etc.? At these levels generally, the worry about spontaneous Chernobyl events ?adds an element of excitement. And I discovered that at certain power levels, you can melt the little three pin power connector on the board.? Fortunately, any servo connector will fit the board jack, you do lose the polarity feature of the proper connector, which gives you another chance for excitement.?
Jonathan ¡ª what is your approach to heat management at your prodigious power levels?
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Re: ?BitX v4 no SSB output after mods
Oh, wow!? That's the picture I was using for reference, but I was working in the middle of the night and must've missed it in my sleepy haze.? I'll fix that in the next day or so and report back...? Thanks, Raj!
-- Jonathan, KD5CFX
Looks like what I used. Should be no problem.
A picture is worth a 1000 word.. You soldered L7 in the wrong
place...
Now fix it and test and open a bud and drink it on my behalf!
Cheers
Raj
At 17/07/2021, you wrote:
Thanks, Raj.?? I'll put the
original toroids back and report back, but today is YL's birthday, so it
might not be until tomorrow...
The inductors I used are these:
Attached is a picture I took after installing them.?? I suppose it's
also possible I damaged them while soldering them in¡ªas I said, this was
my first time doing SMDD soldering.
--
Jonathan
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Re: ?BitX v4 no SSB output after mods
Looks like what I used. Should be no problem.
A picture is worth a 1000 word.. You soldered L7 in the wrong
place...
Now fix it and test and open a bud and drink it on my behalf!
Cheers
Raj
At 17/07/2021, you wrote:
toggle quoted message
Show quoted text
Thanks, Raj.?? I'll put the
original toroids back and report back, but today is YL's birthday, so it
might not be until tomorrow...
The inductors I used are these:
Attached is a picture I took after installing them.?? I suppose it's
also possible I damaged them while soldering them in¡ªas I said, this was
my first time doing SMDD soldering.
--
Jonathan
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Re: ?BitX v4 no SSB output after mods
Thanks, Don.
Heat dissipation is an important issue that I haven't gotten to yet with these mods.? I undertook the mods related to power with the idea that it would level out power across the bands¡ªi.e., give me a bit of boost on the bands that weren't giving me even 5W.? I wasn't expecting anything close to 26W!? I think one solution might just be for me to dial it down when I use those bands.
Heat dissipation is an issue I have thought about though.? Fairly soon after I first put together my ?BitX, I screwed the L7805 (for the raduino) to the case¡ªwhich is just a holiday tin but dissipates the heat much better than nothing.? I have a few heatsinks in my junk bin that I've been thinking of throwing on it too.
I'll keep an eye on the power connector, and if I notice any issues I can throw on some powerpoles¡ªsomething I've had in mind since the beginning but never really saw a need for.? And that would of course avoid the polarity confusion problem.? (I have the suggested reverse-polarity-protecting diode soldered to the back of the current power connector.? I'd want to keep that of course anyway).
As for the finals, I don't really have the experience to protect them better than the stock heatsinks.? So I'm open to suggestions other than dialing the power back.? Anything out there anyone has done before?
-- Jonathan
On Sat, Jul 17, 2021 at 10:44 AM Don - KM4UDX < dontay155@...> wrote: Hello! Given Jonathan¡¯s mods making 26w (under some conditions), are there any toroid ?heat management issues at >20 watts through the various LPFs and output transformer?
And if he were to drive the finals with (say) 24v, then the finals might produce >30watts? Wow.
I¡¯ve run into heat dissipation ¡°issues¡± at >10watts ¡ª so I¡¯ve called in the mega heat sinks, fans, liquid nitrogen cooling, etc.? At these levels generally, the worry about spontaneous Chernobyl events ?adds an element of excitement. And I discovered that at certain power levels, you can melt the little three pin power connector on the board.? Fortunately, any servo connector will fit the board jack, you do lose the polarity feature of the proper connector, which gives you another chance for excitement.?
Jonathan ¡ª what is your approach to heat management at your prodigious power levels?
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rajesh huddar
Raj vu2zap