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Re: Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?

 

The same schematic works for both. I will send you the LC filter details if you need them. The 45 mhz filters are regularly available on ebay.
- f

On 5 Jun 2018 12:02 am, "David Feldman via Groups.Io" <wb0gaz=[email protected]> wrote:
This posting contains two questions:

I am building a homebrew version of ubitx (on PCB layout I created myself). PCB was manufactured a year ago, but did not start bringing up circuit at that time.

Since about 2 weeks ago, I have been bringing up the receive path first (along with necessary microcontroller and synthesizer stages), one stage at a time, beginning with the loudspeaker, and so far having good results and fun experience.

I realize now (that I am at the 45 MHz IF filter, heading towards the first mixer) that I did not save schematic I used to create PCB, and v3 schematic (more recent) includes a part (the 45 MHz crystal filter) I did not find in the version I based my PCB layout on. I understand the benefit of the filter, however, I wish to continue progress on my PCB based on older design, as I will gather changes (including use of the newer IF filter design) for a future PCB rev.

My PCB layout assumed multi-pole LC filter from the schematic I had available at the time (original or maybe v2, but not v3 or later). In this version, the 45M15(A? B? F?) filter was not included, and it is not present on my PCB layout.

So, I have two questions:

1. What is URL or other way to find version of ubitx based on LC filter in 45 MHz path?

2. Where is current source for the 45M15 (A? B? F?) filter used in V3 and later designs? I did not find it in search on US distributors nor on ebay; I understand these should be low cost part with good availability, so I think I am not looking in right place?

Thank you, and this is very enjoyable project!

73 Dave WB0GAZ wb0gaz@...
Building homebrew ubitx: Need pre-v3 schematic PDF. Also, source for 45M15 (45 MHz IF) filter?

 

This posting contains two questions:

I am building a homebrew version of ubitx (on PCB layout I created myself). PCB was manufactured a year ago, but did not start bringing up circuit at that time.

Since about 2 weeks ago, I have been bringing up the receive path first (along with necessary microcontroller and synthesizer stages), one stage at a time, beginning with the loudspeaker, and so far having good results and fun experience.

I realize now (that I am at the 45 MHz IF filter, heading towards the first mixer) that I did not save schematic I used to create PCB, and v3 schematic (more recent) includes a part (the 45 MHz crystal filter) I did not find in the version I based my PCB layout on. I understand the benefit of the filter, however, I wish to continue progress on my PCB based on older design, as I will gather changes (including use of the newer IF filter design) for a future PCB rev.

My PCB layout assumed multi-pole LC filter from the schematic I had available at the time (original or maybe v2, but not v3 or later). In this version, the 45M15(A? B? F?) filter was not included, and it is not present on my PCB layout.

So, I have two questions:

1. What is URL or other way to find version of ubitx based on LC filter in 45 MHz path?

2. Where is current source for the 45M15 (A? B? F?) filter used in V3 and later designs? I did not find it in search on US distributors nor on ebay; I understand these should be low cost part with good availability, so I think I am not looking in right place?

Thank you, and this is very enjoyable project!

73 Dave WB0GAZ wb0gaz@...
Re: Correct levels from computer to uBitx in digimodes

Joe Puma
 

¿ªÔÆÌåÓý

When I hooked my bitx40 to my computer I adjusted audio coming out of the computer ?using the volume in computer mixer and monitoring on another radio. For wsjtx I used the waterfall as a visual aid and the radios volume knob to adjust audio into computer.?

This worked well. There is room to play but looking how other applications join a radio with a computer like when making a AllStar node and wiring up speaker and Mic to a computer people put resistors in place to bring the levels down. Like 68k ohms on the radio audio out. Taken before the volume pot so the pot is not controlling the volume. And 10k ohms on the Mic in on radio.?

Here¡¯s the example I am talking about.?

image1.jpeg

What I found that might be more useful instead of worrying about signal levels is hooking the radio up so it¡¯s not electrically connected by using some 1:1 transformers. I found that with using my 100w radio and long audio wires your setup might be susceptible to RF getting in the wires. ?I have an issue on 40 meters with RF getting in my audio if I use my powered mic or long extension wires on my Mic cable. Ferrite beads don¡¯t seem to solve the problems.?

Joe
Kd2nfc?



On Jun 4, 2018, at 10:02 AM, Jan Brink <janbrink@...> wrote:

How does one determine the correct output level from computer to mic in on the uBitx for digimodes like FT8 JT65 PSK etc.? On my FT817 / 897 I watch ALC level. How to do this on the uBitx? ?

Jan
PD0JBZ
Re: Github's future?

 

Agreed, not good.? Anyone aware of an alternate platform for sharing code?
Re: Nextion Display

 

Jack
Thanks for the reply, LOL, I have the book and I need to dig it out and get back into it again. The work you and AL did is fantastic. I just hope to get a similar result with less options on a smaller display. The filter part I am just not going to try programming that I am going to cheat and use a Sotabeam adjustable that I have this will cure filter and audio amp all in one package but just won't ?be on the screen.
73's ?kn4ud ?
--
Allen ?Merrell
ubitx for sale

Joe Parisella
 

New ubitx package selling due time constraints this is the newer socketed version it has been opened to verify all components are present.
Included is a Excellway Desk?Project Case / Handle, 10' roll of EMI conductive 2" copper foil tape for shielding.
I'm selling at my cost $130 plus 15.00 shipping to USA only.?

tnx joe
Re: Github's future?

 

Nothing good, for the consumer, has EVER come from a Microsoft acquisition!
Re: RF power chain mods and improvements..

 

Howard on 28.4 mhz how much power are you getting???

It must be done in SSB MODE.

If you not driving it as hard as you would to get 10+W at 80m then?
it should be 1-2W.? It will be down.

My test I use a audio generator to get 5, 10 and full power at 80m then switch?
to 28.4 (VFO b).? For the base uBitx 5W on 80 is maybe a fraction of a watt
on 10 (barely moves the bird WM using a 25W HF slug). For mine at 13V 80M
Hits 13W and the 10M power is about 2W at that 2W?output the spur is not
-60DBc (about -50dbc as its already creeping up)

If you push the audio harder to get more the spur grows.? But we know the
power chain on 10M is weak so if you on 10M you push or accept 1.7W
(least for mins when stock).? In mine that wa with RV1 maxed out and
no mods.? ?Push the audio?and you get to maybe 4-5W and the spur
is actually near .005W or -30dBc.? At -60DBc would have that 1000
times less or? .005 milliwatts or 5 microwatts.??

The filters for 80 though 17M are effective enough to to remove the
spur as it falls between 3 and 27mhz.? AS you go up the spur
frequency goes down.?

The corner case is in the 21mhz and up range?as the filters there
cut off around 33-35mhz so a spur under?30 mhz will go right though
attenuated and the amp is obliged to deliver it. We also know
the amp at say 16.6mhz has more gain that at 28 the spur is
bigger there at the output and we can't blame the amp for
that because if it did have the same gain at 28 as at 80m the
spur would be 10-11db bigger at the output at all drive levels.

Note of you looking at a very specific frequency you may be off
as the spur is tuneable. so when I say xxmhz I'm rounding to the?
nearest whole number.? For 28.4 its about 16.6ish mhz.

I've attached a .xls run fr a simple spur table.? Simple as it does not include
higher order input like F through 3F for example.? This is just first order and
I don't add calculations for expected level on the resulting frequency.
Plug in the umber to spurtune and its much more... interesting.

Allison

spur_ubitx.xls
spur_ubitx.xls

Re: RF power chain mods and improvements..

 

Using a HP 8924c in the SA mode I do not seem to be seeing any of the spurs down to at least?
- 50 dbm.? That is by feeding in a 1000 hz tone to the mic input and adjusting the audio level to maximum output and cutting it back to where the power just falls off.

However I do see the carrier (that is supposed to be suppressed) of about -5 to 0 dbm.? That is with the modifications and RD16HHF1 outputs for a power of about 8 watts on 28 MHz.


On Mon, Jun 4, 2018 at 11:37 AM, Arv Evans <arvid.evans@...> wrote:
The uBITX does actually work on 15M, 12M, and 10M (and yes it does work on 11M as
evidenced by the number of CB'ers who have purchased it).? Power output is much lower
on the higher bands, but is still enough to make QRP contacts.? Just do not try to increase
power output on upper bands by adding microphone gain.? Too much microphone audio
will cause spurs, distortion, and QRM.?

Arv? K7HKL
Re: Correct levels from computer to uBitx in digimodes

 

The DVB-t dongles can be very useful, but only have an 8bit ADC.
So absolute best.they could possibly do at 6dB per bit is 48dB of dynamic range.?
Likely a fair bit worse.

To measure the spur in dB down from the main signal, you would first filter out?
the main signal from the spur, and measure the strength of the spur using the dongle.
Then look at the main signal without that filter, using a step attenuator to bring
it down to the same level as the spur.? The dB below carrier is how many?
switches on the step attenuator you had to flip to get the same reading.

But you can't look at the carrier and spur simultaneously because these dongles
don't have enough dynamic range.

Kees has a nice step attenuator, about 1/3 of the way down this webpage:
? ??

I would say that the DVB-t dongles are just like an extremely crummy spectrum analyzer.
For this HF transceiver, you will need one with a down converter so you can?
see stuff below 30mhz.

Jerry


Mon, Jun 4, 2018 at 09:46 am, ajparent1/KB1GMX wrote:

most of those 90$ digital scopes run out of gas below 1mhz.? THey are good for audio.

A O'Scope is not the best too either as its hard to see even significant distortion.

Actually those USB 25-ghz DVB-t with up convertes let you see just like a?
spectrum analyser.

Allison
Re: #ubitx-help #ubitx-help

 

I feel a little stupid (again). I just realised that there are a lot more transistors? than I first thought. At my time there were no such small transistors. Yes, I measured only the RX ones. I guess I will have some problems getting back on the air again..
Re: Correct levels from computer to uBitx in digimodes

 

most of those 90$ digital scopes run out of gas below 1mhz.? THey are good for audio.

A O'Scope is not the best too either as its hard to see even significant distortion.

Actually those USB 25-ghz DVB-t with up convertes let you see just like a?
spectrum analyser.

Allison
Re: The new uBITX boards are here

 

I also found a 50 ohm version of the Visaton that Mouser carries, so there are 8, 16, and 50 ohm versions of this water resistant speaker.? No 32 ohm version, but if 16 or 50 would work I bet this would be a good sounding speaker for SSB voice on this radio.
Re: RF power chain mods and improvements..

 

Also worth noting:

The stock firmware shuts down the bfo and local oscillator to the second mixer
when transmitting CW.? So all RF on the uBitx main board is at the operating frequency.?

Forks of the code should take care to do the same.
This will avoid any unexpected products, also?avoids having mike audio sneak through


On Mon, Jun 4, 2018 at 09:25 am, ajparent1/KB1GMX wrote:
A reminder:

* Generating CW
?* The CW is cleanly generated by unbalancing the front-end mixer
?* and putting the local oscillator directly at the CW transmit frequency.
?* The sidetone, generated by the Arduino is injected into the volume control
?*/

Straight from the source code.? CW TX is not prone to the SPUR issue as it is a clean
signal at the operating frequency with no mixing.? We still have to have low pass
filters to remove harmonics but thats easy and works.

SSB we involve two IFs two FIlters and three Mixers.? Much more going on and?
with far more complex interactions.

Allison
Re: Github's future?

 

This can't be good:-(

Joel
N6ALT
Re: RF power chain mods and improvements..

 

¿ªÔÆÌåÓý

Arv:
I just got an explanation from Allison, which I will confirm later. I measured the spurs in CW which I thought was a side tone, but isn't. I need to retest with actual audio.

Howard

On 6/4/2018 12:21 PM, Arv Evans wrote:

Howard

I'm seeing about the same.

Arv
_._


On Mon, Jun 4, 2018 at 10:18 AM Howard Fidel <sonic1@...> wrote:
Arv:
When properly driven, I see the spurs almost at -60dB.

Howard
On 6/4/2018 11:37 AM, Arv Evans wrote:
The uBITX does actually work on 15M, 12M, and 10M (and yes it does work on 11M as
evidenced by the number of CB'ers who have purchased it).? Power output is much lower
on the higher bands, but is still enough to make QRP contacts.? Just do not try to increase
power output on upper bands by adding microphone gain.? Too much microphone audio
will cause spurs, distortion, and QRM.?

Arv? K7HKL
_._


On Sun, Jun 3, 2018 at 9:01 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
To keep the price down, I think hfsignals may as well continue to use the 45mhz filter.
Perhaps claim 80m through 17m, beyond that is experimental, disable 15m,12m, and 10m
in the stock firmware.? Different transistors for more consistent gain should be considered.


However, if we can instrument drive level into the mixers, sounds like we may be able to have
a clean signal on up to 30mhz.? ?Perhaps replace transistors to get consistent gain through the 45mhz IF
and the Q90 stage, then monitor the top of RV1 with a diode RF probe into a Nano analog pin.

Better yet, add another 10dB of gain after the mixers so the IRF510's show trouble (much more obvious)
long before the mixers do.? So maybe add an extra gain stage between Q90 and RV1,
existing rigs could easily patch this in with an MMIC.?


If we do decide to go to 70mhz and beyond for that first IF, there are viable filters available.

In this post:??/g/BITX20/message/33203
Farhan explains that the 45mhz filter must be narrow enough to reject signals 2 mhz away from center.

Here's the filters on Mouser that are between 70 and 90 mhz, and have a bandwidth of less than 4mhz:
? ??

The PX1002 from Murata looks good to me, center frequency of 86.85mhz.
25khz wide, 3dB insertion loss, over 60dB of rejection at 1mhz out,
datasheet shows how to use it in 50 ohm environment.
Not exactly cheap at $12 single unit, $6 if buying hundreds from Mouser.
The similar PX1004 at 82.2mhz is harder to get, especially in low quantities,
but might be preferred as it allows a lower vfo frequency.?

To operate at 30mhz with an 86.85mhz first IF, the vfo should be 86.85+30 = 116.85mhz.
The Si5351's internal vco is spec'd to a max of 900mhz, and our fractional output dividers can divide down
to a minimum of 8.0, so 900/8=112.5mhz max using the current si5351bx routines with the vco moved to 900mhz.
Hans, G0UPL, has found that the vco can be pressed to go much higher, beyond 1100mhz,
so we could just cheat on that, perhaps 935mhz for the vco giving 935/8 = 116.875mhz max.
I'd try that first.
The other possibility is to use the second Si5351 internal vco with fractional pll feedback and an
integer output divider on clk1, giving fine grained frequency control up to 200mhz (290mhz, according to Hans).
This second method would roughly double the size of the si5351bx routines, but that's not a major hit.
The other two si5351 outputs would continue to use the first vco, and be restricted to 112.5mhz max.

If using the equations of post?/g/BITX20/message/44278
the only needed change to the uBitx code outside the Si5351bx routines would be to change this
uint32_t? f45c? = 44995000;? ? ?// center of 45mhz filter
? to this:
uint32_t? f45c? = 86850000;? ? ?// center of 87mhz filter

The filter and 50 ohm matching networks could be on a very small PC board
glued to the back of the uBitx main board.
This daughterboard could include a new BiDi amp with appropriate transistors.
If the uBitx mixers are problematic at 86.85mhz, then perhaps a couple ADE-1's also,
replacing everything from T2 to T4 inclusive.? Parts cost of around $10 if building hundreds,
$15 bucks if adding the two ADE-1's.?

Then everybody will get fixated on making the uBitx work on 6 meters
and we get to do this all over again.

Jerry, KE7ER

?
On Sun, Jun 3, 2018 at 03:44 pm, ajparent1/KB1GMX wrote:
Its not a drop in.? The filter would likely be hard to find and costly or for a one off salvage from?
an old junker commercial radio.?

I think Kenwood radios used a 63mhz filter or maybe ICOM.? so lets do a thought
experiment on what needs to be done.

The filter would need to be matched and like data for it will require experimental testing.
The T30-2 toroids could be reused and rewould and the cap for the L-networks changed
as needed.? The entire string of 3904s [all 6 of them] in the 45mhz section would have
to be some thing like 2n2369, or better BFR106s.?

Then the firmware has to be revised as the first lo needs to be higher to start maybe
65mhz and go up from there.??

So yes it can be done.? I don't have such a part so thats ruled out.? So for a one off
maybe, doesn't help everyone though. and even if the filter was not too expensive?
thats a lot of SMT and through hole work plus a new firmware.? At the production
level it could add significant cost and interrupt the product flow as you have all the
material in place and likely paid for.

Right now the most feasible option is bandpass filters and switching.? Cost wise the
parts are cheap is SMT inductors are used.? The trick there is drop in and play no
manufacturing tuning.

Allison
Re: Nextion Display

Bo Barry
 

I struggled initially and was overwhelmed ?with one and almost gave up.
Yesterday I spent the whole day with it.
Rather than spill my findings and problems I would like to encourage "everyone" to have the patience and ambition to tackle it.

Google for youTubes, look at all of them. Some of them are lousy, some will be WAY over your head, but there are some gems out there.

There are several ways of programming and using them,fortunately.

Do like I found and use the P&M method (plagurize ? & modify) ?until you can do one from scratch. There are several from scratch demos.

Now to find another spare day to continue. Retirement is a full time job tho. ?73, Bo W4GHV since '54
Re: RF power chain mods and improvements..

 

A reminder:

* Generating CW
?* The CW is cleanly generated by unbalancing the front-end mixer
?* and putting the local oscillator directly at the CW transmit frequency.
?* The sidetone, generated by the Arduino is injected into the volume control
?*/

Straight from the source code.? CW TX is not prone to the SPUR issue as it is a clean
signal at the operating frequency with no mixing.? We still have to have low pass
filters to remove harmonics but thats easy and works.

SSB we involve two IFs two FIlters and three Mixers.? Much more going on and?
with far more complex interactions.

Allison
Re: The new uBITX boards are here

 

I ordered a kit a few weeks ago and think I will be receiving the board with the updated discreet audio amp.? Somewhere I thought I saw that a 32 ohm speaker would be the best fit for this amp, but can't find this post anymore.? What is the best impedance and what is the approximate power out??

I found a small mylar speaker at Mouser that is 150 - 20K, but only 1/5 of a watt, 32 ohms.? Another speaker I found is a bit larger at another vendor, but is 16 ohms.? it is? 2 inches, and handles 2 watts, 180-17K so should be a bit better if this power amp puts out a watt or so.?

I can't seem to find the speaker that looks best for this "on paper" yet, just wondering about the new audio amp's requirements.
Re: RF power chain mods and improvements..

 

Howard

I'm seeing about the same.

Arv
_._


On Mon, Jun 4, 2018 at 10:18 AM Howard Fidel <sonic1@...> wrote:
Arv:
When properly driven, I see the spurs almost at -60dB.

Howard
On 6/4/2018 11:37 AM, Arv Evans wrote:
The uBITX does actually work on 15M, 12M, and 10M (and yes it does work on 11M as
evidenced by the number of CB'ers who have purchased it).? Power output is much lower
on the higher bands, but is still enough to make QRP contacts.? Just do not try to increase
power output on upper bands by adding microphone gain.? Too much microphone audio
will cause spurs, distortion, and QRM.?

Arv? K7HKL
_._


On Sun, Jun 3, 2018 at 9:01 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote:
To keep the price down, I think hfsignals may as well continue to use the 45mhz filter.
Perhaps claim 80m through 17m, beyond that is experimental, disable 15m,12m, and 10m
in the stock firmware.? Different transistors for more consistent gain should be considered.


However, if we can instrument drive level into the mixers, sounds like we may be able to have
a clean signal on up to 30mhz.? ?Perhaps replace transistors to get consistent gain through the 45mhz IF
and the Q90 stage, then monitor the top of RV1 with a diode RF probe into a Nano analog pin.

Better yet, add another 10dB of gain after the mixers so the IRF510's show trouble (much more obvious)
long before the mixers do.? So maybe add an extra gain stage between Q90 and RV1,
existing rigs could easily patch this in with an MMIC.?


If we do decide to go to 70mhz and beyond for that first IF, there are viable filters available.

In this post:??/g/BITX20/message/33203
Farhan explains that the 45mhz filter must be narrow enough to reject signals 2 mhz away from center.

Here's the filters on Mouser that are between 70 and 90 mhz, and have a bandwidth of less than 4mhz:
? ??

The PX1002 from Murata looks good to me, center frequency of 86.85mhz.
25khz wide, 3dB insertion loss, over 60dB of rejection at 1mhz out,
datasheet shows how to use it in 50 ohm environment.
Not exactly cheap at $12 single unit, $6 if buying hundreds from Mouser.
The similar PX1004 at 82.2mhz is harder to get, especially in low quantities,
but might be preferred as it allows a lower vfo frequency.?

To operate at 30mhz with an 86.85mhz first IF, the vfo should be 86.85+30 = 116.85mhz.
The Si5351's internal vco is spec'd to a max of 900mhz, and our fractional output dividers can divide down
to a minimum of 8.0, so 900/8=112.5mhz max using the current si5351bx routines with the vco moved to 900mhz.
Hans, G0UPL, has found that the vco can be pressed to go much higher, beyond 1100mhz,
so we could just cheat on that, perhaps 935mhz for the vco giving 935/8 = 116.875mhz max.
I'd try that first.
The other possibility is to use the second Si5351 internal vco with fractional pll feedback and an
integer output divider on clk1, giving fine grained frequency control up to 200mhz (290mhz, according to Hans).
This second method would roughly double the size of the si5351bx routines, but that's not a major hit.
The other two si5351 outputs would continue to use the first vco, and be restricted to 112.5mhz max.

If using the equations of post?/g/BITX20/message/44278
the only needed change to the uBitx code outside the Si5351bx routines would be to change this
uint32_t? f45c? = 44995000;? ? ?// center of 45mhz filter
? to this:
uint32_t? f45c? = 86850000;? ? ?// center of 87mhz filter

The filter and 50 ohm matching networks could be on a very small PC board
glued to the back of the uBitx main board.
This daughterboard could include a new BiDi amp with appropriate transistors.
If the uBitx mixers are problematic at 86.85mhz, then perhaps a couple ADE-1's also,
replacing everything from T2 to T4 inclusive.? Parts cost of around $10 if building hundreds,
$15 bucks if adding the two ADE-1's.?

Then everybody will get fixated on making the uBitx work on 6 meters
and we get to do this all over again.

Jerry, KE7ER

?
On Sun, Jun 3, 2018 at 03:44 pm, ajparent1/KB1GMX wrote:
Its not a drop in.? The filter would likely be hard to find and costly or for a one off salvage from?
an old junker commercial radio.?

I think Kenwood radios used a 63mhz filter or maybe ICOM.? so lets do a thought
experiment on what needs to be done.

The filter would need to be matched and like data for it will require experimental testing.
The T30-2 toroids could be reused and rewould and the cap for the L-networks changed
as needed.? The entire string of 3904s [all 6 of them] in the 45mhz section would have
to be some thing like 2n2369, or better BFR106s.?

Then the firmware has to be revised as the first lo needs to be higher to start maybe
65mhz and go up from there.??

So yes it can be done.? I don't have such a part so thats ruled out.? So for a one off
maybe, doesn't help everyone though. and even if the filter was not too expensive?
thats a lot of SMT and through hole work plus a new firmware.? At the production
level it could add significant cost and interrupt the product flow as you have all the
material in place and likely paid for.

Right now the most feasible option is bandpass filters and switching.? Cost wise the
parts are cheap is SMT inductors are used.? The trick there is drop in and play no
manufacturing tuning.

Allison
65861 - 65880 of 116815