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Ashok

first of all, you did not specify SSB bandwidth or CW bandwidth.? Asshar describes design of SSB filter at 12 MHz on his BITX and uBITX circuit descriptions.?

narrow CW filters are described on the web - they typically use 3 or 4 crystals each shunted to ground with a capacitor.? the capacitor value influences the exact bandwidth.? often one uses a frequency counter to match these crystals to 10 of 20 Hz - not as important for a SSB filter.? usually the principle is to employ crystals from the same manufacturing lot so they are similar.?

the nice VNA is much more useful to measure the resulting filter.?

there is a nice QEX article on crystal filter design available on the web.? let me know if you cannot find it.?

Curt wb8yyy

I have a friend who has a Ver3 Bitx40 board.? It's been awhile since I've used Git Hub and can't find the
location to download Ver128.1.? I would appreciate it if someone could give me the link to the files so I?
can forward it to him.? Thanks much es 73 de AG0H

I just got mine s meter working, well kinda sorta. The s meter moves and the cw decoder sometimes decodes. It took me a few days to figure out the wiring, i didn’t see this post till after been done.?

One part that confused me quite a bit was that all the diagrams i saw show the nextion on pins 5 and 6 on the raduino. Im pretty sure that on v6 with the 2.8 screen header the nextion hooks onto pins 5 (which you tap for the s meter) and pin 11 with the blue wire. That’s how i had it hooked up before adding the s meter.?

Also a4 and a5 on the raduino, i could not figure out if they come out to a pin on the board. The only thing i found was near q1 on the raduino, which seemed like dead ends with test points.?
I ended up soldering header pins on the back of the raduino board were the header pins for the arduino are soldered.?

I do like the way you mounted your s meter nano. Right now mine is hanging by wires, and i soldered the resistors and cap directly to it. I think this is a good excuse to try my hand at etching a board to mount the second nano and have the resistors and cap smd mounted.?

Is there a specific way to figure out the numbers on the bitx manager. I put on there 4 at the lowest and 254 at the highest, then with the tool made is visually linear. The meter is responding, but i don’t know how accurate.?
and the cw decoder all it sees is e’s and t’s for the most part, even tho i was able to see some words get decoded earlier today.?

I’ll be checking this thread, because is the only one i found so far with the s meter on a v6.?

Thank you
luis
ko4byi

Hi all,
Can anyone guide me how to use VNA to design crystal filter. I am completely new to this VNA. Many forums mention this abt VNA and crystal filter but i cannot find any proper guide how to design crystal filter using VNA. I will use NANO VNA

Regards
Ashok?

Kb9lrw on the drawing seems like a clue, glad to see global enthusiasm.

An audio interface is much more vital than CAT. Primary function for CAT is to get correct band on the log. (-:

Everyone work to stay well. 73 curt

Okay

Before our expert designers get into it, let's not have global warming here.

Okay when I saw wanting 2 bands, I thought ubitx not bitx. For the latter, the 10w qrplabs amplifier could be a good fit, do check to make sure you don't overdrive it, I imagine that is in the instructions.? 10 watts from 2 or 3 watts will be noticed, and later apply it to a qsx.

Curt

On Tue, Mar 31, 2020 at 07:29 PM, McRuss wrote:

Thanks for the suggestions.? As for RF leakage, I'm in a situation where my dummy load is in a different state so can't do that.? I also have an issue with grounding since I'm in a condo with limited access to 'ground.'? But my other HF rigs seem to be OK with the same feed line.?

If you have limited access to ground ,you might be successful with an 'Artificial Ground'
It is a (variable)L ,(variable) C series resonant circuit with a sensitive mA or MicroA meter coupled to a toroid with the toroid sensing the current through the circuit . Connect one end of the circuit with the transceiver ground connection and the other circuit end? to a longest possible wire on the ground (possibly under the carpet )
At the operating frequency adjust L and C for maximum current as shown on the meter.
It is advisable to make the sensitivity of the meter adjustable with a (front-operated)potmeter
MFJ sell such a device . I have made one myself with the variable L being a roller inductor.
The MFJ variable L is stepwise -switchable
Ensure that the ground wire free end is properly insulated because there could be a HIGH RF VOLTAGE.

Frank? , EI7KS

Chris,

Not sure what version of bitx but most of them were 3-10W? so whatever your getting
now you want about 4x to make it worth your time.

The other is you must respect input power for the amp purchased for 20W amps
that means less than 2W input power some less.

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

MFJ sells the mount for the two hamsticks with bracket to mount to? pole:

Then buy the two other band sticks.

FYI
73
Evan
AC9TU

Sounds like a good, workable plan.

Good luck,

Ken, N2VIP

Well as mentioned on another post, the ubitx already has a more qro linear builtin,? when we bias the PA only at a higher voltage. But I would use a nearby RBN to see the level of my harmonic.

Yes low solar flux, and increasing QRN here at northern latitudes can discourage the ssb op.but there are other pursuits on Earth.

Curt

Hi,

The original post says bitx and not ubitx.

73,

Bill KU8H

--
bark less - wag more

Mark is correct in that you can run the finals at a higher voltage.? I have read of some at 20 votls.? Per Allison KB1GMX, the IRF510 is rated for 100 volts.? The other parts of the circuit may not be (an example is the electrolytic capacitors used to filter the PA voltage).? There is also the issue of heat dissipation of the IRF510s and the power rating of the LPF.? When the uBiTx was designed, there were tradeoffs made to keep the price point down.

Before I would go and risk the finals and maybe more parts in my only rig, I would spend the time reading through all of the information that I could find on PA voltage.? I would suggest you do a search of the board for "PA voltage" as I did and you will find references to things that you will need to do, as well as advice that you need to increase the transmit power by a factor of 4 to be noticed at the other end.? Also look into??for possible information.? You could start with:
/g/BITX20/message/53765?or?/g/BITX20/message/71653

Another source for an outboard amp:


FWIW
73
Evan
AC9TU

Mark

i was thinking the same thing, wanted someone who is powering their finals from 20 to 24 volts.?

Chris

note there are 2 wires on the positive side of the supply going to main board.? if you trace with an ohmmeter you can confirm which is which - very very important as 20-some volts will smoke most of the ubitx board, except the collector to the PA devices - these are uniquely on the second wire.? do get advise from someone who is running on 24 volts, but it does seem straight forward.?

do try your stock ubitx on a hot band the signals seem loud, and your few watts will get someplace.? it you can set up for FT8 that will also bring some contacts.? i confess I do plenty of CW with my ubitx - and don't presume you can't learn that.? if you use a repeater, you can learn part of the alphabet confidently as you keep hearing that - no need to hijack this thread - it is supposed to be about QRO - motivation to also do CW covered elsewhere here.?

everyone take care and radiate some, and cultivate some soil if it is Spring in your hemisphere.?

Curt wb8yyy