Date   

Crystal CW filter with Version 4 uBITX boards? #ubitx

Jim Sheldon
 

Has anyone successfully added a narrow crystal filter to the uBITX version 4 boards using Ashhar's included header connections? 

So far I've not been able to get a signal through filters at 4.6,  6.2 or 8 MHz.  The filters use closely matched crystals, They are Chebychev filters and have been designed with "ELSIE" for a 200 ohme input/output impedance with 4:1 transformers to match them to Ashhar's specified 50 ohms. Software has also been modified to allow moving the BFO and IF frequencies to match the filter's frequencies.  Can't seem to get enough signal through them to be useful though the software DOES put the IF where it should be.  I can hear a signal generator on whatever frequency the uBITX is tuned to, but it takes better than 10 microvolts input at the antenna for what I'd consider to be a usable CW signal in the headphones.

I built the filter using a 4 crystal - 200 ohm 8 MHz circuit with crystals and other components purchased from INRAD (Vibroplex now owns them) but either I haven't figured out the proper 4:1 transformers or there's just too much loss through the filter.  I have tried it with 4 and 6 MHz filters I made from scratch with only slightly better results (6 microvolts at the antenna for a usable signal)

Sure would be nice if someone was able to get something working to the point it was usable and repeatable, even on perf-board. 

The idea of switching the IF frequency to switch filters appears to be sound - just need to find the magic crystal/capacitor/transformer combination and for that I need someone with better knowledge of crystal filters and better test equipment that I have.

Thanks

Jim Sheldon, W0EB


Re: NEXTION DISPLAY UPDATES For KD8CEC ver 1.094 up

Kees T
 

WOW ! You guys are amazing. I'm very impressed with the graphics.

73 Kees K5BCQ (a non programing type)


Re: Removing insulation from fine wires

Jack, W8TEE
 

How much trouble would I be in if I said you appear to be a professional stripper?

Jack, W8TEE

On Friday, July 6, 2018, 12:13:54 PM EDT, Gwen Patton <ardrhi@...> wrote:


For enameled wire such as magnet wire, I use extra fine sandpaper when there's enough length. If it's extra-tough lacquer, I use a lighter. Recently, I tested the electric arc lighter I picked up because it looked nifty (I don't smoke) and could be recharged via USB, and it removed the lacquer right the heck now. Heavier gauge magnet wire is a little harder to de-lacquer using this method, but it does work. Hold the wire with pliers, not your fingers, though.

Other wire, it depends on the thickness and type of insulation. PVC insulation on thin wires I used to strip with my teeth, but given that I'm a lot older now, I don't put my teeth through that lest I loosen them inadvertently. Careful stripping with a pair of diagonal cutters, flush cutters, or the wire-cutter on a pair of needle-nose pliers works most of the time, except when I squeeze it too tightly and clip the end off. Murphy's Law tends to cause this when you just went to a lot of trouble to prepare the wire and you don't have a lot of extra length, such as when soldering thin coax to a connector. If you have lots of extra length, it'll strip perfectly without effort. But when it matters, you'll probably nip off the end at least once.

My pocketknife works for most wire, and I'm used to doing it carefully, so I don't nick the wire, though removing the outer jacket on coax does usually result in a couple of shield braid strands getting nicked.

I have the cheap strippers with little gauge-marked holes that simply never work and shouldn't be purchased as they're a waste of money. Get a good spring-controlled stripper or one with an adjustable gauge on it instead.


Re: Removing insulation from fine wires

Robert Ogburn
 

On Fri, Jul 6, 2018 at 09:13 am, Gwen Patton wrote  ".....electric arc lighter"
thanks for the lead!


Just built my ubitx, can't receive anything #ubitx-help #ubitx

andrew.pater.brown@...
 

Hi all,

I am super excited to play with this thing, so when I got the kit I immediately built it. It does power up, and I hear what sounds like radio static. If I tune to certain frequencies I can hear tones that change based on frequency selected. However, even just with a random wire (albeit only about 3 feet long in my testing, but the shortwave receivers I had as a kid didn't have much longer) I can't pick up anything recognizable as a voice or CW contact, even stuff like WWV (on 5, 10, 15mhz) or the powerful shortwave stations like brother stair or whatever.

A few notes that I don't think would affect it based on my knowledge, but I'll share anyway in case I'm wrong-

1) I'm using external PC speakers, powered ones - it's just what I have on hand.
2) I'm using a 13.8vdc power supply that I picked up from another HAM a long time ago. It works fine to power 2m band VHF radios and such that are for a mobile application. It's possible it's noisy, but I've located away from it as far as I can.
3) I 3d printed a case for my ubitx and lined it internally with aluminum foil tape to keep the CIA signals out. Er, did I say that? I mean, rather, mitigate some of the RF noise. I have tested inside and outside of this case and there was no noticeable difference, so I don't believe the foil is related.
4) At first I was building and trying it in my basement and hoped I just couldn't get a signal down there. But this morning I tried it upstairs as well, and there was still no signal at all that was recognizable as a voice or CW transmission.
5) I followed the directions on the build page and have gone back through and verified I did everything.

Any ideas what might cause this?

For reference, I learned HF stuff on a Drake TR4 which I receive just fine on with the same random wire. It's not like a full on 1/2 wave dipole of course but I can pick up signals clearly.


Re: Removing insulation from fine wires

Robert Ogburn
 

365 nm...   Here is a picture of the coaxial tool (Harbor Freight)


Re: Current Draw

ajparent1/KB1GMX <kb1gmx@...>
 

The DC supply current gove up with power and load mis-match.  Typicial current draw
at 10W is about 2A give or take.  At 80M without mods it tend to run 12-15W and a bit
more current.

As you go up in frequency the power out drops so the current well as well.  High SWR will
increase current drawn at any power out.

I'd not use a supply less that 4A.  I'd also not use an antenna over 2:1 SWR.

Allison


Re: ?- How high SWR before smoke?

ajparent1/KB1GMX <kb1gmx@...>
 

Ralph,

Calculate the capacitance of the transistor tab to heatsink with a .002 think mica insulator.
Do that first.  For both.

Now ground the heatsink to the board ground.  Not an issue.

Don't forget the RD16HHF uses the same package so it has about 4nh of lead and
bond wire inductance.  That means the tab and the enad connection point at NOT
at the same RF potential.  Ground the tab and the heatsink is now carrying RF current.

The RF coupling is already there via the output transformer.  

Allison


Re: ?- How high SWR before smoke?

ajparent1/KB1GMX <kb1gmx@...>
 

Yes< RD16s are speced for 12V nominal nd16V max.  Its not wimpy but specifically
designed for 12V RF systems.   

IRF510 is speced for 100V, max 4A @100C and is a very robust device given half a chance.
So its seemingly hard to fry.

BOTH devices will disappear if the voltages to the gate (RF or DC) exceed a safe value
like 12V for the RD16 and 20V for the IRF510.  THis can happen if the amp is unstable
and oscillates, due to Miller feedback (gate to drain capacitance) if there is a large
RF voltage on the drain and the circuit is not RF stable the coupling can be sufficient
bring the gate over the breakdown rating.  All mosfets have this limit, I've fried
MRF137s that way and exotic GaN mosfets too.

The fact that the RD16 tab is ground is handy... BUT at RF where you ground things
can be precarious as you can create incidental current loops that incite instability.
Please remember there is no such thing as ground only the circuit common
return point for currents.  If you ground the board and the tabs of the RD16HHF
you created a set of current paths that Farhan has no design participation in and 
may or may not be stable, likely the latter.

I run IRF510s a pair push pull in an amp at 28V and they do about 55W at 40 or 20M
and have done so for more than a decade.  24-30V range is a sweet spot for these.
Its suffered shorted coax, open coax, no coax and wrong TX filter switched in
without failure.  I will point out the power supply used inside that amp has a current
foldback at 4A, hint 4A at 28V is 112W input to the amp and its trying to put out
60+ watts at 40M.

I've also paralleled 8 IRF510s as 4x4 push pull to make a 200W+ 6M amp.  Runs best
at 28-30V for SWR resistance and max power at 36V was near 275W.  They are
decently good IMD at 28V not exceptional but in the range of as good as commercially
made VHF radios..  Seems to tolerate most abuses well so far.  At 28V it wants a 16A
(500W switch mode power supply) supply minimum and the devices are peaking
about 4A each!

I've used RF16HHF at 20W max because the are 12V use where the IRF510 is not quite as good
for IMD.    I have not found them to be fragile but not quite as rugged as the 510.

Both parts will self destruct if the amplifier is not stable.  This means either part.
It happens faster than a fuse.

With all that said....

Just worked on someone else's uBITX that had a problem on 40M, it produces half the
power as 80M (15W) or 20m!(10W)  Reason was the output PI filter has coils that were
mis-wound (wrong inductance).  Easy fix once discovered....  Why relevant  here? 
The amp was putting 11W into the filter and getting 5W out.... That means the reflected
power the amp was seeing was 6W  That is an SWR well over 6:1 and the finals were
happy and never failed.

High "SWR" rarely kills finals its often instability with reactive loads.  Overheating, over
voltage and over current can.    Believe it or not those are the same things that can kill
the venerable 6146! 

Allison


Re: PTT #ubitx

Ralph Mowery
 

Sort of normal depending on how you built it.  The mic and small push button is for those that want to use them for the mic and PTT.   I am thinking there are 3 resistors.  One is a 4.7  K resistor that must be used.  It is installed across the red and green wires going to the key jack.  Without it, the bitx may key up at random times.  If you have two other resistors they are used if using a 'bug' as a keyer for cw.  I guess that you installed the diode across the power input to the bitx for reverse power wire protection.  Be sure to install about a 3 to 5 amp fuse in the power wire (not supplied).

de ku4pt


On Fri, Jul 6, 2018 at 12:05 PM, Bill Maier <ciric50@...> wrote:
Just completed the wiring on my uBITX. I have a cheap microphone I was going to use, but it has no PTT switch so I guess I need to go get one with a switch. I did notice some parts left over after I finished the build - the electret mic, a tiny pushbutton switch, and a couple of resistors. Did I forget to do something, or is that normal?

-Bill  KG5RMJ
_



Re: NEXTION DISPLAY UPDATES For KD8CEC ver 1.094 up

Michel Dupuy
 

hello, have you planned the version for Nextion 3.5.

Thank you

Michel F1GTX


Re: Removing insulation from fine wires

Gwen Patton <ardrhi@...>
 

For enameled wire such as magnet wire, I use extra fine sandpaper when there's enough length. If it's extra-tough lacquer, I use a lighter. Recently, I tested the electric arc lighter I picked up because it looked nifty (I don't smoke) and could be recharged via USB, and it removed the lacquer right the heck now. Heavier gauge magnet wire is a little harder to de-lacquer using this method, but it does work. Hold the wire with pliers, not your fingers, though.

Other wire, it depends on the thickness and type of insulation. PVC insulation on thin wires I used to strip with my teeth, but given that I'm a lot older now, I don't put my teeth through that lest I loosen them inadvertently. Careful stripping with a pair of diagonal cutters, flush cutters, or the wire-cutter on a pair of needle-nose pliers works most of the time, except when I squeeze it too tightly and clip the end off. Murphy's Law tends to cause this when you just went to a lot of trouble to prepare the wire and you don't have a lot of extra length, such as when soldering thin coax to a connector. If you have lots of extra length, it'll strip perfectly without effort. But when it matters, you'll probably nip off the end at least once.

My pocketknife works for most wire, and I'm used to doing it carefully, so I don't nick the wire, though removing the outer jacket on coax does usually result in a couple of shield braid strands getting nicked.

I have the cheap strippers with little gauge-marked holes that simply never work and shouldn't be purchased as they're a waste of money. Get a good spring-controlled stripper or one with an adjustable gauge on it instead.


Perfect pop and click fix for CW only operators

Tom Cooper
 

I tried all the mods using 2n7000 switches and such, and found that the improvement always fell short of headphone usable.  I only operate CW and this mod removes the source of the problem, but disables the mic amp in the process.

The leading edge pop you hear when going from R to T is caused by current inrush to C64 (Q6 mic amp power) when the TX voltage is turned on by K1.  Removing R66 eliminates the pop completely, but the mic amp no longer works.

The click you hear when going from T to R is caused by the inrush current to C52 (Q70 AF pre-amp power) when the RX voltage is switched back on by K1.  Cutting the trace bringing RX voltage to R52 and connecting R52 to +12V keeps the AF pre-amp constantly supplied and eliminates the click.  There is a little noise from the RX voltage returning to other parts of the receiver but it does not bother me enough to find a fix.

I am now operating with no additional VE1BWV type anti-pop and it is a pleasure not to need it.

73,

Tom  W1EAT


PTT #ubitx

Bill Maier <ciric50@...>
 

Just completed the wiring on my uBITX. I have a cheap microphone I was going to use, but it has no PTT switch so I guess I need to go get one with a switch. I did notice some parts left over after I finished the build - the electret mic, a tiny pushbutton switch, and a couple of resistors. Did I forget to do something, or is that normal?

-Bill  KG5RMJ


Re: Smart Analog/Digital I/O Expansion and LCD Display for the uBITX. #firmware #ubitx #nano #radiuno

Dexter N Muir
 

Thanks, Arv (and All!). Now to research where in ZL (preferably local - find me on APRS.fi) and cost ... My present raduino is my second - I blew the first with stray wiring :(
There used to be a Dick Smith outlet here, but that's long gone - and far from the 'builder' outlet it was. I think there's a Jaycar 10 miles away, but I'm not mobile. Head down, tail up, here goes ...
73
Dex, ZL2DEX


Re: NEXTION DISPLAY UPDATES For KD8CEC ver 1.094 up

Bo Barry <wn4ghv@...>
 

And where is the 5" version? 🤔😂


On Fri, Jul 6, 2018 at 11:39 AM Joe <joeman2116@...> wrote:
We are pleased to announce the release for the larger  screen size for the Nextion screens being used with KD8CEC firmware  v 1.094 and up

This release is for the 3.2 and 3.2E and for the 7 inch Nextion display.

The screens have been redeveloped with new buttons , enhanced graphics to reflect each of the 2 display sizes.
This work is on going but due to high requests we have decided to release these versions which are fully functional and utilize the full display area.


VE1BWV(Joe)  and KN4UD (Allen)



See attached files - both ,hmi and tft for each screen




NEXTION DISPLAY UPDATES For KD8CEC ver 1.094 up

Joe
 

We are pleased to announce the release for the larger  screen size for the Nextion screens being used with KD8CEC firmware  v 1.094 and up

This release is for the 3.2 and 3.2E and for the 7 inch Nextion display.

The screens have been redeveloped with new buttons , enhanced graphics to reflect each of the 2 display sizes.
This work is on going but due to high requests we have decided to release these versions which are fully functional and utilize the full display area.


VE1BWV(Joe)  and KN4UD (Allen)



See attached files - both ,hmi and tft for each screen




Re: ?- How high SWR before smoke?

Jerry Gaffke
 

Should be fine, gets done all the time.
The drains are operating into a very low impedance, driving the antenna through that step-up transformer.
A little added capacitance there is not terribly significant.
The fact that they are mounted on the same heatsink is not an issue,
generally the heatsink is bolted directly to the chassis and is at RF ground.

Other than no need for heat sink insulators, the other big advantage of the RD16HHF1's
is a somewhat lower gate capacitance, so easier to drive when operating above 20 meters.
But the RD16HHF1's are no panacea, we have bigger problems with the uBitx's gain
through all those 2n3904's than we do with the IRF510's.
And unless you have a cure for Allison's  45mhz-DialFreq  spur,
    https://groups.io/g/BITX20/message/52838
you should be operating at low power for 21mhz and higher anyways.
If at all.

Another big advantage for some is that RD16HHF1's are "Real RF" parts, don't want
their rig soiled by some fool switching FET designed for use in automotive turn signal blinkers. 
If that's an issue for you, by all means go for it.   
But the IRF510's work just fine.

If you are worried about damage from high SWR or high Vcc, the IRF510's are the better choice.
Their max Vds is 100v instead of the wimpy 50v Vds max spec of the RD16HHF1's.

Jerry
 


On Fri, Jul 6, 2018 at 07:42 am, Ralph Mowery wrote:
I understand full well about how to isolate the irf510s electrically.  However has anyone given any thought as to what may happen, if anything, to the RF coupling if the transistors are mounted on the same heat sink ? 
 


Re: Removing insulation from fine wires

Robert Ogburn
 

Way back---I used my teeth...   
The insulation types available today preclude the use of a single hobby price tool. You need to develop your own method for striping the insulation for each insulation type.  My "go to" tools include butane lighters, very very very sharp pen knife used in the fashion described by Mr Davis, x-acto style hobby knife with #11 blade and a home made hot wire stripper...  For coaxial cable I find the "spin around tool" almost essential. They do need maintenance and periodic "calibration".
I still have not developed a technique for removing "enamel" insulation.  Trying strong UV @ 365nM currently...


Re: ?- How high SWR before smoke?

Ralph Mowery
 


I understand full well about how to isolate the irf510s electrically.  However has anyone given any thought as to what may happen, if anything, to the RF coupling if the transistors are mounted on the same heat sink ? 

On Fri, Jul 6, 2018 at 10:24 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Google "TO-220 insulator kit".  You can steal them from old equipment such as a computer power supply.
With two of those and some heat transfer grease, you can mount the IRF510's to one grounded heatsink.
The RD16HHF1's don't need the insulator kit, since the tab is the source pin, and gets grounded anyway.
But the insulator kits work well with the IRF510's.

t/ BITX Web Site of Mike ZL1AXG
https://groups.io/g/BITX20/wiki/home Wiki