Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
My own take on the end of filter relays has stalled, as my uBITX case is a bit too small to accommodate the pcb and relays. But here's an idea of it's fitting.??? AS per a previous post, seam soldered the ground plane of uBITX to the new PCB. Short (under 1/2") copper wire to the new board for RF connects.?? vk3pe  
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Get well soon. My son just had his gall bladder removed last month. His main issue was a very sore post operative belly button. We were glad his was finally removed at it was only functioning about 3% and was making him septic just about every other month.
On Sat, Aug 25, 2018 at 11:36 PM Gordon Gibby < ggibby@...> wrote: Well, I'm several days BEHIND on what I had planned on this project, but I have some baseline results finally.? ?(Had pancreatitis last week and gallbladder removed Monday and laid up a bit, then struggled several days with an open-repeater ics-ctrl repeater controller raspberry pi project to completion).
First goal was to develop a homebrew measurement lab in place of a spectrum analyzer, to allow baseline measurements of harmonic output from a stock ubitx v3/4.? ?(Prior to modification to add in a daughterboard filter relay repair described previously.)
Using a 50 ohm/16.6K ohm voltage divider built on top of a Heathkit cantenna ( 2 100 ohm in parallel to make the 50 ohm, checked with very low SWR well beyond 30 MHz on antenna analyzer to be sure not wirewound resistors) and 6 100K resistors in parallel to make the top of the voltage divider), created approximatelly 50 dB attentuator.
Then double shielded BNC coax patch cord to selected bnc attenuator right at the input to an ICOM 718 receiver.??
Tonight was initial tests.? ?First problem:? V4.3 of software would not go into CW mode no matter what I tried on the key terminals.? ?Finally gave up and reverted to my own modified v2.0 of the ubitx code which does transmit.? ?Next problem was my radio shack "wattmeter" indicates rather low outputs.....but may not be accurate at all so I just went forward.
"Attentuator" is the ADDITIONAL attenuator beyond the estimated 50 db at the cantenna.
Mode? ? ? ?Freq? ? ? Meas.Watts? Attenuator? ?Fundamental? ?2nd Harmonic? ?3rd Harmonic? 4th Harmonic? ?5th Harmonic
CW? ? ? ? ?3.505? ? ? ? 2? ? ? ? ? ? ? ? ? 20 dB? ? ? ? ? S9+25? ? ? ? ? ? ? ?S8? ? ? ? ? ? ? ? ? ? ? ? S8? ? ? ? ? ? ? ?not meas? ? ? ? ? S8
CW? ? ? ? ?7.080? ? ? ? 1? ? ? ? ? ? ? ? ? 20 dB? ? ? ? ? S9+25? ? ? ? ? ? ? ?S6? ? ? ? ? ? ? ? ? ? ? ? S8.5? ? ? ? ? ?not? meas? ? ? ? ? not meas
All I have is the little LCD screen of the ICOM 718....but the readings were quite steady and the tuning in of the signal was not critical at all.?For the very first crack at? this EVER in my life, I was much more impressed with the measurement setup than I was with the problems I was inhaving the little uBitx to perform for me to allow testing.? ? I'll fiddle with this a bit more to be sure I'm happy with some baseline readings before I begin hacking traces and building the circuit board I have for the outboard relays.? ?I may have some other "power meters"? [these allare just simple rf voltmeters posing as wattmeters]? and see if I get any more believable answers.??
Thanks,
gordon gibby kx4z
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Photo of what I had to do to fix the coil wiring
On Aug 28, 2018, at 20:50, Gordon Gibby < ggibby@...> wrote:
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OK....very preliminary results.
The effect of putting the relays on the BOTTOM included reversing the POLARITY of the coil wiring......oops!!? I knew that, but was hoping the relays were not polarity sensitive....oops... THEY ARE!!? ?So I had to cut traces and rewire all the relay coils on
the daughterboard....ouch.? ?But once I did that, it works.??
Now my battery is dying, so I only got very preliminary reulsts on one band onlly (80 meters) at lower than desired power, and not even the entire series, but it looks ASTOUNDING
CONDITION? ? MODE? ? ?FREQ? ? ?WATTS? ? ?FUND.? ? ?2ndHar? ? 3rdHar? ? ?4th Harm? ? ?5thHar
BEFORE? ? ? ? ?CW? ? ? ? 3.505? ? ? ?5? ? ? ? ? ? ? ?S9+30? ?S7.5? ? ? ? ?S8.5? ? ? ? ?S0? ? ? ? ? ? ? ?S8
AFTER? ? ? ? ? ?CW? ? ? ? 3.505? ? ? ?3.3? ? ? ? ? ? S9+25? ?S4? ? ? ? ? ? ?S2? ? ? ? ? ? S0? ? ? ? ? ? ? S0
I? have found a stronger charger for that battery and hope to have more results, but it will take an hour or more to charge the battery sufficiently to proceed....
But so far, I"M QUITE PLEASED --- and remember, I did this with crappy open wiring, on purpose, just to see how sensitive a modification might be to actual shielding etc.
Gordon
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
OK....very preliminary results.
The effect of putting the relays on the BOTTOM included reversing the POLARITY of the coil wiring......oops!!? I knew that, but was hoping the relays were not polarity sensitive....oops... THEY ARE!!? ?So I had to cut traces and rewire all the relay coils on the daughterboard....ouch.? ?But once I did that, it works.??
Now my battery is dying, so I only got very preliminary reulsts on one band onlly (80 meters) at lower than desired power, and not even the entire series, but it looks ASTOUNDING
CONDITION? ? MODE? ? ?FREQ? ? ?WATTS? ? ?FUND.? ? ?2ndHar? ? 3rdHar? ? ?4th Harm? ? ?5thHar
BEFORE? ? ? ? ?CW? ? ? ? 3.505? ? ? ?5? ? ? ? ? ? ? ?S9+30? ?S7.5? ? ? ? ?S8.5? ? ? ? ?S0? ? ? ? ? ? ? ?S8
AFTER? ? ? ? ? ?CW? ? ? ? 3.505? ? ? ?3.3? ? ? ? ? ? S9+25? ?S4? ? ? ? ? ? ?S2? ? ? ? ? ? S0? ? ? ? ? ? ? S0
I? have found a stronger charger for that battery and hope to have more results, but it will take an hour or more to charge the battery sufficiently to proceed....
But so far, I"M QUITE PLEASED --- and remember, I did this with crappy open wiring, on purpose, just to see how sensitive a modification might be to actual shielding etc.
Gordon
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Re: UBITX V3 TX GAIN VARIATIONS
Rod,
Your spice model is seriously wrong.? Reason common emitter amplifier gain is a
function AC beta and the short form definition of that is FT/F where FT is the device
FT (300mhz for 2n3904) and F is the working frequency.? Since that amp has
feedback R81 and R83 the gain is limited to that.? Also the load is not 400 ohms
as the pot and the next stage is less than 100 ohms.
The latter stages have lower impedance as well due to higher power and parallel
devices.? The input of the devices impedance are a product or parallel resistors, feedback
and emitter current.? At 20MA? the short form for device input resistance is 26b/Ie (ma)
or at 3mhz about 2600/20=130 ohms and at 30mhz its 260/20= 13ohms for 3904.
That does not take into account emitter resistor and parallel base resistor and the
feedback.? They all tend to depress that value to lower.? To develop power you
need lower collector load as well.
The effective gain at 3mhz is about 39 (18db)m based on feedback it falls to 16db
save for the beta? is now 10 and the possible gain is about 10db.? Thats an 8DB slope.
That assumes the emitter resistor is 10 ohms and the cap is .01uf.? IF its 8.2ohms
and 470 pf then the gain is lower at 3mhz but no higher at 30.
Whats why you need a higher FT.? IF you limit stage gain to 10DB then its flat
within about .2db. but you 8db short of gain to make the needed output.
Same problem with pre-driver and driver.? Measured power at 28mhz is under 60mW!
at 3mhz with the same settings the driver is nearly 750mW.? Tested units (n>5) all show
this 10-12db drop in power due to lack of drive.
Further note on the 3904.? The HFE peaks at low current (10mA)and sags at higher currents.
The 2N2222A(to18 part)? work better even thought the FT is the same but its HFE peaks at over
150ma.? For developing power that is important.? ?When you compare the devices in a swept test
bed the 2n3904 has a reducing gain-bandwidth product with increasing collector current.?
The 2n2222A it actually has a better gain bandwidth product at 100ma and at 20ma.
These are the things not in the spice model.? That is a light first pass.
Allison
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Sorry for email to wrong address
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I am software and not good with hardware.? So with the FCC reg's issue I have decided to sell my
uBITX boards.? I have a version 1 and a version 3 boards.? I am asking $70 each.? This does not include
anything but the populated radio board.? Would like to keep sale in US if possible.? You can contact me
direct at w2ctx @ comcast. net.
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Doesn't look like meeting before the BARC meeting will work out!
Frank (WQ1O) has suggested he reserve the Red Cross room for a meeting.? We could
set up a "local" digipeater and do some testing.? Also need to discuss changes to NETC
and where we want to take pac in the future.
rOn
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Relay control wiring
Brown wire picks ?off ground. (which is done several other places also)
Brown-white picks off TX +12 V
First white wire pics off KT one control signal
Red wire pics off KT2 control
Bottom white wire picks up KT3 ?control
Let¡¯s hope it doesn¡¯t let any smoke out!
On Aug 28, 2018, at 18:06, Gordon Gibby < ggibby@...> wrote:
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Show quoted text
Well, here is the photo of my attempt at cutting traces with a Dremel 200 tool and a tiny little bit that looks like an end mill !! ?
I learned the hard way that you have to hold this thing with two hands, ?come straight vertical, and don¡¯t come anywhere close to the inductors.?
I managed to touch L 14 twice, first time knocked off one of its ?wires, another time and it went ZING! ?somewhere in my room and I haven¡¯t found it yet. ? ?So until I find it, that filter is only going to have two sections!
Once I learn to be that careful, it wasn¡¯t very difficult. ? I ?used low speed on the Dremel tool. ?If you work really slow or you can create a denuded solder point for a trace that you needed to cut, And then solder ?to.?
Because I hadn¡¯t planned this in advance, I don¡¯t have great options for mounting the board but I¡¯ll figure it out. ?
<image1.jpeg>
On Aug 28, 2018, at 17:09, Gibby,Gordon L < ggibby@...> wrote:
Here are photos of the assembled board. ? I did break down and use shielded microphone cable for the relay control wires. ? Soldering those SMT inductors was a bit of a thrill with a Walmart soldering iron. ? As some of you suggested, I put the relays
on the ground plane side. ? The extra circuitry unused is for a regulated voltage.
<image1.jpeg>
<image2.jpeg>
On Tue, Aug 28, 2018 at 3:51 AM Tom, wb6b < wb6b@...> wrote:
Warren thanks,
I googled around and discovered I'm not the only one trying to prototype things with tiny chips. So, thanks for pointing the Adafruit one out. I'll order the Adafruit one or see what Digi-Key has.
Tom, wb6b
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all those values Chris is quoting for the IN 4148 are completely at variance with data sheet values.
? which is good for 100mA forward? and 100V PRV.
NB unless the "opposite diode" fails, the non conducting diode can never see the peak reverse volts? in any case.
Summary. Two off Germ diodes in anti parallel are slightly better protection in that they will conduct at reasonable currents slightly earlier when forced by a low impedance sine wave.? ?However the price of this might be a slightly deafer receiver.?
The maximum allowable forward currents for the two are close enough not to be? a significant factor.?
If the radio is to be exposed to heat the Ge forward voltage (which is all that is letting anything get through to the transistor as opposed to being shunted) will fall faster than for the equiv Silicon diode.
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
... and for long unwanted sections, heat and lift one end and rip off the rest.
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
OK, here are photos of the completed RF wiring. ? Remember, this is intentionally done in the most simplistic manner possible. ? Short, but unshielded wires. ?The red wire, the input to the whole filtering thing, just cries out for either shielding or twisted
pair treatment, but I want to see what improvement you get from even very very simple wiring. ?
The daughterboard gets grounded at at least two points. ?See the black wires heading to two of the grounding posts of the main board.
Since I clobbered one of the inductors on one of the filters, I wired to just the last two sections of that filter.?
Next is to decipher the relay control wiring and figure out where to pick up my signals there. ??
This part went much quicker than I thought it would go. ??
On Aug 28, 2018, at 18:05, Gibby,Gordon L < ggibby@...> wrote:
toggle quoted message
Show quoted text
Well, here is the photo of my attempt at cutting traces with a Dremel 200 tool and a tiny little bit that looks like an end mill !!
I learned the hard way that you have to hold this thing with two hands, ?come straight vertical, and don¡¯t come anywhere close to the inductors.
I managed to touch L 14 twice, first time knocked off one of its ?wires, another time and it went ZING! ?somewhere in my room and I haven¡¯t found it yet. ???So until I find it, that filter is only going to have two sections!
Once I learn to be that careful, it wasn¡¯t very difficult. ??I ?used low speed on the Dremel tool. ?If you work really slow or you can create a denuded solder point for a trace that you needed to cut, And then solder ?to.
Because I hadn¡¯t planned this in advance, I don¡¯t have great options for mounting the board but I¡¯ll figure it out.
[image1.jpeg]
On Aug 28, 2018, at 17:09, Gibby,Gordon L <ggibby@...<mailto:ggibby@...>> wrote:
Here are photos of the assembled board. ??I did break down and use shielded microphone cable for the relay control wires. ??Soldering those SMT inductors was a bit of a thrill with a Walmart soldering iron. ??As some of you suggested, I put the relays
on the ground plane side. ??The extra circuitry unused is for a regulated voltage.
<image1.jpeg>
[image2.jpeg]
On Aug 28, 2018, at 11:53, Arv Evans <arvid.evans@...<mailto:arvid.evans@...>> wrote:
Breakout boards
<>
<>
<>
<>
_._
On Tue, Aug 28, 2018 at 3:51 AM Tom, wb6b <wb6b@...<mailto:wb6b@...>> wrote:
Warren thanks,
I googled around and discovered I'm not the only one trying to prototype things with tiny chips. So, thanks for pointing the Adafruit one out. I'll order the Adafruit one or see what Digi-Key has.
Tom, wb6b
<image1.jpeg>
<image2.jpeg>
<image1.jpeg>
<image2.jpeg>
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Dremel? Butchery! Scalpel / craft knife (even box-cutter!) can do a neater safer job. Slice across both ends of the gap you want to create, use your soldering iron/station to overheat the section of track and swipe it sideways. Then use the blade to? scrape bare the track ends? for solder points.
73 de ZL2DEX
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While it sounds like the diodes are lower voltages, should this protect the relays from a near by xmitter??
This is the mod thats mentioned to protect Q13, wondering if the diodes I have will be good enough to protect it:
"At pin 12 of K1 relay solder 2 4148 diodes in parallel but in opposite polarity. This will limit the receiver from getting high RF voltage."
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The NTE109 is a Germanium diode, equivalent to a 1N270.? It turns on
at a lower voltage, about .3V, than a 1N4148 Silicon diode, which
turns on at about .6V.
David N1HAC
On 8/28/18 6:21 PM, Chris [N7CCX]
wrote:
toggle quoted message
Show quoted text
I am going through my stash of diodes and found I had a couple of
NTE 109 diodes..?
The diode is
60 mA Continuous Average Forward Current, 100V Peak Reverse
Voltage..
The 1n4148 is 10ma 20v reverse; significantly different
values.
Is the NTE still enough of a limit that the bitx40 would be
safe from a nearby xmitter???
Thanks!
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I am going through my stash of diodes and found I had a couple of NTE 109 diodes..?
The diode is 60 mA Continuous Average Forward Current, 100V Peak Reverse Voltage..
The 1n4148 is 10ma 20v reverse; significantly different values.
Is the NTE still enough of a limit that the bitx40 would be safe from a nearby xmitter???
Thanks!
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Hope you find it. Better the one that is gone, than if one in the two filters for lower bands was lost.
Tom, wb6b
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Re: Right-sided relay harmonic attempted fix for v3/4 ubitx
Well, here is the photo of my attempt at cutting traces with a Dremel 200 tool and a tiny little bit that looks like an end mill !! ?
I learned the hard way that you have to hold this thing with two hands, ?come straight vertical, and don¡¯t come anywhere close to the inductors.?
I managed to touch L 14 twice, first time knocked off one of its ?wires, another time and it went ZING! ?somewhere in my room and I haven¡¯t found it yet. ? ?So until I find it, that filter is only going to have two sections!
Once I learn to be that careful, it wasn¡¯t very difficult. ? I ?used low speed on the Dremel tool. ?If you work really slow or you can create a denuded solder point for a trace that you needed to cut, And then solder ?to.?
Because I hadn¡¯t planned this in advance, I don¡¯t have great options for mounting the board but I¡¯ll figure it out. ?
On Aug 28, 2018, at 17:09, Gibby,Gordon L < ggibby@...> wrote:
toggle quoted message
Show quoted text
Here are photos of the assembled board. ? I did break down and use shielded microphone cable for the relay control wires. ? Soldering those SMT inductors was a bit of a thrill with a Walmart soldering iron. ? As some of you suggested, I put the relays
on the ground plane side. ? The extra circuitry unused is for a regulated voltage.
<image1.jpeg>
On Tue, Aug 28, 2018 at 3:51 AM Tom, wb6b < wb6b@...> wrote:
Warren thanks,
I googled around and discovered I'm not the only one trying to prototype things with tiny chips. So, thanks for pointing the Adafruit one out. I'll order the Adafruit one or see what Digi-Key has.
Tom, wb6b
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UBITX V3 TX GAIN VARIATIONS
Investigating transmit gain in UBITX V3 using LTSPICE, Aug 28, 2018
Caveats:
all modeling done at 13.8vdc
For simplification:
q90 collector circuit modeled as parallel feed with 400 ohm load
q911-q912 collector circuit modeled as parallel feed with 200 ohm load
q92,q93 and q96,q97 collector circuit modeled as parallel feed
??????????????????? with 50 ohm load,each side
observations:
in the bidir amps the 2n3904 gain rolls off 1.2 db from 5MHz
to 45 MHz...not real bad; I believe 2n3904s are quite usable
in the bidir amps at 45 MHz.
In the TX:
q90 rolls off less than .5 db from 5 to 30 MHz
same for Q911-Q912
same for Q92,Q93,Q96,q97
so, adding q90 rolloff, and q911-912 rolloff, and q92,q93,q96,q97
rolloff I get (.5+.5+.5)= 1.5 db rolloff from 5 to 30 MHz.
My most recent ubitx v3 has 10W out on 40M, but less than 2W out on 15M.
That is more than 7dB drop.
I take it from the above that replacing the TX driver transistors with
higher Ft devices may not substantially improve the 15M performance.
WARNING: q911,q912,q92,q93,q96,q97 all dissipate at least 296 mW. That
means 250 mW transistors are not acceptable.
So, in searching for a better Ft device for the TX chain:
the BFR106 has the dissipation, but the 3.5 to 5GHz Ft invites instability
the MMBT10? ?? lists dissipation at 225 mW, so it may not be a good candidate
the MMBT2369 lists dissipation at 225 mW, so it may not be a good candidate
the DTX2222A has the dissipation, but the Ft is not better than 2n3904, and
the footprint is not compatible with the board.
So at this point, I do not see a real winner for 2n3904 replacement.
I am sure open to suggestions on this front.
All of the above really leads me to question the power amp circuit..
and I do not have the wherewithall to model that successfully.
Any ideas there?
Rod KM6SN
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Yes, but we know this is not perfect.? Wrong word should been reasonable.
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David McGaw
