Re: ubitx spurs? Added LPF
I'd say C212 and L7 form one matching network, C214 and L5 form another matching network.
As Curt noted, the 0.1uF caps at C211 and C215 are extremely large at 45mhz, pretty much 0 ohms AC impedance.
They are there to prevent any DC across the quartz crystal, which could permanently degrade it.
Jerry, KE7ER
On Sat, Apr 13, 2019 at 06:44 PM, Joe Puma wrote:
Thanks Curt. I probably meant C212 which is 22pf. Gets a little rough remembering component numbers when youre trying to recount. :) ?
?
|
Re: ubitx spurs? Added LPF
Thanks Curt. I probably meant C212 which is 22pf. Gets a little rough remembering component numbers when youre trying to recount. :) ?
toggle quoted message
Show quoted text
On Apr 13, 2019, at 8:56 PM, Curt via Groups.Io < wb8yyy@...> wrote:
Joe
C215 is part of the matching circuitry used with the 45 MHz xtal filter -- 0.1 uF is a pretty large value at 45 MHz -- and it is large enough that it resonates with the coil way above this.? it seems to be a capacitive voltage divider to aid in impedance matching the filter.? possibly what you used is just fine -- I don't fret if I have to replace a SMT with a leaded part.? at these low frequencies the physical size of the cap isn't a big deal - when it fits the space.?
John
FB on your mods - those relays are said to often to fix the harmonics, and sometimes also help with mixer spurious.? the new filter you added is intended to fix SSB spurs on 15/12/10m.?
on 12m I think I see your spurious down at - 39 dBc.? that is ever so close to the goal (much better than my - 34 dBc) that if you experiment with slightly less audio drive you may be compliant enough.?
I think what you did was adding a new LPF placing it between the 'bi-directional amplifier' and the 'final mixer on transmit' (aka first receive mixer) - juslike v5.? I am especially curious with this result - and if you think it gave you some spur reduction - great news.? Raj is doubting the vertical orientation but your results seem to be good.? check your CW output now especially on 40 and 80 meters -- hopefully at least 5w on 40m and more on 80m.? (my rig and some v4's appear to be 'haunted' on CW whenever parts are added here to fix the SSB spurs).?
possibly your rig is doing well.? nice instrument you have there.? enjoy your work.
Curt
|
Re: ubitx spurs? Added LPF
Joe
C215 is part of the matching circuitry used with the 45 MHz xtal filter -- 0.1 uF is a pretty large value at 45 MHz -- and it is large enough that it resonates with the coil way above this.? it seems to be a capacitive voltage divider to aid in impedance matching the filter.? possibly what you used is just fine -- I don't fret if I have to replace a SMT with a leaded part.? at these low frequencies the physical size of the cap isn't a big deal - when it fits the space.?
John
FB on your mods - those relays are said to often to fix the harmonics, and sometimes also help with mixer spurious.? the new filter you added is intended to fix SSB spurs on 15/12/10m.?
on 12m I think I see your spurious down at - 39 dBc.? that is ever so close to the goal (much better than my - 34 dBc) that if you experiment with slightly less audio drive you may be compliant enough.?
I think what you did was adding a new LPF placing it between the 'bi-directional amplifier' and the 'final mixer on transmit' (aka first receive mixer) - juslike v5.? I am especially curious with this result - and if you think it gave you some spur reduction - great news.? Raj is doubting the vertical orientation but your results seem to be good.? check your CW output now especially on 40 and 80 meters -- hopefully at least 5w on 40m and more on 80m.? (my rig and some v4's appear to be 'haunted' on CW whenever parts are added here to fix the SSB spurs).?
possibly your rig is doing well.? nice instrument you have there.? enjoy your work.
Curt
|
Re: CW key sticking with Nextion LCD ¡ª FIXED
So it¡¯s looks like I got to the bottom of the problem where RF seemed to be getting into the delay of the CW and causing chattering in my auto tuner plus a hiss in the speakers. ?
It was due to the IF out pan-adaptor wire I installed and when the wire In rear was plugged into SDR it seemed to allow RF to get in. ?I also changed the resistor I was using as a buffer and replaced it wit a 22pf. It seems not to effect the circuit better then the resistor. ?
Anyway I added 3 ferrites to the coax piece from my tap to the BNC connector on then back of radio. It¡¯s doing a good job keeping the RF out, that¡¯s what it needed. I also went through an exercise of replacing all wires with shielded cables, which all helps to keep the RF gremlins at bay. ?
I ordered some small ferrite rings to wrap any misc single wires but my problem seems to be resolved. ?
Joe
toggle quoted message
Show quoted text
On Apr 12, 2019, at 8:35 AM, Jack Brabham - KZ5A < kz5a@...> wrote: There is a uBitx "keying" board by W0EB on QRP Guys, might be relevant to your issue.
73 Jack KZ5A
|
Re: ubitx spurs? Added LPF
The power mod is easier then figuring out spurs and harmonics. ?You certainly don¡¯t need that expensive scope for it :) I just did mine and I guess I¡¯m getting the 14w on 80 and 6w on 10 like Allison mentioned. She does best power wise on 20 meters for me, not Alison but my uBitx :)
I¡¯m watching your work here though as I want to do the filtering Farhan mentions and use my poor mans analyzer to see if I notice a difference.?
And....I don¡¯t mean to hijack the post by hey Raj what do you think about my L5, L7 work? :)?
 ?
Can someone tell me what C215 does? Mine went bad on me from attaching the IF out for SDR so for a while I was getting poor performance until I replaced it. I didn¡¯t have a 1206 and not the right value of 0805 so I used a 22uf pin hole ceramic cap. Just curious what that part dose right before it goes into the filter. ?Now with the new, part my SSB audio is peaking to full wattage nicely.?
Joe? KD2NFC?
toggle quoted message
Show quoted text
On Apr 13, 2019, at 6:50 PM, John Sutter < jds@...> wrote:
This is a V3 that has new relays and
the L5/L7 fix and working on the LPF
that I believe is before the mixer, but I'm not sure.
I've been taking measurements at each step.? So far not
significant drops.
I had some crazy readings which where later explained by one of
the techs saying,
"don't use that one..." but at least it was consistent in relative
readings.
That said, I do see power go down with frequency across all
changes regardless of mods.
I think I saw a mod for that, but that one's probably not for me.?
We'll see.
On 12m I saw 32, 16, and 12Mhz
<pjeijlfghkjpbbdb.jpg>
On 10m, I had 32, 16, and 12MHz and then 7.86 MHz
<cpmofleofcibhidm.jpg>
On 4/13/2019 3:22 PM, Curt via Groups.Io wrote:
John
very good - I am interested in your results on this, and which
ubitx version you have.?
on 12m you might notice 2 spurs on either side of the carrier
about 5 MHz apart,? the v5 comes with a LPF similar to you have
drawn already installed.? I tried one using SMT inductors on my v4
-- not much change -- not surprising since the spurs are close to
carrier.? I did change R26 on mine, but I still have stock 2n3904
transistors (if I were bored I might see what better old stock
transistors I might have for 45 MHz - but that might be an
adventure).?
on your 12 and 10m readings you are mostly focused on harmonics of
the RF output.? either your close-in spurs are good -- or you
didn't notice them??
you could be a little confused as this LPF is described as
filtering harmonics of 45 MHz.? one of those 2 spurs I mentioned
seems to be 90 MHz - the LO frequency.? the other spur I think is
the PA signal leaking back to the mixer, and mixing again. ?
with any changes you make in this part of the circuit - do see if
you get any reduction of CW output power -- mine does a bunch on
40 and 80 meters. ?
73 Curt
?
<cpmofleofcibhidm.jpg>
|
Re: ubitx spurs? Added LPF
This is a V3 that has new relays and
the L5/L7 fix and working on the LPF
that I believe is before the mixer, but I'm not sure.
I've been taking measurements at each step.? So far not
significant drops.
I had some crazy readings which where later explained by one of
the techs saying,
"don't use that one..." but at least it was consistent in relative
readings.
That said, I do see power go down with frequency across all
changes regardless of mods.
I think I saw a mod for that, but that one's probably not for me.?
We'll see.
On 12m I saw 32, 16, and 12Mhz
On 10m, I had 32, 16, and 12MHz and then 7.86 MHz
On 4/13/2019 3:22 PM, Curt via Groups.Io wrote:
toggle quoted message
Show quoted text
John
very good - I am interested in your results on this, and which
ubitx version you have.?
on 12m you might notice 2 spurs on either side of the carrier
about 5 MHz apart,? the v5 comes with a LPF similar to you have
drawn already installed.? I tried one using SMT inductors on my v4
-- not much change -- not surprising since the spurs are close to
carrier.? I did change R26 on mine, but I still have stock 2n3904
transistors (if I were bored I might see what better old stock
transistors I might have for 45 MHz - but that might be an
adventure).?
on your 12 and 10m readings you are mostly focused on harmonics of
the RF output.? either your close-in spurs are good -- or you
didn't notice them??
you could be a little confused as this LPF is described as
filtering harmonics of 45 MHz.? one of those 2 spurs I mentioned
seems to be 90 MHz - the LO frequency.? the other spur I think is
the PA signal leaking back to the mixer, and mixing again. ?
with any changes you make in this part of the circuit - do see if
you get any reduction of CW output power -- mine does a bunch on
40 and 80 meters. ?
73 Curt
?
|
Re: ubitx spurs? Added LPF
John
very good - I am interested in your results on this, and which ubitx version you have.?
on 12m you might notice 2 spurs on either side of the carrier about 5 MHz apart,? the v5 comes with a LPF similar to you have drawn already installed.? I tried one using SMT inductors on my v4 -- not much change -- not surprising since the spurs are close to carrier.? I did change R26 on mine, but I still have stock 2n3904 transistors (if I were bored I might see what better old stock transistors I might have for 45 MHz - but that might be an adventure).?
on your 12 and 10m readings you are mostly focused on harmonics of the RF output.? either your close-in spurs are good -- or you didn't notice them??
you could be a little confused as this LPF is described as filtering harmonics of 45 MHz.? one of those 2 spurs I mentioned seems to be 90 MHz - the LO frequency.? the other spur I think is the PA signal leaking back to the mixer, and mixing again. ?
with any changes you make in this part of the circuit - do see if you get any reduction of CW output power -- mine does a bunch on 40 and 80 meters. ?
73 Curt
?
|
Re: ubitx spurs? Added LPF
Good point.? Earlier in this thread it
was recommended that I add
a LPF to get rid of the spurs on 15, 12, and 10m.
It was my understanding that the following (from Ashar I believe)
is the one (though #1 is backwards).
I've picked up some 0.33 uH SMD inductors I'll try today.
If that's not the right one, I could use a pointer to it.
On 4/13/2019 12:45 PM, Curt via Groups.Io wrote:
toggle quoted message
Show quoted text
John
You aren't clear in this message which spurs you are trying to
solve, nor where you are putting this new filter?
If this is an added 45 MHz filter, adjacent to the mix to and from
RF, then its objective is to reducing non harmonic mixing spurs
typically found on 15, 12, and 10 meters. A common problem with v3
and v4, maybe less so on v5. Note this mixing only happens on ssb.
In the last dB or to audio drive is a big deal. If my rig measured
say 41 dB down at full output, note if I ran digital at less
output I would likely be okay. For voice one might debate the last
dB since our voices don't stay at peak amplitude.
Curt
|
Re: ubitx spurs? Added LPF
John
You aren't clear in this message which spurs you are trying to solve, nor where you are putting this new filter?
If this is an added 45 MHz filter, adjacent to the mix to and from RF, then its objective is to reducing non harmonic mixing spurs typically found on 15, 12, and 10 meters. A common problem with v3 and v4, maybe less so on v5. Note this mixing only happens on ssb. In the last dB or to audio drive is a big deal. If my rig measured say 41 dB down at full output, note if I ran digital at less output I would likely be okay. For voice one might debate the last dB since our voices don't stay at peak amplitude.
Curt
|
Re: ubitx spurs? Added LPF
I was about to dig into my parts bin searching for toroids and
I remembered I had those left over.
I'll probably have to order some 30 uH parts.? 27 and 33 are easy to get locally, 30 maybe not.
Sounds like the way to go, thanks.
John
toggle quoted message
Show quoted text
On 4/13/2019 6:28 AM, Raj vu2zap wrote: John,
Very neat job on L5 and L7.
Make the 45MHz IF new filter with SMD parts. What seems to be the culprit is any vertical wire leads in that area
causes trouble. Solder the SMDs directly on the board.
When I get back to town tomorrow I will try it.
Raj
|
Re: ubitx spurs? Added LPF
|
Re: ubitx spurs? Added LPF
Ok, I have mounted the LPF filter in a Manhattan style without any glue so I had more flexibility in positioning the toroids, which are very light. I am not sure I understood your spreadsheet. The filter was assumed to reduce some spurs above the 17m band. I'd tuned at 28mhz you should see a 17mhz spur quite attenuated than without this filter (28+17=45mhz). At 21mhz the spur at 28mhz should be attenuated (21+24=45mhz), so on and so forth for any frequency above the 17m band. You show spurs that are not related in this way.
Il 13/apr/2019 11:55, "John Sutter" < jds@...> ha scritto:
Well, that didn't go well.
Looking at it, the two toroids on the left are a little close.
I have a layer of grounded copper foil between
the PCB and the filter (insulated of course).
I might rebuild the filter lying flat.
It looks like I only have 40m and 30m for SSB now.
Input is 1KHz 50mv p-p.
Harmonics on CW follow the spur tables.? Only 80m is not usable
there.
Before
After
|
Re: ubitx spurs? Added LPF
Well, that didn't go well.
Looking at it, the two toroids on the left are a little close.
I have a layer of grounded copper foil between
the PCB and the filter (insulated of course).
I might rebuild the filter lying flat.
It looks like I only have 40m and 30m for SSB now.
Input is 1KHz 50mv p-p.
Harmonics on CW follow the spur tables.? Only 80m is not usable
there.
Before
After
|
Re: ubitx v5 down: IRF510 heatsink very hot immediately after turning on the radio
#ubitx-help
#ubitx
|
I use this ,from {Pacific Electret Microphone kit.Works great Dale/ka5who
On Fri, Apr 12, 2019 at 2:03 PM Curt M. < Kc3hjp@...> wrote: I bought a new old stock Cobra CB mic for $5 and gutted it.? I used the original switch that came with the mic and used the element that came with the uBitx kit and put a 4 pin mic connector on the cord.? I get good audio reports with the stock element.
Curt M.
|
Re: Standalone signal analyzer
Update: success with the signal analyzer install! I have moved into my new shack, but no antenna feed through? yet. So will test tomorrow. A lot accomplished today! Waiting on the new bc645 microphone, received the agc kit yesterday! One step at a time. Loving this journey! Breaking out the dummy load tomorrow for testing.
73,
Kelly K5AID?
|
Re: Standalone signal analyzer
I thought about that but I wanted to reduce the stress off that 7805 on the raduino, so I added the buck converter to run the display and the extra nano. I have loaded the signal analyzer software on the nano. I have updated the firmware on the raduino to add the signal analyzer with a nextion display and now have the ability to upgrade the raduino firmware, externally. Progress!?
73,?
Kelly K5AID?
|
Re: Standalone signal analyzer
Total current would not be even 1 amp, more like 100 ma.? Should not be a problem.? I do know that Dr Lee ran all of the devices off of the same Raduino supply, just added a heat sink.
73
Evan
AC9TU
|
Re: ubitx v5 down: IRF510 heatsink very hot immediately after turning on the radio
#ubitx-help
#ubitx
I just thought of another possible problem, Q74 might be shorted.? This would follow the symptom of the injected audio at the volume control not getting to the earphones.
I had feedback is and though that Q74 was the culprit, so did a ohms measurement at TP21 both on receive and transmit (without power to the finals).? Should vary from a couple of hundred ohms to the value of the volume pot (10k if I remember correctly).? I did not have any issues with measuring the resistance while powered.? All but the side tone are dc isolated by capacitors, and there is a 220k ohm resistor in that line.
73
Evan
AC9TU
|
Re: ubitx v5 down: IRF510 heatsink very hot immediately after turning on the radio
#ubitx-help
#ubitx
If you have access to a frequency counter or an oscilloscope I would next check the 3 clock signals coming from the Raduino to the uBitx board.?
If you measure approximately 45 MHz- dial setting in Mhz on clock#2, approximately 56 or 34 Mhz on clock#1 and the BFO frequency (11.0555 MHz on my rig) on clock#0, then the Raduino is good.? This can be checked with the Raduino removed from the rig and powered by a micro or mini USB cable depending on? the plug on the Nano in the Raduino.? You do need the display connected to the Raduino so you know what the frequency is.? You should connect the digital control connector as well.? Then measure the clock signals on the pins that would plug into the uBitx main board.
If the Raduino checks outs, then you will need to start doing static voltage tests on the active devices in the rig.
4 main differences between the v3 and the v5 uBitx
1 - First IF after the first mixer transistors were changed, so the static readings for that stage may be different
2 - The SSB crystal frequency was changed from 12 MHz to 11.059 MHz? This means the clock 2 and clock 0 frequences will be different
3 - The audio section was based on a different audio IC than the LM386
4 - The output LPF scheme was changed.
The last change would not affect the receiver.
I believe that there were other changes to improve key click and receiver audio muting.
Above are just suggestions.? I have both v4 and v5 boards, though not v3.
73
Evan
AC9TU
|
Raj vu2zap