Re: Harmonics and Relay Replacement
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On Wed, Oct 10, 2018 at 4:43 PM Jim Sheldon < w0eb@...> wrote: Thanks Mike, Ordered 10 of them from Arrow - even cheaper than Digi-Key by a couple of bucks and certainly much cheaper on the shipping with Arrow's free overnight shipping.
My Digi-Key order will be here in about an hour and I'll mod the two V4 boards I have.? After the Arrow order arrives tomorrow, I'll mod the 2 V3 boards and run the Spectrum tests on them.
Jim Sheldon, W0EB
------ Original Message ------
Sent: 10/10/2018 9:07:12 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement
For those in the USA, you can order these from Arrow electronics (). They are a little cheaper, plus you get free overnight shipping. I ordered some and will try to replicate Mike's results. Mike M. KU4QO
On Mon, Oct 8, 2018 at 3:54 PM Mike Doty via Groups.Io <mikedoty= [email protected]> wrote: I thought I would pass this along, for whatever it is worth.? I have two Ver 3 and one Ver 4 uBiTX rigs.? I have replaced K3, KT1, KT2, and KT3 relays with Axicom relays which has knocked down the 3rd, 5th, and 7th harmonic levels from -35dB to below -50dB on all 3 rigs without any board modifications to the LPF circuits.? This may be anecdotal but with 3 rigs showing the same results it may be something to consider.? I purchased the relays from Mouser - part # 655-V23105A5403A201.? Cost was $2.89 per relay plus shipping.? I've attached photos (sorry for the blurriness) showing the before and after results on my Ver 4 rig.
--73--? Mike? --? W0MNE
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Info is nice always go by inductance values for tuned circuits as per sch but not mechanical turns wound. If you wind same, needed inductance has to be checked and tweaked. On Tue, Oct 9, 2018 at 10:06 PM jim via Groups.Io <ab7vf@...> wrote:
From the uBITX website "circuit details" section :
Coil Details
L5, L7 : 12 turns on T30-6
L1, L2, L3, L4, L11, L12, L13 : 9 turns on T30-6
L14, L15, L16: 10 turns on T30-6
L14, L15, L16: 14 turns on T30-6
L20, L21, L22: 19 turns on T30-6
All the RF transfomers are 8-10 trifilar turns on FT37-43
Jim
On Monday, October 8, 2018, 11:24:09 AM PDT, cburf1@... <cburf1@...> wrote:
Hi all,
I'm about to embark on my first homebrew transceiver and have chosen the uBITX. I am lucky to have been given access to a large collection of unwanted though-hole components as we have gradually moved to surface mount at my company. For this reason, I am looking to do a project similar to this:
My questions for now all regard the toroidal transformers. I can't find any info about these.
1. What toroids are used?
2. How many wraps of wire?
3. Are there any off-the-shelf alternatives anyone knows of should I choose to buy them?
Thanks for the help.
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Re: Harmonics and Relay Replacement
Raj, Obviously the reading could as accurate as your crystal used
across AADE meter.
Nice to know that you own an AADE meter.
REGARDS
SARMA
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On Thu, Oct 11, 2018 at 2:16 PM Raj vu2zap <rajendrakumargg@...> wrote:
I don't trust my AADE meter below 1uH. I use a meter called DE 5000, it read commercial
sub uH inductors very accurately. The AADE meter was way off.
The DE meter can be set for 1,10,100 KHz measurement frequency. At 100K the meter
reads 1nH
Raj
You will need the accesories TL-21 and 22 ..
At 11/10/2018, you wrote:
Kees,
In measuring a Virtual relay and an Axicom relay that I have here, both show approximately 20nH.
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Re: Harmonics and Relay Replacement
I don't trust my AADE meter below 1uH. I use a meter called DE 5000, it read commercial
sub uH inductors very accurately. The AADE meter was way off.
The DE meter can be set for 1,10,100 KHz measurement frequency. At 100K the meter
reads 1nH
Raj
You will need the accesories TL-21 and 22 ..
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At 11/10/2018, you wrote: Kees,
In measuring a Virtual relay and an Axicom relay that I have here, both show approximately 20nH.
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Re: Purchase of uBitx on hold until?
Joe,
With 45MHz filter you may lose up to half the power. With SMD I get like 95% of stock.
Raj
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At 11/10/2018, you wrote: Are you saying that the second 45mhz mod can be removed from the TX with this mod? How much power loss is lost with the 45mhz is in place?
Nice work by the way. I?€?d like to try this for sure.
Joe
PS wheres Allison been? She must be on vacation.
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Re: uBITX new build, quiet audio #ubitx; volume control wired backwards
Hi, you are not alone, I did the same mistake. And evidently ver. 4 is more robust than ver. 3. I had to replace the audio final in ver. 3 (the good but infamous TDA).
Il 11/ott/2018 05:59, "Robin Midgett" < K4IDC@...> ha scritto: This is what happened to me with my first ?BitX; yellow volume wire was connected to volume wiper (Vol-M) & orange wire was connected to Vol. high, which is backwards. Once I corrected that, the audio problems disappeared. I verified the mistake using an ohmmeter; orange (Vol-M) should connect to junction of C72 & C78. I don't have the original instruction sheet handy but I'm pretty sure it was followed properly. I have v4.3 ?BitX.
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When I replaced Q13 after blowing it I used a 2N2222A as I had several on hand. I found the stage gain was significantly less and I had to increase the drive? to get the same power with modulation as I has seen before, so I suspect something like that may be true with the 2N3904 you used. Also, the output of various electret elements seems to vary a little and I've read that some add a mic preamp stage to accommodate the mic they used. Glad you got it figured out, though.
=Vic=
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Re: how to reset the calibration; AND calibration doesn't take until VFO is moved
I'm new to the ?BitX, and I'm working the bugs out of my ver. 4.3, first uBitx.
By reading through the messages, I see that I'm not alone with reversed LSB/USB. I got that sorted out, so that now conversations on 75m sound decent on LSB but then I found quite by accident that switching from LSB to USB & vice-versa doesn't take effect on the uBitX until the VFO is moved one step (50Hz)! I was confused by my own sanity check while listening to a conversation on 75m LSB; I switched to USB & was still copying the QSO as if nothing had changed, then accidentally bumped the VFO slightly & the QSO disappeared into the dirt. I could still detect the voices but they were low level, distorted & unintelligible. So, to confirm the event, I switched back to LSB, being careful to not bump the VFO, and the conversation was still distorted. I then moved the VFO slightly & BAM..the QSO was clear & intelligible.?
So, it seems that my current firmware (stock) has this bug of not changing modes unless the VFO is changed, causing the ?P to be motivated & update the L.O to the alternate frequency for the opposite sideband.
Have any of the readers noticed this? Is this another quirk that others know about or have experienced, or am I just behind the times (quite possible..)?
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Re: QSX 10W HF Linear PA kit
Hi Justin
> Hans will your upcoming transceiver? > kit have the option to add a TCXO oscillator???
Not sure yet...
73 Hans G0UPL? ?
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Re: uBITX new build, quiet audio #ubitx; volume control wired backwards
This is what happened to me with my first ?BitX; yellow volume wire was connected to volume wiper (Vol-M) & orange wire was connected to Vol. high, which is backwards. Once I corrected that, the audio problems disappeared. I verified the mistake using an ohmmeter; orange (Vol-M) should connect to junction of C72 & C78. I don't have the original instruction sheet handy but I'm pretty sure it was followed properly. I have v4.3 ?BitX.
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Re: Harmonics and Relay Replacement
Kees,
What is the difference between the 1.5 & 3in boards? Larger physical size makes it more effective?
--
Mike
AI4NS
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All:
I'm positive Hans said what the microcontroller was that controls his new QSX rig. While I'm pretty sure its an STM32, but I can't find which flavor or the post that (I thought?) mentioned it. Does anyone recall?
Jack, W8TEE
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Re: Harmonics and Relay Replacement
One more........
Inquiring minds want to know............
What is the power (or "sensitivity" level) of the AXICOM 12V relay relative to the others since there are typically 3 or 4 different power level options and the coil DC resistance will vary from about 320 ohms (high current) to 960 ohms (low current), depending on the option selected.
73 Kees K5BCQ
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Re: Harmonics and Relay Replacement
Note that the addition of a 100uH choke in series with the coil improved the attenuation 10dB......but there is that self resonance peak. Don't know the effect (yet) of having a 100uH (or larger) choke on every coil lead.
73 Kees K5BCQ?
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Re: Harmonics and Relay Replacement
Those inductances all look right. Sure would like to know WHY the Axicom relays have better readings.?
It just dawned on me that when I'm measuring all these little LPFs, whether I built them up or used the parts off the uBITX......the attenuation is not going to be better than what the filter by itself shows when tested separately. I'm generally seeing -50dBm to -55dBm (Including a couple of LPFs from Hans' QRP Labs) and that's apparently as good as it's going to get. Guess I was spoiled by a larger 3" board LPF, same component values as the smaller 1.5" boards but it has an attenuation down to -70dBm and starts getting close to the noise level of the Rigol. I may be making some overall improvements but the effect is "masked" by the actual filter capability.
The task at hand is to make the SYSTEM LPF attenuation as close to the individual LPF attenuation as possible through the use of different relays, relay wiring, RF chokes, etc, etc. And, of course, if the individual LPF design on those small 1.5" boards QRP Labs uses, can be improved. As Ben, NO5K, said....those "constant K" filter designs are known for having really bad SWR outside the intended bandwidth resulting in lots of nasty reflections.....as a Smith Chart reflection vector will show. The fix may be to add some inductance between the LPFs and the PA output, but the effects are difficult to see if the LPF capabilities "mask" them . More to scratch your head about.
73 Kees K5BCQ
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Re: Purchase of uBitx on hold until?
Hope she's ok.? Sorta suddenly stopped posting.
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Re: Harmonics and Relay Replacement
Your values look to be in line with what I measured, Jim.? .02uH is 20 nH.? I only measured one of each brand.
--Mike--
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Re: QSX 10W HF Linear PA kit
Hans will your upcoming transceiver kit have the option to add a TCXO oscillator???
-Justin N2TOH?
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Re: Harmonics and Relay Replacement
Thanks Jim.? That is quite promising. _._
On Wed, Oct 10, 2018 at 2:06 PM Jim Sheldon < w0eb@...> wrote:
I've just finished the tests up through 20 meters and it's only 40 that I have any issues with.
Test parameters - since the power output gets lower the higher in frequency you go, on each band I set the SA so that the carrier was on 0 dB each time I changed bands. My rf pickup is from a 50 ohm dummy load through a voltage divider to the SA to keep input below +30 dBM.
80 Meters 3.500 MHz 7.000 (2nd harmonic) - 65.7 dBC 14.000 (3rd harmonic) -76.4 dBC
40 Meters 7.000 MHz 14.000 (2nd) -58.0 dBC 21.000 (3rd) - 47.2 dBC
30 meters 10.000 MHz 20.000 (2nd) -76.9 dBC 30.000 (3rd) -75.8 dBC
20 meters 14.000 MHz 28.000 (2nd) -65.2 dBC 42.000 (3rd) -64.8 dBC
I didn't test 17, 12 and 10 meters at this time but I suspect their harmonic suppression is in the same boat as the rest.
I did do a quick test on 20 meters with 1KHz tone into the mic jack (I'm a CW op and don't keep a microphone in the shack), power out about 7 watts, SA set so carrier was 0 (top) of screen and got basically the same results - 2nd harmonic @ 28 MHz was -65.0 dBC and 3rd @ 42 MHz was -63.9 dBC, very close to the same as I got for CW.? There were a few spurs that showed up on the 20 meter test, but they were all -80 dBC or better (I do have the 2nd 45 MHz filter in place). ?
It appears that the Axicom relays DO provide a significant harmonic reduction over the originals used. ( Except for 40 meters on MY uBITX board.? I suspect there is something else in play there that I need to track down).? I still need to swap relays on the 2nd board and check it but as I said earlier that will be most likely tomorrow.
Jim Sheldon, W0EB
------ Original Message ------
Sent: 10/10/2018 2:37:30 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement
Thanks,? Jim for doing those tests!!
Sorry to hear the 3rd wasn't reduced any further.? ? In my tests of the external daughterboard idea, the 3rd harmonic on that particular band?was reduced by 1.5 S units, and calibrations with inline attenuators suggested 1 S unit = 12 dB in that region.?
?Due to the granularity of the S-unit display on the ICOM 718 it might have really only been just over 1 S Unit...but still it appears the daughterboard (which deals more with the wiring) achieved a higher degree of harmonic reduction.
It is great there is such a huge group of people working on various solutions!!!
Gordon..
Ref:? ??
OK peeps,
I measured the harmonics with my spectrum analyzer.? I can only show the fundamental, 2nd and 3rd harmonic so it's ?not a complete test, but the results though positive, are not all that encouraging.
First, with the original relays, Carrier @ 7.000 MHz set to 0 on the vertical scale. ?2nd harmonic was -58 dB from the carrier and the third was only -45 dB from the carrier.? I didn't measure the 4th & 5th though they were farther down than the 3rd.
Changed out the relays and measured again without changing any settings.
7.000 MHz carrier @ 0 (top) of the vertical scale. ?2nd harmonic was -67.6 dB down and 3rd was -47 dB down.? That was a 2 dB improvement on the 3rd harmonic but not enough to call it a reliable harmonic fix with the Axicom relays.? It did help and it IS
in spec, but there are other things that most likely need to be addressed to make it better.? It IS a step in the right direction and did NOT require complete re-design of the filters.? At least for 40 meters.
I will run the tests on the other bands and see how they come out, but I'm not holding out for much if any improvement over the 40 meter spec.
Ashhar Farhan, the Axicom relays DID help some in my V4 board, but not sure the added expense is justified for production.? I think the filter redesign on the production boards would be a far better long term solution IMO.
I am going to change out the relays on my other V4 board and test it as well but that will be later this evening or tomorrow.? If I don't report on that one, it will mean I didn't find any significant difference between the two boards.
The Axicom part # for the relays I used is V23105A5403A201.
Jim Sheldon, W0EB
------ Original Message ------
Sent: 10/10/2018 12:58:56 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement
Guys,
If someone else too can confirm this fix. We will start ordering axion relays from now on. - f
On Wed, 10 Oct 2018, 23:15 Jim Sheldon, < w0eb@...> wrote:
Yup, and after opening up one of the original relays that I removed from a V4 board in prep for putting new ones on (they should be here within the hour) it was extremely obvious that those relays were not designed with RF in mind.? There is no shielding
of the relay coil at all and all the contacts are on movable arms that run parallel to each other and the full length of the relay as well as close to the relay coil itself.? The armature is mostly made of plastic so doesn't provide much (if any) shielding
between the coil and the movable contact arms.? The movable arms are each made up of 2 parallel, approximately 2mm wide strips of metal that are separated in the middle of the top of the relay by about 1 mm. ?(Pictures not possible as the relays were pretty
much destroyed in the dissection.) ?I believe the parallel arm construction was for current carrying capability (not needed in small signal RF relays) as the contacts are rated to 125V @ 60 watts (their designation) in the data sheet.? The width & placement
of these contact arms would allow a whole lot of coupling between both sets of contacts and I really believe it's one of the culprits though not necessarily the entire problem. ?
Changing the relays to an RF rated set with proper isolation certainly can't hurt and may just wind up being the simplest fix for the problem.
The Postman just delivered the new relays from Digi-Key so off to install them and run some tests to see if I can prove or disprove Mike Doty's data. ?
I do believe my results will corroborate his after chopping up one of the old relays to see what was in it.
Jim Sheldon
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Re: Harmonics and Relay Replacement
How did you measure the inductance of the armature? ?I tried with my AADE LC meter and I get .02 to .028 microhenry on all 5 new relays. ?Not sure I'm using the right method to measure that particular inductance.
Jim - W0EB
------ Original Message ------
Sent: 10/10/2018 5:58:17 PM
Subject: Re: [BITX20] Harmonics and Relay Replacement
Kees,
In measuring a Virtual relay and an Axicom relay that I have here, both show approximately 20nH.
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Raj vu2zap
Vic WA4THR
Jim Sheldon