Date   
Re: JackAl Voltage Chart

K5ESS
 

Zero Defects.   Ah yes.  Harkens back to the 60’s when McDonnell Douglas had a “Zero Defects” program.  They had big all hands meetings where execs exhorted all to have zero defects in their work and passed out Zero Defects coins to everyone.  It was a short lived program when it was realized that this was not the way to achieve high quality.  Ultimately they discovered Juran and Deming and launched into another quality improvement program.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of bill wright via Groups.Io
Sent: Tuesday, January 15, 2019 12:17 PM
To: BITX20@groups.io
Subject: Re: [BITX20] JackAl Voltage Chart

 

what ever happened to zero defects?.. Known bugs released will

continue to screw things up because someone will NOT get the word.

Bill kd5yyk

 


From: Jack Purdum via Groups.Io <jjpurdum@...>
To: BITX20@groups.io
Sent: Tuesday, January 15, 2019 7:46 AM
Subject: Re: [BITX20] JackAl Voltage Chart

 

Mornin' Christopher:

 

I hate releasing software with a known bug in it, even when it is one that doesn't really impact the functionality of the product. The bug is in the EEPROM that saves the setup information. An easy fix is to simply hard-code the values, but that requires programming which scares a lot of people. I know it's going to be a flat-forehead mistake on my part, so I'm fairly sure I'll get it fixed soon or have a viable work-around within a day or two.

 

 

Jack, W8TEE

 

 

On Tuesday, January 15, 2019, 1:06:17 AM EST, Christopher Miller <djmalak2k6@...> wrote:

 

 

Why not remove them, release the source and then release a new version /after/ you fix the bugs?

 

If I recall correctly this person also attacked people from posting off topic on their thread promoting their product. Its a little disappointing in my humble opinion.

 

KF4FTR

 

Re: JackAl Voltage Chart

Jack, W8TEE
 

Where do I say that I'm going to release it before I fix the bugs?

Jcak, W8TEE

On Tuesday, January 15, 2019, 1:35:20 PM EST, bill wright via Groups.Io <chief6226@...> wrote:


Don't know why a commons sense comment turns snarky.  If you are putting out crap
even if it is an experimenter source code, save the bugs until they are fixed.
As stated before, someone will NOT get the word.
Bill kd5yyk



From: Jack Purdum via Groups.Io <jjpurdum@...>
To: BITX20@groups.io
Sent: Tuesday, January 15, 2019 12:27 PM
Subject: Re: [BITX20] JackAl Voltage Chart

Jerry:

Exactly. Also, JackAl is an Open Source, experimenters platform, not just a product. It's meant to be dinked around with and we hope that's what buyers intend to do. There are still about a dozen free pins, 780K of flash, and 225K of SRAM left unused in JackAl, so there are plenty of idle resources. Hopefully, people with share their discoveries.

Jack, W8TEE

On Tuesday, January 15, 2019, 1:21:05 PM EST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:


If you want something that claims to have zero defects, I suggest paying more than $50 for it.
Check out the offerings from Lockheed Martin or Loral.

Jerry


On Tue, Jan 15, 2019 at 10:16 AM, bill wright wrote:
what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk
 


Re: JackAl Voltage Chart

Jerry Gaffke
 

Another possible strategy:  Sit on your hands till the Alpha 0.002 release of JackAl rolls out.
Jerry


On Tue, Jan 15, 2019 at 10:27 AM, Jack Purdum wrote:
Exactly.

Re: JackAl Voltage Chart

bill wright
 

Don't know why a commons sense comment turns snarky.  If you are putting out crap
even if it is an experimenter source code, save the bugs until they are fixed.
As stated before, someone will NOT get the word.
Bill kd5yyk



From: Jack Purdum via Groups.Io <jjpurdum@...>
To: BITX20@groups.io
Sent: Tuesday, January 15, 2019 12:27 PM
Subject: Re: [BITX20] JackAl Voltage Chart

Jerry:

Exactly. Also, JackAl is an Open Source, experimenters platform, not just a product. It's meant to be dinked around with and we hope that's what buyers intend to do. There are still about a dozen free pins, 780K of flash, and 225K of SRAM left unused in JackAl, so there are plenty of idle resources. Hopefully, people with share their discoveries.

Jack, W8TEE

On Tuesday, January 15, 2019, 1:21:05 PM EST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:


If you want something that claims to have zero defects, I suggest paying more than $50 for it.
Check out the offerings from Lockheed Martin or Loral.

Jerry


On Tue, Jan 15, 2019 at 10:16 AM, bill wright wrote:
what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk
 


Re: JackAl Voltage Chart

Jack, W8TEE
 

Jerry:

Exactly. Also, JackAl is an Open Source, experimenters platform, not just a product. It's meant to be dinked around with and we hope that's what buyers intend to do. There are still about a dozen free pins, 780K of flash, and 225K of SRAM left unused in JackAl, so there are plenty of idle resources. Hopefully, people with share their discoveries.

Jack, W8TEE

On Tuesday, January 15, 2019, 1:21:05 PM EST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:


If you want something that claims to have zero defects, I suggest paying more than $50 for it.
Check out the offerings from Lockheed Martin or Loral.

Jerry


On Tue, Jan 15, 2019 at 10:16 AM, bill wright wrote:
what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk
 

Re: JackAl Voltage Chart

Jack, W8TEE
 

That's not what he's saying. What he's suggesting is remove the features that aren't working correctly and release it that way, fix the bugs, and then put the fixed code back in. Well, as it turns out, Al found what the issue was and I'm working on the fixes. Hopefully they won't take too long and this one fix will fix both bugs.

Jack, W8TEE

On Tuesday, January 15, 2019, 1:16:57 PM EST, bill wright via Groups.Io <chief6226@...> wrote:


what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk



From: Jack Purdum via Groups.Io <jjpurdum@...>
To: BITX20@groups.io
Sent: Tuesday, January 15, 2019 7:46 AM
Subject: Re: [BITX20] JackAl Voltage Chart

Mornin' Christopher:

I hate releasing software with a known bug in it, even when it is one that doesn't really impact the functionality of the product. The bug is in the EEPROM that saves the setup information. An easy fix is to simply hard-code the values, but that requires programming which scares a lot of people. I know it's going to be a flat-forehead mistake on my part, so I'm fairly sure I'll get it fixed soon or have a viable work-around within a day or two.


Jack, W8TEE


On Tuesday, January 15, 2019, 1:06:17 AM EST, Christopher Miller <djmalak2k6@...> wrote:


Why not remove them, release the source and then release a new version /after/ you fix the bugs?

If I recall correctly this person also attacked people from posting off topic on their thread promoting their product. Its a little disappointing in my humble opinion.

KF4FTR


Re: JackAl Voltage Chart

Jerry Gaffke
 

If you want something that claims to have zero defects, I suggest paying more than $50 for it.
Check out the offerings from Lockheed Martin or Loral.

Jerry


On Tue, Jan 15, 2019 at 10:16 AM, bill wright wrote:
what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk
 

Re: JackAl Voltage Chart

bill wright
 

what ever happened to zero defects?.. Known bugs released will
continue to screw things up because someone will NOT get the word.
Bill kd5yyk



From: Jack Purdum via Groups.Io <jjpurdum@...>
To: BITX20@groups.io
Sent: Tuesday, January 15, 2019 7:46 AM
Subject: Re: [BITX20] JackAl Voltage Chart

Mornin' Christopher:

I hate releasing software with a known bug in it, even when it is one that doesn't really impact the functionality of the product. The bug is in the EEPROM that saves the setup information. An easy fix is to simply hard-code the values, but that requires programming which scares a lot of people. I know it's going to be a flat-forehead mistake on my part, so I'm fairly sure I'll get it fixed soon or have a viable work-around within a day or two.


Jack, W8TEE


On Tuesday, January 15, 2019, 1:06:17 AM EST, Christopher Miller <djmalak2k6@...> wrote:


Why not remove them, release the source and then release a new version /after/ you fix the bugs?

If I recall correctly this person also attacked people from posting off topic on their thread promoting their product. Its a little disappointing in my humble opinion.

KF4FTR


Re: low output only on 40m

jim
 

Couple 'o questions ...SSB or CW  and How is power being measured?  broadband watt meter ?

If so ..All emissions from the xmitter are being summed together (dc to daylight) ie fundamental + harmonics + spurs + ?

Jim

On Tuesday, January 15, 2019, 9:30:55 AM PST, Bill Cromwell <wrcromwell@...> wrote:


Hi Evan,

Here is a contrary report for you. The forty meter output on my uBitx is
close to the same as 80 amd 30 meters and close to 10 watts. I have the
red and brown power supply wires connected together and run all of my
radios on 12 volt batteries (~13 volts at no-load, full charge). Due to
tolerance stacks among all the various parts used each of these radios
will be at least a little different from all others. If any parts are
out of tolerance that is going to be more so.

Mine is a V3 with the non "WX" audio IC socketed. I am running the CEC
software but that has nothing to do with RF power out. Board version might.

73,

Bill  KU8H

On 1/15/19 12:10 PM, Evan Hand wrote:
> This 40m output is very low compared to others, however ALL reports that
> I have seen always seem to have the 40m output much lower than 20m. 
> Does anyone know the reason for the drop on 40m compared to 20m?  Is it
> related to spurs being measured as part of the power out?
>
> Trying to learn and understand.
>
> Evan
> AC9TU
>

--
bark less - wag more



Re: low output only on 40m

Bill Cromwell
 

Hi Evan,

Here is a contrary report for you. The forty meter output on my uBitx is close to the same as 80 amd 30 meters and close to 10 watts. I have the red and brown power supply wires connected together and run all of my radios on 12 volt batteries (~13 volts at no-load, full charge). Due to tolerance stacks among all the various parts used each of these radios will be at least a little different from all others. If any parts are out of tolerance that is going to be more so.

Mine is a V3 with the non "WX" audio IC socketed. I am running the CEC software but that has nothing to do with RF power out. Board version might.

73,

Bill KU8H

On 1/15/19 12:10 PM, Evan Hand wrote:
This 40m output is very low compared to others, however ALL reports that I have seen always seem to have the 40m output much lower than 20m. Does anyone know the reason for the drop on 40m compared to 20m?  Is it related to spurs being measured as part of the power out?
Trying to learn and understand.
Evan
AC9TU
--
bark less - wag more

Re: low output only on 40m

Curt
 

Evan

learn - yeah me too! 

if you convert the spurs to absolute power, relative to the carrier power - you can add them all up and see they are quite small.  power in dBm is 10 log (power in mw).  and convert something like a spur that is 20 dB down to a ratio of 0.01  (factor of 100).  so a 1 watt signal with 2 spurs 20 dB down, the power in the spurs is something like 0.02 watts ! 

but keep asking yourself and others questions - and not latching onto your first thought on what may be causing an issue [don't research the web to see how I have resembled this in the past on several projects!]

Allison

thanks for what to look for.  I never did build that RF probe or PHSNA yet (I will get the built someday and may not need them then ....) -- but I can do a simple sweep with my power meter and dummy load to see what is going on (I would be doing it except for being at work).  it seems that issue is after (on transmit) the two sets of 45 MHz filters it now has.  [yeah I cracked 2 SMT caps making this mod - but they were tombstone installed - so I realize they are delicate - I may have used leaded ones if my friend who kitted the filter told me the cap value ... our spur fix is this xtal filter (with 2 matching transformers) + Gordon's board of relays - we will have data on 23 units some day]

other than the response of the LPF, the only other thing I see that offers potentially narrow bandwidth are those chokes feeding the PA transistors - and that seems highly unlikely unless a hole bunch of turns were added to it. 

out of the box my ubitx was weaker on 40m - and I just brought it down further.  its nice on every other band.  [yes I blamed it on the xtal filter before I checked all the other bands.  ditto for snow and ice on my elevated vertical coil -- always check with a 50 ohm dummy load, or a simpler antenna not impact by ice's dielectric loading!] 

73 Curt

Re: Tracing receive signal for low signal

jim
 

Nothing specific ..Just be sure the voltage does not change when going from receive to transmit ..decreasing voltage due to current draw will increase spur/harmonic/cruft generation ..

Spur/harmonic measurement ...Back in the old days, hams used a "Grid Dip Meter" with the switch in the "diode" position as an "absorption wavemeter"

Jim

On Tuesday, January 15, 2019, 4:57:20 AM PST, Dave Space <davesspacebar@...> wrote:


Only running one supply and it's basically just an old wall wart adapter that can run at 12v.  Supplies help a lot?  Have any suggestions on supplies?

Re: low output only on 40m

Bill Cromwell
 

Hi,

Did you run this sweep through the filters with a spectrum analyzer or a wobbulator> Or did you just use the transmitter itself? Just because the filter labeled 40 and 30 meters works on 30 meters does NOT mean the attenuation curve is right for 40 meters. I think Allison mentions counting the turns in her latest post. She has posted about this exact thing before.

73,

Bill KU8H

On 1/15/19 11:41 AM, Curt via Groups.Io wrote:
Ted
thanks for communication - I know slightly more about symptom now --
first, it likely can't be what I thought - LPF - as this LPF also is used on 30 meters!  my 30m power is okay.
I just ran a sweep across all the bands into a dummy load -- every band except 40m is producing a lively output (my power meter is reading 10 watts on 160m * down to 4 watts on 10m -- its got a QRP scale, but it was calibrated a couple decades ago).  So I am convinced I have a substantial dip (reading less than 2 watts now on 40m).
since I am using a dummy load - I will get some data on the width of this notch.  it is almost like a choke isn't working around 7 MHz.
brief history: my ubitx has always been weaker on 40m.  I will confess it has one modification - an extra 45 MHz xtal filter placed on the other side of its IF amplifier.  this network made the 40m outage worse.  I saw a tip from Farhan to reduce R26 from 470 to 220 ohms to compensate for this filter loss - I made this mod.  but I can't blame it directly -- I got nice output on all other bands.
we have 22 other ubitx from the same or recent lot in our club -- maybe mine is acting different that the population -- we are still gathering data from builders.
the funny thing - these kind of problems always increase education, getting 'me' to examine places I would not be compelled to examine. let's see if I can learn anything, and get this thing fixed.
* yes I realize I have no low pass filtering of the second harmonic when operating at 1.8 MHz ... but my 160m vertical presents a dreadful match at 80m.  a nearby RBN receiver conveys I got at least 40 dB rejection by its non-report on 80m!  know your antenna before doing this - but several of us in NA operating a stock ubitx on top band.
73 Curt
--
bark less - wag more

Re: low output only on 40m

Evan Hand
 

This 40m output is very low compared to others, however ALL reports that I have seen always seem to have the 40m output much lower than 20m.  Does anyone know the reason for the drop on 40m compared to 20m?  Is it related to spurs being measured as part of the power out?

Trying to learn and understand.

Evan
AC9TU

Re: low output only on 40m

ajparent1/kb1gmx
 

Its not the first time I've seen the wrong toroids installed and 40 was messed up.

Make sure the toroids have something like 15 turns of wire on them.
Last one I'd seen had the same number of turns as the 10m toroids (about 9 turns).

Also of a cap in the circuit gets cracked it will have a similar effect.

Allison

Re: low output only on 40m

Curt
 

Ted

thanks for communication - I know slightly more about symptom now --

first, it likely can't be what I thought - LPF - as this LPF also is used on 30 meters!  my 30m power is okay. 

I just ran a sweep across all the bands into a dummy load -- every band except 40m is producing a lively output (my power meter is reading 10 watts on 160m * down to 4 watts on 10m -- its got a QRP scale, but it was calibrated a couple decades ago).  So I am convinced I have a substantial dip (reading less than 2 watts now on 40m). 

since I am using a dummy load - I will get some data on the width of this notch.  it is almost like a choke isn't working around 7 MHz. 

brief history: my ubitx has always been weaker on 40m.  I will confess it has one modification - an extra 45 MHz xtal filter placed on the other side of its IF amplifier.  this network made the 40m outage worse.  I saw a tip from Farhan to reduce R26 from 470 to 220 ohms to compensate for this filter loss - I made this mod.  but I can't blame it directly -- I got nice output on all other bands. 

we have 22 other ubitx from the same or recent lot in our club -- maybe mine is acting different that the population -- we are still gathering data from builders. 

the funny thing - these kind of problems always increase education, getting 'me' to examine places I would not be compelled to examine.  let's see if I can learn anything, and get this thing fixed. 

* yes I realize I have no low pass filtering of the second harmonic when operating at 1.8 MHz ... but my 160m vertical presents a dreadful match at 80m.  a nearby RBN receiver conveys I got at least 40 dB rejection by its non-report on 80m!  know your antenna before doing this - but several of us in NA operating a stock ubitx on top band. 

73 Curt

Re: Tracing receive signal for low signal

Jerry Gaffke
 

That's a pretty good summary, here's some minor corrections and
a major dump of nitty-gritty detail:

>  If you can fix the harmonics, then operation on bands 20m and lower in frequency 
> should not have the IMD issue.  You can reduce that with both Ashhar's and Raj's fixes combined.

Transmitter harmonics occur at integer multiples of the transmit frequency.
So if transmitting at 7mhz, you might have harmonics at 14 and 21mhz.
I would be happy enough on the harmonics  if folks just replaced KT1,KT2,KT3
with proper RF relays such as the Axicom, flat on the board.

Spurs are similar to harmonics, except they occur at unexpected frequencies that are not
multiples of the transmit frequency, can be due to harmonics in an earlier stage of the rig.
For example, the 90mhz harmonic of the 45mhz desired signal in the 45mhz IF stage
will also mix with the high side clk2 VFO, producing a spur at 2*45mhz - (DialFreq+45mhz)
Or your transmitter output (perhaps 7mhz) sneaks back into the 45mhz IF, and that mises with the VFO.
Raj and Farhan have both suggested fixes that are apparently good enough on the spurs
(replace L5,L7 with special shielded inductors, and/or add a low pass filter going into
the mixer at D1,D2 to knock out the harmonic from the 45mhz IF amp at 90mhz, respectvely).
One or the other (or both) should bring spurs mostly into spec.  (Might also want Farhan's 12mhz trap 
to deal with 12mhz crosstalk from clk0 into clk2, creating a 12mhz spur).
The worst spurs are at 15m, 12m and 10m, though there can be spurs beyond the -43dB spec on
the lower bands too.

IMD (intermodulation distortion) is what happens when a band of frequencies goes through a non-linear amp.
Those various components of your signal interact with each other, creating new close in frequencies.
For example, you are transmitting a two tone USB test on 7.2mhz, the tones at 7.2010 and 7.2015 mhz,
The second harmonic of 7.2015 at 14.4030 mixes with 7.2010 producing a new tone at 7.2020.
On the uBitx, IMD is mostly due to having the mike audio higher than it should be, the diode ring mixers
and the two IF amps get more signal than they can cleanly deal with and thus become non-linear.
Also some IMD due to the final amp.  Fixing IMD would take a major redesign of the uBitx, redistributing
gain away from those IF amps and adding more gain to the final power amp, nobody has given a
step-by-step recipe to do this yet in the forum.  Fortunately, IMD is considered a lesser sin than 
spurs and harmonics, the extra cruft is so very close in with the main signal such that everything still
pretty much fits into the bandwidth of a legal AM signal.

An RTL-SDR using one of the DVB-T dongles uses an 8 bit ADC to digitize the entire world of incoming signals.
There's generally enough noise to see only 7 valid bits of data out of such an 8 bit ADC.
An increase in signal power by 4x is equivalent to +6dB, and since power into a fixed 50 ohm load 
is proportional to the square of the voltage, that same +6dB is a doubling in the signal voltage. 
Each of those 7 binary data bits represents a doubling of voltage, so teh RTL-SDR has a range of 7bits*6dB/bit = 42 dB.
Thus an RTL-SDR might be able to simultaneously see both your desired signal and a spur (or harmonic) that is 43dB down,
but you will have to set up your step attenuator just right for them both to fit into the 7 bits.  Trying to measure a spur that
is 50 dB down with a device using an 8 bit ADC is totally doomed.  However, an RTL-SDR is good enough to catch
the really bad cases, there have been reports of uBitx spurs and harmonics that are only 30dB down.

Asking a friend to check for spurs and harmonics is unlikely to be very thorough.
The emissions will vary with each band you use, and to some degree as you move across the band.
The spurs can be most anywhere, your friend would have to scan the entire HF spectrum.
This sort of check is best carried out with a spectrum analyzer,
using a communications receiver will be very time consuming if you want to do a good job of it.

I'd recommend at least Raj's fix of replacing L5,L7 with his specific shielded inductors (easy!)
and replace the relays at KT1,KT2,KT3 with axicom, no sockets.  (Tough to remove.)
Alternately, instead of replacing the relays, could use an external low pass filter appropriate for each band
in line with the antenna.   Do not goose the mike gain to get more power out.
Then the rig is mostly compliant with the US -43dBc spec

I haven't heard any reports of any of these rigs attracting legal attention, even without mods..
But I would not consider using a uBitx with an external linear amp without an awful lot of work
on the uBitx first.

Jerry, KE7ER



On Tue, Jan 15, 2019 at 06:25 AM, Evan Hand wrote:
I go the relays at Mouser:
https://www.mouser.com/ProductDetail/te-connectivity/v23105a5403a201/?qs=Nk6ydC%2fJI6we9mx5p4DWfg%3d%3d&countrycode=US&currencycode=USD

I believe you can do better on price if you go through ebay, though the lowest cost may take awhile in shipment.

I am not sure that I would trust my RTL-SDR to accurately measure for the harmonics/spurs.  I got different results when compared to my RF Explorer WSUB1G+, and the front end of the RTL-SDR seems to overload easily, giving strange results.  Again, I am not sure which one to believe.  They both do agree that there is a 3rd order harmonic at 21mhz that is higher than the -43db that is required in the US.

I would also read the following threads:
https://groups.io/g/BITX20/message/61256
https://groups.io/g/BITX20/topic/27001748#61457
https://groups.io/g/BITX20/topic/28049653#61551

There are more and the net of all of this is that there is not total agreement on the fixes that are required.

My interpretation is as follow (please understand that I am NOT and expert.  I have just read a LOT of the emails related to the uBitx)
1 - The relay replace is minimum and may not totally fix the harmonic issues.  The true fix is an external low pass filter board linked to the uBitx switching relays, or possible loss in receiver sensitivity if left in and manually switched when the band is changed.

2 - If you can fix the harmonics, then operation on bands 20m and lower in frequency  should not have the IMD issue.  You can reduce that with both Ashhar's and Raj's fixes combined.

3 - without the major modifications that are suggested by the v5 board changes, the v4 and earlier should NOT be used as the exciter to a PA, UNLESS you have the equipment and skill to verify the spurious radiation is under control.

I have been told in this group that in the "old days" spurious emissions where tested using another receiver located far enough away to not overload the front end.  In other words, have a friend that can hear your signal verify no spurious emissions.  This would involve scanning for them.  I am sure that was state of the art then, not sure the FCC would agree now.  We are responsible for our transmissions.

It has also been pointed out that with the normal power levels of the uBitx, that as long as you were close, the spurs would be so far down that it would not really cause interference or be noticed.  One of the reasons for me abandoning the PA until I know what to do to the uBitx.

As always, take my input with a grain of salt.
73
Evan
AC9TU

Re: low output only on 40m

Ted
 

Yes, I reported this symptom a week or two ago and was told something to the effect of, "wiggle the torroid chokes around a bit, they're not embedded in stone" or some such.  No resolution as of yet, and I'm working on a greater problem at present [ something stupid I did, while looking at the aforementioned as it haopens]  and I look forward to anything you hear about this where where to look. Good luck.

Ted
K3RTA

Re: Tracing receive signal for low signal

Jack, W8TEE
 

 Interesting. I checked the one-price for the relay at Digikey, Mouser, Arrow, and Newark and all but Arrow were the identical price, $2.81. Arrow is $2.67. I've been pleased with Arrow in terms of prices, service, and low shipping costs (sometimes, zero).

Jack, W8TEE

On Tuesday, January 15, 2019, 9:25:48 AM EST, Evan Hand <elhandjr@...> wrote:


I go the relays at Mouser:
https://www.mouser.com/ProductDetail/te-connectivity/v23105a5403a201/?qs=Nk6ydC%2fJI6we9mx5p4DWfg%3d%3d&countrycode=US&currencycode=USD

I believe you can do better on price if you go through ebay, though the lowest cost may take awhile in shipment.

I am not sure that I would trust my RTL-SDR to accurately measure for the harmonics/spurs.  I got different results when compared to my RF Explorer WSUB1G+, and the front end of the RTL-SDR seems to overload easily, giving strange results.  Again, I am not sure which one to believe.  They both do agree that there is a 3rd order harmonic at 21mhz that is higher than the -43db that is required in the US.

I would also read the following threads:
https://groups.io/g/BITX20/message/61256
https://groups.io/g/BITX20/topic/27001748#61457
https://groups.io/g/BITX20/topic/28049653#61551

There are more and the net of all of this is that there is not total agreement on the fixes that are required.

My interpretation is as follow (please understand that I am NOT and expert.  I have just read a LOT of the emails related to the uBitx)
1 - The relay replace is minimum and may not totally fix the harmonic issues.  The true fix is an external low pass filter board linked to the uBitx switching relays, or possible loss in receiver sensitivity if left in and manually switched when the band is changed.

2 - If you can fix the harmonics, then operation on bands 20m and lower in frequency  should not have the IMD issue.  You can reduce that with both Ashhar's and Raj's fixes combined.

3 - without the major modifications that are suggested by the v5 board changes, the v4 and earlier should NOT be used as the exciter to a PA, UNLESS you have the equipment and skill to verify the spurious radiation is under control.

I have been told in this group that in the "old days" spurious emissions where tested using another receiver located far enough away to not overload the front end.  In other words, have a friend that can hear your signal verify no spurious emissions.  This would involve scanning for them.  I am sure that was state of the art then, not sure the FCC would agree now.  We are responsible for our transmissions.

It has also been pointed out that with the normal power levels of the uBitx, that as long as you were close, the spurs would be so far down that it would not really cause interference or be noticed.  One of the reasons for me abandoning the PA until I know what to do to the uBitx.

As always, take my input with a grain of salt.
73
Evan
AC9TU

Re: Tracing receive signal for low signal

Evan Hand
 

I go the relays at Mouser:
https://www.mouser.com/ProductDetail/te-connectivity/v23105a5403a201/?qs=Nk6ydC%2fJI6we9mx5p4DWfg%3d%3d&countrycode=US&currencycode=USD

I believe you can do better on price if you go through ebay, though the lowest cost may take awhile in shipment.

I am not sure that I would trust my RTL-SDR to accurately measure for the harmonics/spurs.  I got different results when compared to my RF Explorer WSUB1G+, and the front end of the RTL-SDR seems to overload easily, giving strange results.  Again, I am not sure which one to believe.  They both do agree that there is a 3rd order harmonic at 21mhz that is higher than the -43db that is required in the US.

I would also read the following threads:
https://groups.io/g/BITX20/message/61256
https://groups.io/g/BITX20/topic/27001748#61457
https://groups.io/g/BITX20/topic/28049653#61551

There are more and the net of all of this is that there is not total agreement on the fixes that are required.

My interpretation is as follow (please understand that I am NOT and expert.  I have just read a LOT of the emails related to the uBitx)
1 - The relay replace is minimum and may not totally fix the harmonic issues.  The true fix is an external low pass filter board linked to the uBitx switching relays, or possible loss in receiver sensitivity if left in and manually switched when the band is changed.

2 - If you can fix the harmonics, then operation on bands 20m and lower in frequency  should not have the IMD issue.  You can reduce that with both Ashhar's and Raj's fixes combined.

3 - without the major modifications that are suggested by the v5 board changes, the v4 and earlier should NOT be used as the exciter to a PA, UNLESS you have the equipment and skill to verify the spurious radiation is under control.

I have been told in this group that in the "old days" spurious emissions where tested using another receiver located far enough away to not overload the front end.  In other words, have a friend that can hear your signal verify no spurious emissions.  This would involve scanning for them.  I am sure that was state of the art then, not sure the FCC would agree now.  We are responsible for our transmissions.

It has also been pointed out that with the normal power levels of the uBitx, that as long as you were close, the spurs would be so far down that it would not really cause interference or be noticed.  One of the reasons for me abandoning the PA until I know what to do to the uBitx.

As always, take my input with a grain of salt.
73
Evan
AC9TU