I am getting about 50mv noise out of the 20W amp in SSB with PTT engaged; no mic plugged in.? I'm running version 66.9 and am all calibrated.? Additionally, when PTT is engaged there is a burst of signal (about500mv) that exponentially decays in 5ms.? The audio sounds pretty rough on my other radio, but wonder if that is because of such close proximity.? Amplitude is affected by MIC GAIN.? Any thoughts?
dave, n3ds
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Re: [AmateurRadioBuilders] Updated (and final) Version of T41 book
Our booth at Hamvention is inside this year¡ 4111 in building 4. ?You can buy the lasted and greatest T41 boards and kits along with everything else I sell there. ?Plus we will be advertising the contest station for rent. ??
My wife was tired of being out in the rain and the smell of the porto-pottys in the outfield. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Apr 4, 2025, at 12:33?PM, Albert Peter via groups.io <albertfpeter@...> wrote:
?
Robert and everyone attending the Hamvention:
I will probably be at K9HZ's booth in one of the buildings on Friday and Saturday. I will have some signed T41 books available at that time. Get there early, since I will only have a limited number of books.
(Jack probably will not be there at Hamvention.)
Bill Schmidt will also has T41 V12 board set available .
Hope to see you there.
Al Peter
AC8GY
Jack, is there a way to get an autographed copy of Version 4, since I can't make it to the FDIM conference?
On 4/4/2025 10:53 AM, Jack, W8TEE via groups.io wrote:
All:
Al and I have just updated the 3rd edition T41 book. We moved the calibration info from Appendix C to its own chapter (20). The expanded instructions and new software make T41 calibration much easier. We have also updated
the narrative in numerous places and have concentrated discussions on the V12.6 release where those changes are important.
Some of you are asking yourself: Do I need to buy this update. Truthfully, if you already own the 3rd edition, we would say no. Most of the important changes are discussed on the web site and photos and schematics are
available there, too.
On the other hand, this is the last change we will be making to this book. Al and I have been at this for almost 7 years now and we're getting a little burned out. For that reason, we are turning this site over to Oliver King, KI3P,
and Dr. Bill Schmidt, K9HZ. Al and I will continue to be active relative to the T41, but will leave the details to Oliver and Bill.
If you do want the final version of the book, its new cover looks like this:
The book is actually available now, but the Amazon ad will not reflect the new cover for about 10 more days. (If you order now, it will be the new version.) If you are attending the FDIM conference this May (coincides with Dayton Hamvention and the conference
hotel is about 10 miles away), Al and I will be selling autographed copies on Thursday night (May 15th) at the conference hotel starting around 8PM. We have reduced the price of the autographed copies from $12,500 to $40...which is a deal and less
than the Amazon price! If you have a previous copy of the book, bring it along and we will be happy to sign it.
This has been a fun project and we want to thanks the hundreds of people have contributed to its improvement over time. We hope that continues long after Al and I are gone.
72,
Jack Purdum, W8TEE
Al Peter, AC8GY
--
Jack, W8TEE
--
73 
Bob W3RDL
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Updated (and final) Version of T41 book
All:
Al and I have just updated the 3rd
edition T41 book. We moved the calibration info from Appendix C to
its own chapter (20). The expanded instructions and new software make
T41 calibration much easier. We have also updated the narrative in
numerous places and have concentrated discussions on the V12.6
release where those changes are important.
Some of you are asking yourself: Do I
need to buy this update. Truthfully, if you already own the 3rd
edition, we would say no. Most of the important changes are discussed
on the web site and photos and schematics are available there, too.
On the other hand, this is the last
change we will be making to this book. Al and I have been at this for
almost 7 years now and we're getting a little burned out. For that
reason, we are turning this site over to Oliver King, KI3P, and Dr.
Bill Schmidt, K9HZ. Al and I will continue to be active relative to
the T41, but will leave the details to Oliver and Bill.
If you do want the final version of the
book, its new cover looks like this:
The book is actually available now, but
the Amazon ad will not reflect the new cover for about 10 more days.
(If you order now, it will be the new version.) If you are attending
the FDIM conference this May (coincides with Dayton Hamvention and
the conference hotel is about 10 miles away), Al and I will be
selling autographed copies on Thursday night (May 15th) at
the conference hotel starting around 8PM. We have reduced the price
of the autographed copies from $12,500 to $40...which is a deal and
less than the Amazon price! If you have a previous copy of the book,
bring it along and we will be happy to sign it.
This has been a fun project and
we want to thanks the hundreds of people have contributed to its improvement over time. We
hope that continues long after Al and I are gone.
72,
Jack Purdum, W8TEE
Al Peter, AC8GY
-- Jack, W8TEE
|
Re: Where can I purchase V12 pc boards for the T41-EP SDT?
That would be me. ? Ill be home late tonight. ?Tell me what you are looking for exactly. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Apr 4, 2025, at 9:55?AM, rkherod via groups.io <rkherod@...> wrote:
? I am interested in purchasing the latest V12 blank pc boards for the T41-EP SDT.? Can anyone point me in the right direction to purchase these?
?
Thanks?
|
Where can I purchase V12 pc boards for the T41-EP SDT?
I am interested in purchasing the latest V12 blank pc boards for the T41-EP SDT.? Can anyone point me in the right direction to purchase these?
?
Thanks?
|
On Wed, Apr 2, 2025 at 07:48 AM, K9HZ wrote:
Dr. Bill
Playing with compensation caps around 180-220 flattens out from 3-30Mhz I can't seem to get much gain past 35-40Mhz
Still playing not that interested in 6M qrp? so not a big deal.
?
Just curious on how Paul got his so flat out to 50Mhz.
Tim?
?
?
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Re: TX sidebands reversed
That was an instant fix!
?
Thanks Rick.
?
Roger G8JWT
|
Re: TX sidebands reversed
Roger. Try a 180 deg flip of the 3 pin connector going from the audio top hat to the teensy 3 pin connector.? Worked on V11 should also work on V12. No guarantees but easy to try. Rick, KN4AIE ? ?
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From: [email protected] <[email protected]> On Behalf Of bty84827531 via groups.io
Sent: Thursday, April 3, 2025 9:54 AM
To: [email protected]
Subject: [SoftwareControlledHamRadio] TX sidebands reversed? I'm in the middle of doing the TX calibration using 66.9. On receive the radio works with the indicated sideband just fine, but when I switch to transmit the sideband is reversed. In other words when the screen says I'm on LSB the radio transmits on USB. This only affects transmit. The receiver works correctly as shown on the screen.
|
I'm in the middle of doing the TX calibration using 66.9.
?
On receive the radio works with the indicated sideband just fine, but when I switch to transmit the sideband is reversed. In other words when the screen says I'm on LSB the radio transmits on USB. This only affects transmit. The receiver works correctly as shown on the screen.
?
Any ideas anyone?
?
Roger G8JWT
|
Re: T41 Transmit Calibration V12
Thanks Oliver. On to SSB Cal tomorrow. Almost done! dave
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On Apr 2, 2025, at 4:42?PM, Oliver KI3P via groups.io <oliver@...> wrote:
? That's right Dave -- you null the lower image if you're in a USB band, and vice versa
-------- Original Message -------- On 4/2/25 2:38 PM, D Solt via groups.io wrote: When doing the TX IQ calibration of the higher bands that use USB, do you null the lower image?
dave, n3ds
|
Re: T41 T41EEE.9 Firmware Release
Very nice, Greg!
Jack, W8TEE
On Wednesday, April 2, 2025 at 08:32:00 PM EDT, Greg KF5N via groups.io <greg.electricity@...> wrote:
Demo of the new AGC in T41EEE.9:
?
?
Compressor2 is part of the Open Audio Library.? Bob's Tiny Ten Transceiver uses it in the audio data path.
This seemed to be a natural replacement for the code inherited from the SDR Convolution receiver.
I tried it, and WOW it works great!
?
The Open Audio Library:
?
Compressor2 is also used in the transmitter path along with the CESSB module.? Good stuff!
?
--
73 Greg KF5N
-- Jack, W8TEE
|
Re: T41 T41EEE.9 Firmware Release
Demo of the new AGC in T41EEE.9:
?
?
Compressor2 is part of the Open Audio Library.? Bob's Tiny Ten Transceiver uses it in the audio data path.
This seemed to be a natural replacement for the code inherited from the SDR Convolution receiver.
I tried it, and WOW it works great!
?
The Open Audio Library:
?
Compressor2 is also used in the transmitter path along with the CESSB module.? Good stuff!
?
--
73 Greg KF5N
|
Hi Oliver, you're generally right, but missing one important detail.? The harmonic copies coming out of the QSE circuitry will mix with the fundamental in the power amplifier
and produce intermodulation products (adjacent channel splatter) right along side the fundamental.? At that point, that junk can't be filtered out.? The LPF won't help.
The math of the problem kind of catches you off guard.? The harmonic energy is offset from exact harmonics, due to the modulator.? I was able to simulate this.? We were all surprised when we saw this phenomenon
in the early days of the T41.
?
So a bandpass (or lowpass) between QSE output and PA input keeps that energy out of the PA and there is no opportunity for generation of those adjacent channel intermodulation products.
?
--
73 Greg KF5N
|
Yeah exactly right¡ everyone is use to having a BPF in transmit to clean up the signal before transmitting¡. ? But what many SDRs are missing is a preselector¡ a band filter mechanism in receive that only allows the band you are listening through (Hence two BPFs for dual receive¡ because you could be on different bands).? And because SDRs (and particularly this SRD that can operate from about 400kc up to almost 150 mhz), receiving a very loud signal pretty much anywhere in its receive range can desensitize the front end/ mixer to the point that you hear nothing!? We fixed that with the BPF in the T41 operating in Receive too¡. ? So when at Field Day operating with friends on different bands¡ you won¡¯t see any interference in the receiver from them. ? That¡¯s the reason we used a 5 pole filter¡the skirts are very sharp so all the trash outside of the TX and RX frequency is greatly attenuated. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] <[email protected]> On Behalf Of Oliver KI3P via groups.io
Sent: Wednesday, April 2, 2025 4:09 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] Ver066_9_3_22_25? Bill can comment further, but the BPF should be in the signal path in both RX and TX mode.? In TX mode it cleans up the signal before it goes to the PA. This means that higher-order harmonics of the signal produced by the exciter -- copies of the signal at multiples of the transmit signal -- are filtered out and not amplified by the PA. These would be removed by the LPF anyway before they could hit the antenna, but removing them before the PA helps with signal quality because the PA isn't having to amplify signals at multiple bands simultaneously. In RX mode the BPF keeps the other bands away from the input to the mixer. If you didn't have the BPF in place you would expect to get a higher noise level in the audio at best, and distortion from strong signals in other bands at worst. On Wednesday, April 2nd, 2025 at 3:54 PM, epif18 via groups.io <epif18@...> wrote:
Well, I did some more troubleshooting and this is what I found: I stuck some troubleshooting code at the beginning (first line) of loop().? Draw a line on the display.? Well, looked like setup never exited.? Stuck that code in various places in .ino and eventually found that swrSetup() was hanging up.? I have the SWR_AD7991 installed but not the transformer (shorted RF In to RFOut). I commented #define V12_LPF_SWR_AD7991 out.? Then I commented out swrSetup() and 66.9 ran! Looks like it's not in the latest code on github (KI3P/SDTVer066-9) that was updated 2 weeks ago. I've shut down my radio and brought it back up and all is good. Still a little noisy on 40M but 20M seems to be working great. While I'm at it, when should the BPF_TX and _RX be in or out?? I attached a test cable to the LPF ACC Control connector and those signals are different moving from 66.4 to 66.9.? In 66.4, BPF_RX was out in SSB mode and in when in CW mode.? In 66.9, it appears that BPF_RX is "in" in both modes.?
?
|
Bill can comment further, but the BPF should be in the signal path in both RX and TX mode.?
In TX mode it cleans up the signal before it goes to the PA. This means that higher-order harmonics of the signal produced by the exciter -- copies of the signal at multiples of the transmit signal -- are filtered out and not amplified by the PA. These would be removed by the LPF anyway before they could hit the antenna, but removing them before the PA helps with signal quality because the PA isn't having to amplify signals at multiple bands simultaneously.
In RX mode the BPF keeps the other bands away from the input to the mixer. If you didn't have the BPF in place you would expect to get a higher noise level in the audio at best, and distortion from strong signals in other bands at worst.
On Wednesday, April 2nd, 2025 at 3:54 PM, epif18 via groups.io <epif18@...> wrote:
Well, I did some more troubleshooting and this is what I found:
I stuck some troubleshooting code at the beginning (first line) of loop().? Draw a line on the display.? Well, looked like setup never exited.? Stuck that code in various places in .ino and eventually found that swrSetup() was hanging up.? I have the SWR_AD7991 installed but not the transformer (shorted RF In to RFOut). I commented #define V12_LPF_SWR_AD7991 out.? Then I commented out swrSetup() and 66.9 ran!
?
Looks like it's not in the latest code on github (KI3P/SDTVer066-9) that was updated 2 weeks ago. ?
I've shut down my radio and brought it back up and all is good.
?
Still a little noisy on 40M but 20M seems to be working great.
?
While I'm at it, when should the BPF_TX and _RX be in or out?? I attached a test cable to the LPF ACC Control connector and those signals are different moving from 66.4 to 66.9.? In 66.4, BPF_RX was out in SSB mode and in when in CW mode.? In 66.9, it appears that BPF_RX is "in" in both modes.?
Thanks
Mark KU3O
?
|
Re: T41 Transmit Calibration V12
That's right Dave -- you null the lower image if you're in a USB band, and vice versa
-------- Original Message -------- On 4/2/25 2:38 PM, D Solt via groups.io wrote: When doing the TX IQ calibration of the higher bands that use USB, do you null the lower image?
dave, n3ds
|
Well, I did some more troubleshooting and this is what I found:
I stuck some troubleshooting code at the beginning (first line) of loop().? Draw a line on the display.? Well, looked like setup never exited.? Stuck that code in various places in .ino and eventually found that swrSetup() was hanging up.? I have the SWR_AD7991 installed but not the transformer (shorted RF In to RFOut). I commented #define V12_LPF_SWR_AD7991 out.? Then I commented out swrSetup() and 66.9 ran!
?
Looks like it's not in the latest code on github (KI3P/SDTVer066-9) that was updated 2 weeks ago. ?
I've shut down my radio and brought it back up and all is good.
?
Still a little noisy on 40M but 20M seems to be working great.
?
While I'm at it, when should the BPF_TX and _RX be in or out?? I attached a test cable to the LPF ACC Control connector and those signals are different moving from 66.4 to 66.9.? In 66.4, BPF_RX was out in SSB mode and in when in CW mode.? In 66.9, it appears that BPF_RX is "in" in both modes.?
Thanks
Mark KU3O
?
|
Re: Oscillations on high bands
Yeah you can short C14 and C16 but C15 needs to be a 0.1uf¡?? I¡¯ll fix that on the Carrier board for the PIN DIODE TR switch¡ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] <[email protected]> On Behalf Of D Solt via groups.io
Sent: Wednesday, April 2, 2025 1:28 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] Oscillations on high bands? I solved my oscillation problem.? I did not populate the 1.8MHz HPF.? I placed shorts across the capacitors forgetting that the MASWSS0179TR RF Switch needs DC blocks.? I now have >65 dB isolation across the frequency range. I am running version 66.9.
|
Re: T41 Transmit Calibration V12
When doing the TX IQ calibration of the higher bands that use USB, do you null the lower image?
dave, n3ds
|
Re: Oscillations on high bands
I solved my oscillation problem.? I did not populate the 1.8MHz HPF.? I placed shorts across the capacitors forgetting that the MASWSS0179TR RF Switch needs DC blocks.? I now have >65 dB isolation across the frequency range.
I am running version 66.9.
dave, n3ds
?
?
|
K9HZ
jjpurdum