My Flex 6400 has found a new home.
Jack, W8TEE -- Jack, W8TEE
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So you probably want to characterize the gain (loss) from the antenna input on the LPF to TP6 of the RF board since we specifically put U2 in to overcome the loss from the BPF and the attenuator on the RF board¡? That is the gain that you would calibrate out for the s-meter. ? ? 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: Monday, March 10, 2025 6:22 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] Transmit attenuator? The insertion loss of the attenuator chip when set to 0dB is roughly 2dB below 20 MHz and increases at higher frequencies, so the loss you're seeing is expected. See this plot of the receive attenuator insertion loss vs frequency and attenuation setting -- the transmit path should be the same. On Monday, March 10th, 2025 at 10:38 AM, John G0SDF via groups.io <jatkins295@...> wrote:
The transmit attenuator is working in that the amount of attenuation is able to be adjusted by the setting in the Menu. However at the 0dB attenuation setting I am getting -3dB. I have a 50 ohm load on RF_OUT (J6) on the RF Board. I am testing this on CW and the peak to peak signal (ignoring overshoot) going into the attenuator chip (U12) is 980mV but the peak to peak signal out is only 696mV. Has anyone else measured the performance of the transmit attenuator?
?
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The insertion loss of the attenuator chip when set to 0dB is roughly 2dB below 20 MHz and increases at higher frequencies, so the loss you're seeing is expected. See this plot of the receive attenuator insertion loss vs frequency and attenuation setting -- the transmit path should be the same.
On Monday, March 10th, 2025 at 10:38 AM, John G0SDF via groups.io <jatkins295@...> wrote:
The transmit attenuator is working in that the amount of attenuation is able to be adjusted by the setting in the Menu.
However at the 0dB attenuation setting I am getting -3dB. I have a 50 ohm load on RF_OUT (J6) on the RF Board.
I am testing this on CW and the peak to peak signal (ignoring overshoot) going into the attenuator chip (U12) is 980mV
but the peak to peak signal out is only 696mV.
Has anyone else measured the performance of the transmit attenuator?
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Re: LPF-Control PCB TX Logic at U3 & U7
Cool!
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 Mar 10, 2025, at 9:51?AM, D Solt via groups.io <davesolt@...> wrote:
? Thanks to all for the help.? I was misunderstanding the signal path, thinking that the BPF was out of the signal path during transmit.? My T41 is working with several watts out!? Now to finish calibrating.
dave, n3ds When TX_BPF_SEL is LOW, then RF2 is selected on U3 and U7 (BPF is bypassed for the TX path). When TX_BPF_SEL is HIGH, then RF1 is selected and the BPF is placed in the path.
|
U3 |
U7 |
| TX_BPF_SEL |
Pin 6/A |
Pin 4/B |
RFC ¡ú |
Pin 6/A |
Pin 4/B |
RFC ¡ú |
| 0 |
0 |
1 |
RF2 |
0 |
1 |
RF2 |
| 1 |
1 |
0 |
RF1 |
1 |
0 |
RF1 |
On Sunday, March 9th, 2025 at 5:37 AM, John G0SDF via <jatkins295= [email protected]> wrote:
According to the data sheet this is correct, selecting the BPF for transmit sets TX_BPF_SEL high resulting in a high on pin 6 of U3 which in turn connects RFC to RF1 which is the BPF connector. So no should not connect to RF2.
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Look at Oliver, sportin' V066.7?
Go Oliver!
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Hi Bill-
?
That is a bit of roll-off in the baseband circuitry which follows the QSD (quadrature sampling demodulator).
That's a trade-off when using the demodulator for both demodulation and as a panadapter.
?
--
73 Greg KF5N
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Re: LPF-Control PCB TX Logic at U3 & U7
Thanks to all for the help.? I was misunderstanding the signal path, thinking that the BPF was out of the signal path during transmit.? My T41 is working with several watts out!? Now to finish calibrating.
dave, n3ds
When TX_BPF_SEL is LOW, then RF2 is selected on U3 and U7 (BPF is bypassed for the TX path). When TX_BPF_SEL is HIGH, then RF1 is selected and the BPF is placed in the path.
|
U3 |
U7 |
| TX_BPF_SEL |
Pin 6/A |
Pin 4/B |
RFC ¡ú |
Pin 6/A |
Pin 4/B |
RFC ¡ú |
| 0 |
0 |
1 |
RF2 |
0 |
1 |
RF2 |
| 1 |
1 |
0 |
RF1 |
1 |
0 |
RF1 |
On Sunday, March 9th, 2025 at 5:37 AM, John G0SDF via <jatkins295= [email protected]> wrote:
According to the data sheet this is correct, selecting the BPF for transmit sets TX_BPF_SEL high resulting in a high on pin 6 of U3 which in turn connects RFC to RF1 which is the BPF connector. So no should not connect to RF2.
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Need to calibrate it. ?Its not absolute.?
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 Mar 10, 2025, at 7:38?AM, John G0SDF via groups.io <jatkins295@...> wrote:
? The transmit attenuator is working in that the amount of attenuation is able to be adjusted by the setting in the Menu.
However at the 0dB attenuation setting I am getting -3dB. I have a 50 ohm load on RF_OUT (J6) on the RF Board.
I am testing this on CW and the peak to peak signal (ignoring overshoot) going into the attenuator chip (U12) is 980mV
but the peak to peak signal out is only 696mV.
Has anyone else measured the performance of the transmit attenuator?
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Good morning Greg,
Last night was able to get the T41-2 main board/qse2/qsd2 combination working in what was originally a 4SQRP T-41k. (so far just on receive)
I noticed that the right side of the waterfall display seemed to be more sensitive than the left. When I looked at the google drive pictures of your radio posted on this thread, I noticed the same effect. I am curious as to the reason for this.
73 Bill NX5AA
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The transmit attenuator is working in that the amount of attenuation is able to be adjusted by the setting in the Menu.
However at the 0dB attenuation setting I am getting -3dB. I have a 50 ohm load on RF_OUT (J6) on the RF Board.
I am testing this on CW and the peak to peak signal (ignoring overshoot) going into the attenuator chip (U12) is 980mV
but the peak to peak signal out is only 696mV.
Has anyone else measured the performance of the transmit attenuator?
|
And this is what i get when i text on my phone at 5 AM¡
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 Mar 10, 2025, at 6:34?AM, K9HZ <bill@...> wrote:
? With the replacement of the follower and filter op amps post mixer, i see about a 7db improvement and at that point i believe the limit is the mixer, si 5351, and line shielding between the. ?We are in some stellar class radios at this point. ?Im very happy with the way this has turned out. ?
The QST review of the IC-7300 was madd public by icom so i may post that in the files section as a stick to compare against. ?
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@... ? On Mar 10, 2025, at 3:41?AM, Oliver KI3P via groups.io <oliver@...> wrote:
? Greg, I get a very similar number for the noise floor (-131 dBm) if I tune away from the display noise, so the V12 hardware is capable of achieving similarly low noise floors if you can fix the display noise. Hopefully folks who have solved this can share their stories of success for the rest of us to learn from.
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With the replacement of the follower and filter op amps post mixer, i see about a 7db improvement and at that point i believe the limit is the mixer, si 5351, and line shielding between the. ?We are in some stellar class radios at this point. ?Im very happy with the way this has turned out. ?
The QST review of the IC-7300 was madd public by icom so i may post that in the files section as a stick to compare against. ?
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 Mar 10, 2025, at 3:41?AM, Oliver KI3P via groups.io <oliver@...> wrote:
? Greg, I get a very similar number for the noise floor (-131 dBm) if I tune away from the display noise, so the V12 hardware is capable of achieving similarly low noise floors if you can fix the display noise. Hopefully folks who have solved this can share their stories of success for the rest of us to learn from.
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Greg, I get a very similar number for the noise floor (-131 dBm) if I tune away from the display noise, so the V12 hardware is capable of achieving similarly low noise floors if you can fix the display noise. Hopefully folks who have solved this can share their stories of success for the rest of us to learn from.
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Mark, I don't see the disappearing audio issue in the beta version of the code (V66-7) that I'm testing, so it's been fixed. It'll come out soon; Al has rewritten the calibration routines and added SWR calibration and readout, and a few of us are testing it and squashing bugs.
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Great! ? ? 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 epif18 via groups.io
Sent: Sunday, March 9, 2025 5:31 PM
To: [email protected]
Subject: Re: [SoftwareControlledHamRadio] Excessive Noise? Wow, significantly better.? V066.1, no cal performed.? Pulsating noise is gone.? This is just a first look (really just a peek), still need to check things out.? One thing I notices is that after I TX in SSB mode, the signal is then gone (spectrum and audio out) in RX mode (signal from sig gen, -50dbm).? Also, SSB TX Audio is not displayed.? I fixed that one in 50.2, I'll try the same in this version. Thanks for all the hard work.
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The Pulsing went away with 66 on my build, seems I saw those on 20M but I believe they are gone or diminished with the ferrite sleeves on ribbon cables.
Mine? is apart while I wrap up PA testing and eventually rewind the BPF's (please don't ask :(? )
I will post some snap shots later this week.
Tim W4YN
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Here's the T41-2 which uses the QSD2, a revised version of the original V11 board:
?
The signal is from a TinySA set to the lowest it will go, which is -115 dBm.? The S-meter calibration was done at -73dBm.
So the dBm reading is off a few dB, but considering this is not a true RF measurement, it's amazingly close.? The S-meter and dBm readout
was updated by Joerg DB2OO a while back.? The signal is easily audible in the speaker.
?
Here is with the tuning bar offset so you can see the signal in the spectrum a little better:
?
The Main board is T41-2.? This is a heavily revised version of the original V11 design.? It still has the original display driver IC for the SPI bus.
It's not any annoying noise in this band.? All in 3D printed plastic case and no shielding or grounding.
?
--
73 Greg KF5N
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Wow, significantly better.? V066.1, no cal performed.? Pulsating noise is gone.? This is just a first look (really just a peek), still need to check things out.? One thing I notices is that after I TX in SSB mode, the signal is then gone (spectrum and audio out) in RX mode (signal from sig gen, -50dbm).? Also, SSB TX Audio is not displayed.? I fixed that one in 50.2, I'll try the same in this version.
Thanks for all the hard work.
Mark
KU3O
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Thanks Bill.? I'll download it today and let yall' know.
Mark
KU3O
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Thanks Oliver.? This will be extremely helpful.
Mark
KU3O
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jjpurdum
K9HZ
Tom - AJ8X