The T41 design was a compromise on several fronts ¨C primarily price vs performance., hence the situation with the power out.
?
T41 is designed to be a teaching tool with flexibility and modularity. At the time we designed the PA, RF power transistors like the RD16HH were quite expensive and had limited availability. We did not feel that the price point with the extended frequency range at 20W suited our cost goals, hence the reduced power at 10M. T41 is meant to be QRP+, so some reduction of the higher end was the compromise to keep the price point down. We consciously made the decision to go with the less expensive output transistor design, knowing that the RF PA could easily be changed out if desired.
?
By the way, the T41 costs several hundred dollars, not the many times higher price of ICOM or other commercial rigs. The popular ICOM 7300 goes for $1100 vs T41 at about $350.)
?
That situation has changed somewhat, with the availability of $4 RD16HHs, making a redesign possible. Four years makes a difference. The K9HZ 20W amp is rated for 15W RMS and over 20W PEP, and it suits many builders. It is especially attractive for those who might wish to drive an external Linear.
?
I personally also like the performance of the 20W K9HZ amp. It is alos pretty much indestructible. ?On the other hand Jack and I have made numerous contacts with the original T41 amp with excellent signal reports.
?
We aim to provide choices.
Regards,
?
Al
AC8GY
?
From: K9HZ
Sent: Saturday, October 7, 2023 7:07 PM
To: [email protected]
Subject: Re: [AmateurRadioBuilders] [SoftwareControlledHamRadio] V010 vs V011
?
Thanks Dave.? Yep, that little thing is a real gem.? I designed and built it because I just can¡¯t stand hobby-ish radios that put out 40 watts on 7 MHz, and then 3 watts on 28 MHz.? It just means the designer didn¡¯t care enough about his design to make it wide-banded¡ or didn¡¯t know enough about RF design to make it happen.? Can you imagine what would happen if your brand new ICOM radio did that?
?
?
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@...
?
?
?
Bill, this week I assembled two of the 20Wt amplifiers and they work great.? I was sweeping them at about 5watts with my NanoVNA and a 49dB attenuator (calibrated nano with the attenuator chain). I measure 48.6dB gain at 3.5MHz, 47.9dB at 7MHz, 47.8dB at 30MHz, and 43.7dB at 54MHz.? I am running with no filtering and see a lot of harmonic content at high frequency after adding C24 at 100pF (added to boost high freq performance), so I don't think I am seeing a 3dB roll off at 50MHz.? Thank you for you work on this.? I look forward to the v12 boards.
I will start next week on programming the Teensy4.1 and connecting it to the display.
?
On Sat, Oct 7, 2023 at 12:32?PM K9HZ <bill@...> wrote:
I also have a conference this week in Denver so things will pause for a few days on my end. ? I did send schematics to Al to review yesterday though so trying to multitask and get stuff out ASAP. ?
I did receive an order of 20W PA boards yesterday ?so those are back in stock. ?
?
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:
?
email:??bill@...
?
?
> Once the boards are finalized and I can get the Gerbers
> I will start getting boards made for UK and Europe.
And, for our Canadian hams...? Once the new boards are finalized and available from K9HZ, I'm happy to offer to import and distribute them in a new round.
I'll also be away for a work conference for the next week ( I plan to sneak out to get a couple POTA activations in though, so look for VA3NCA/W9 on spots) so probably won't be very quick to reply, but I will start collecting item orders and quantities once Bill's ready, and I'm back and caught up after travel ?
-------- Original message --------
Date: 2023-10-07 10:01 a.m. (GMT-05:00)
Subject: Re: [SoftwareControlledHamRadio] V010 vs V011
Once the boards are finalized and I can get the Gerbers I will start getting boards made for UK and Europe.
I am in Dubrovnik for the next few days but once I have them I can get started straight away.
?
On Sat, 7 Oct 2023, 15:31 K9HZ, <bill@...> wrote:
I started sending final production schematics to Al as of last night.? It wont be long.? A few things left to resolve on the RF board and we can go into production. ?
?
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:
?
email:??bill@...
?
?I can give you some ideas.
I know several people worked on the project is small steps as I did.
First, buy the Teensy 4.1 and the display.? Using a breadboard and a power supply, you can connect the Display to the Teensy and load the software.
Setting up the IDE and the libraries and getting the Teensy properly programmed and the display working is a major step.? Getting the Display delivered may take weeks.
Next I would build and test the power supply board, and then the Main board.? Now see if the Teensy in the Main board successfully drives the display.
Build the Switch Matrix board, which is easy, and connect to the Main board and see if you can get past the switch matrix calibration.
Also another huge step is getting the 3D printed case built and assembled.
Regarding the BOMs, what we did in the early days was collaborate quite a lot in the discussions here to get the correct parts.? There are errors in the published BOMs, and also
parts which are no longer available and need substitutes.
4SQRP should be publishing their BOMs soon, and they should be quite accurate, being adjusted for the current supply chain issues.
Another idea would be to proceed through the breadboading of the display and IDE setup and programming, at which time the V012 boards could become available.
I don't know the current schedule for that to happen, but I do know it will take you a while just to get to the working breadboard stage.
--
73 Greg KF5N
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