On 2025-02-25 10:30, rebruhnke via groups.io wrote:
Last evening, I finally got my version of the T41 on the air for an
extended period of time on 75M. Talked all over the US and even down
to British Honduras with my home brew amp running about 800W.
*** Very cool, Russ. What sort of homebrew amp are you using?
I use my T41 with an amp with an MRF1K50 - RF card & LPF kits from W6PQL,
a Chinese cell-phone-surplus rack mount power supply, a 4-inch touch screen
driven by a Teensy 4.1 with software I wrote.
We do 800-1100W, and reports have been universally good.
I didn't use the amp with my V11 system; I didn't think it was clean enough.
But with Bill's BPF, the V12 is good to go.
- Jerry, KF6VB
I call it the "Franken" T41 because the RF portion is not a T41. This
is my FPGA implementation with a DSPic CK doing the actual
demodulation/modulation. Sensitivity is such that I can hear a -127dB
signal; low, but it is there. On all bands the antennas generate way
more noise than the rig. The FPGA splits the RF signal two ways: One
set to a DAC for the panadapter and one set to the DSPic via I2S.
Other than the panadapter signals, all analog "audio" is at
high-level. No calibration is needed; the beauty of getting to digital
as soon as possible.
The UI is run by the Teensy using much of Al and Jack's code for noise
reduction and equalization displaying on a 7" capacitance touch screen
using an 8bit bus. The panadapter only displays +/- 48K as I like that
display format the best. The display is not the ones used in the T41
as the capacitance touch "areas" of those displays are much larger
than the one I am using and I need that resolution. No buttons on the
front panel. Touch panel handles all "buttons" including band and mode
changes.
CW keying is crisp and the rise/fall times are handled totally via
software in the DSPic. Built-in Iambic keyer.
I'll get some internal pics up later today.
I should receive a PCB today that has the Teensy in place of the
DSPic... Next project and we'll see how that goes.
I am using Bill's BPF, LPF and control board. The control board is
modified slightly to provide for a receive antenna so I can attach my
Beverage. The BPF is only on the RX path as my transmitter is squeaky
clean before the 100W PA. The PA board is one I got from Glenn, VK2PE
many moons ago for another project.
I want to thank Al and Jack for putting this out in the public domain
and for Bill and Oliver doing the boards. I get great compliments on
the audio and the cleanliness of my signal.
Russ NQ0U
Links:
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[1] /g/SoftwareControlledHamRadio/message/32930
[2] /mt/111382384/243852
[3] /g/SoftwareControlledHamRadio/post
[4] /g/SoftwareControlledHamRadio/editsub/243852
[5]
/g/SoftwareControlledHamRadio/leave/10484476/243852/1943518115/xyzzy
