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I've been happy with my 4SQRP T41, but I don't have much experience with this.? What's considered an "intolerable" noise level for that radio? Currently, my partially built v12 has a receiver noise

“ Bill, are you saying the T41 kits are unusable? The displays work great! ” I said no such thing. The display worked but the noise from the SPI buffer chip brought the noise level in the receiver

Greg et al: The TMPS previously had noise induced in the audio chain by the display interface when everything was managed by a single Teensy (touching the screen & changing onscreen objects caused a

Any digital bus, by its nature, is going to produce noise.? That's the physics of digital waveforms (high slopes and discontinuities).? This issue is mitigated by applying good EMI design practices

This information is incorrect. The 74HC125 was the source of horrendous noise generation in the HF band spectra when connected to the SPI bus. This is documented in the forum exchanges from fall two

Very interesting... Jack, W8TEE

Hi Mark- The T41 project has been successful with this device: https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/74HC125D/6198923 There was a run of a couple hundred kits

Just curious; do you think a piece of UTP CAT 5 or 6 would work? John, W5JSS <tmrob4@...> wrote:

Oh, build results: Memory Usage on Teensy 4.1: FLASH: code:305956, data:129336, headers:9116 ? free for files:7682056 RAM1: variables:191584, code:283272, padding:11640 ? free for local

Hey yall', I was running Ver66.9 and it seemed to address some of the issues I was having.? Calibrated FREQ and REC I/Q.? All good through several shutdowns and startups. Shut my radio down and

In the T41, there is also crosstalk on the display cable.? In the image below, the shorter ribbon cable does not work.? You need a cable of this type with about half this length to work.? The

So we designed those resistors into the V12.6 main board after reading the same posts you read… and that is what everyone has today (see the main board schematic out on my github). After a lot pf

The subject of problems with the SPI interface between the T4.x & RA8875 displays comes up quite often on the Teensy forum.? I would like to point out that the SPI interface is not anything that PJRC

In ver 50.0 in SSB and CW modes, TX_BPF_SEL and TR_BPF_SEL both switch states when PTT or Key engaged In ver 66.4 in CW mode, TX_BPF_SEL and TR_BPF_SEL both switch states when Key engaged. In SSB

Might consult Al. He may have stuck some code back in to work with the legacy V11 LPF. I recall there was some discussion of that several months ago. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ

SPI on the Teensy today is in fractions of the (600 MHz) clock speed and that can be very high (eg 50 MHZ). There is a way to set it in software but i have not experimented with it. That certainly has

SWAG is a technical term:? "Scientific Wild Ass Guess". -- 73 Greg KF5N

What is a SWAG? [email protected]> wrote:

Bill, what I was trying to get at was the *measurements* of the signal path.? The behavior versus frequency. -- 73 Greg KF5N

Since its a SWAG… explain why it happens with V69 of the software but not with V50. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch –