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Re: More testing on PA
Greg
You are correct very easy to over drive 160-80M. I tried lowering input but 6m really suffered.
I changed a lot of caps across input to t3 with lower drive but just could not get 6M close.
I started taking turns off L2 which started at 6uH. Tried the cap switching on each turn I removed, kept getting better.
Ended up with 3uH and 68pF cap across primary. -2dB input. I had the high gain on low bands building a 2kw LDMOS amp.?
A friend came up with a attenuator tuned for .5-1.4 Mhz I installed on input. I believe we can compensate with carful drive input tuning on T41. Tim W4YN
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Re: RA8875 display problems with T4.x - a visual study
Yep... Jack, W8TEE
On Monday, April 7, 2025 at 01:38:51 PM EDT, K9HZ <bill@...> wrote:
Yes the T41 radio was designed as a prototype(e-ing) platform.? If you make the base radio better for your desires with your changes, that¡¯s excellent.? That¡¯s what it¡¯s about. ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Monday, April 7, 2025 12:26 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] RA8875 display problems with T4.x - a visual study ? What happened here is a series of rapid prototypes with incremental improvements.? I've got working hardware and software.? Forwards not backwards! ? -- 73 Greg KF5N -- Jack, W8TEE |
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Re: RA8875 display problems with T4.x - a visual study
¿ªÔÆÌåÓýYes the T41 radio was designed as a prototype(e-ing) platform.? If you make the base radio better for your desires with your changes, that¡¯s excellent.? That¡¯s what it¡¯s about. ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Monday, April 7, 2025 12:26 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] RA8875 display problems with T4.x - a visual study ? What happened here is a series of rapid prototypes with incremental improvements.? I've got working hardware and software.? Forwards not backwards! ? -- 73 Greg KF5N |
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Re: boards and kits and stuff
¿ªÔÆÌåÓýI¡¯m back for a while and working on kits again.? I put a very high priority on the new Display Driver board that fixes the T41 display freeze issue and allows a nice long cable to the display.? I offer a 3.3V ONLY kit and a 3.3V and 5V kit (until I run out of 3.3V kits¡ then I will only stock the combo 3.3V and 5V kit).? ??I¡¯m still writing the assembly manual for the display kits but it should be done by this afternoon.? I will order the last few parts for them today¡ I should have them by Tuesday and will begin shipping them then.? Also new to the list is the 20W Dummy Load/ 40 db attenuator tap for the calibration steps.? I¡¯ve attached the full list so you can look it over if you need something.?? Those boards and Kits with $0.00 are not in stock.? Remember, don¡¯t send me money, I¡¯ll invoice you¡ and make SURE you include your address.? All prices below are without shipping, taxes, and Paypal fee.? ? I will be at FDIM Thursday night¡ and have a booth at Hamvention (Booth 4111 in Building 4) where we will have a special guest¡ Al Peter to show off the T41 and answer any questions.? I will be selling boards and kits both places and you won¡¯t have to pay shipping on them if you carry them away. ? Respond via my private email bill@... as to not clog the space here with our transactions. ? ? ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Duane B via groups.io
Sent: Monday, April 7, 2025 11:57 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] boards and kits and stuff ? Hi Bill. ? I'm new to the group and wanted to know if it is too late to get a set of boards?? If not, how much are they? ? 73, K5CA - Duane |
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Re: RA8875 display problems with T4.x - a visual study
¿ªÔÆÌåÓýSo Greg why don¡¯t you go back and read the emails that went between Al, me, you, et al on this subject¡? instead of trying perform revisionist history. ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Monday, April 7, 2025 11:36 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] RA8875 display problems with T4.x - a visual study ? So my T41-2 radio can easily receive a Tiny SA set to the minimum output of -115 dBm.? The signal can be easily heard from the speaker and seen in the spectral display on all bands. It uses the same SPI driver device as V10/V11. ? I believe Alain is also using the same SPI buffer.? The point is, it's not a single thing which makes or breaks EMI and the noise floor.? It's a combination of design attributes.? It's almost certain that V12 could have used the same SPI buffer as V10/V11, and with the various changes like the 4-layer boards, it would have worked just fine.? And without anyone complaining about the display functionality! ? I'm getting some new attenuators and other stuff and I will be able to improve the accuracy of my measurements soon. ? -- 73 Greg KF5N |
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Re: RA8875 display problems with T4.x - a visual study
¿ªÔÆÌåÓýOk so it¡¯s not really a V11 radio. ? Did you measure sensitivity the same way I did?? The trouble with this measurement is that we need a standard to compare against. ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Alain via groups.io
Sent: Monday, April 7, 2025 10:46 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] RA8875 display problems with T4.x - a visual study ? I just measured a sensitivity of -134dbm on my V11 version,but changed PCB routing, added a motherboard to minimize wiring, added a lot of regulators and decoupling capacitors, for having this result. |
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Re: RA8875 display problems with T4.x - a visual study
¿ªÔÆÌåÓýI said it¡¯s BELOW -100 db.? After that I start measuring the noise from the fluorescent lights in the room and my wife won¡¯t let me turn them off (her glass lab is in there too).? I do have a combo anechoic/ Faraday box in corner in my lab but it¡¯s in the process of getting moved to a different corner due to new flooring and paint. ? I¡¯ll get some absolute numbers once I get some of these human things settled. ? ? 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@... ? ? From: [email protected] <[email protected]> On Behalf Of Greg KF5N via groups.io
Sent: Monday, April 7, 2025 9:15 AM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] RA8875 display problems with T4.x - a visual study ? So I think what you are saying is a standard receiver sensitivity measurement which the ARRL calls "MDS" (minimum discernible signal). Receiver sensitivity is specified in dBm, which is decibels relative to 1 milliwatt (0 dBm). ? But even if I'm not confused on that, I'm still confused with the numbers, especially 100 dB for V12, which is presumably (what I think you mean) a sensitivity of -100dBm. Which is not very good at all! ? -- 73 Greg KF5N |
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Re: RA8875 display problems with T4.x - a visual study
Ken: If you're like me, you order "pairs" of mpu's "just in case"...it's saved my bacon more than once. Anyway, I'm not sure it's worth $10. If I use just the 4.1, I tie up about $65 for backups. If I use both the 4.0 and 4.1, I'd tie up $111 ($65 + $46). It would be interesting to see if there's a performance improvement, however. The other alternative that sounds interesting is to use an RP with its HDMI video capability for the display. It's plenty fast enough, but I know nothing about programming them, the IDE, or the library support. Jack, W8TEE
On Monday, April 7, 2025 at 08:39:11 AM EDT, ken WA2MZE <wa2mze@...> wrote:
Circuit and sw details on splitting the functions over two processors? Maybe one of the mcu's could be a T4.0 to save some bucks? -- Jack, W8TEE |
jjpurdum
K9HZ