|
Re: FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýYeah.? That¡¯s where the ¡°DUH¡± came from¡ ? ? 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 Gordon Gibby KX4Z via groups.io
Sent: Friday, February 14, 2025 7:29 PM To: [email protected] Subject: Re: [AmateurRadioBuilders] FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? Easy to sacrifice gain to get negative feedback (and better linearity) when power isn't an issue and there is excess gain available (e.g. low power stages) ? Much more expensive and risky to add high power gain stage after high power gain stage trying to keep them at "low power" -- I don't know for sure but I worry that the phase shift at parasitic frequencies could become an issue and cause instability (would have to go back to 50 years ago to review all that....) ? The available power amplification devices we have just aren't perfectly LINEAR, and we usually don't have huge gain around to throw away in that stage.....so tough to deal with.? ? I'm guessing it is easier if we run the corrections to an ealier?stage some how that doesn't risk oscillation.? ?Certainly not an expert here.? ? But if the output becomes cleaner and we didn't have to spend a bazillion $$$, that's a good thing, right? ? Gordon KX4Z ? ? ? On Fri, Feb 14, 2025 at 7:16?PM K9HZ via <bill=[email protected]> wrote:
|
|
Re: For you designer builders...
¿ªÔÆÌåÓýI think that depends on the circumstances but yes the low noise parts make a much bigger difference. ? ? 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 glenn percy via groups.io
Sent: Sunday, February 16, 2025 7:03 PM To: [email protected] Subject: Re: [AmateurRadioBuilders] For you designer builders... ? Hi Bill Not sure how true this is but apparently LM317 style regulators are better than the LM7805's.?? Not as good as a dedicated low noise part though for sure. ? glenn vk3ep ? |
|
T41 BPF results
These are great, Oliver. If it's okay with you, could you send me the hi-rez versions of the graphs? Al and I would like to include them in the book. BTW, I tweaked the toroids in the LPF board to match their table values. As it turns out, they are very close as is. I fiddled with the turn spacing on a few, but did not have to add or subtract turns for any toroid. I've attached the table. Below is the first band in the table to illustrate what the file contains: Band Inductor Type (Core) ????Turns ???? Wire Length 160M ???? L3 ????????????T68-2 (Red) ????????30 ????????????25.00¡± ????????????? L14 ????????????T68-2 (Red) ?????? 28 ????????????23.50¡± ????????????? L25 ????????????T68-2 (Red) ????????30 ????????????25.00 The wire length is taken from the Kits and Parts table () but I changed the wire length to account for the #20 gauge wire that is suggested if you plan to use Bill's 100W PA. (The K&P table is for #26 gauge wire and the 20W PA.) I also added about an inch to each length so you have enough for generous pigtails. Alas, the Crochet Hook Method for winding cores doesn't lend itself to the heavier gauge and small core diameter. Just take your time and you'll be fine. I will also be posting the table to the SCHR site. Jack, W8TEE
On Sunday, February 16, 2025 at 02:23:34 PM EST, Oliver KI3P via groups.io <oliver@...> wrote:
?
I wound another V12 bandpass filter board to replace the prototype board in my radio. I'm pretty happy with the performance. Here are some plots showing the measured transmission curves for all the channels.
?
?
?
I measured and tweaked the inductance for every core and ended up with values that often differ from the recommended values. You can find a fill write up with all the details of the core windings and a comparison of each filter to the ELSIE simulation on my blog here:
?
Cheers,
Oliver KI3P
-- Jack, W8TEE |
|
Re: CAT Transmit
All: The final version of the code is about to be released by Al and I and we are turning it over to Oliver to care for it in the future. There are coding style differences that some people will disagree with, and that's fine. Jerry has be active in working with the code and prefers another style. What follows is my response to some of the questions he raised. ============= It is kinda a matter of choice and style. As to finding function prototypes, I have tried to maintain those alphabetically in the SDT.h header file. I've done the same for globals. The problem is that more than one person is editing the code and header file(s). Also, you landed on one of my pet peeves: the confusion between the terms "define" and "declare". They are not the same terms. You said: A class definition doesn't assign storage. That is incorrect. From the 2nd edition of the K&R C book, page 210: ??? Declarations specify the interpretation given to each identifier; they do not necessarily reserve storage associated with the identifier. Declarations that reserve storage are called definitions. The first sentence above means that a declaration creates an attribute list for each variable and stores it in the symbol table. Because declarations do not allocate storage for the variable, that attribute list will NOT contain an entry that specifies where in memory to find that variable. This memory location is called the lvalue of a variable. (What a variable contains is called the rvalue. The terms lvalue and rvalue are likely hangovers from assembly language programming for location (lvalue) and register (rvalue) concepts.) It is only after a definition of the variable that it has an lvalue that can be added to the attribute list found in the symbol table. If anyone still thinks they are the same, then have them explain the need for the C extern keyword. The extern keyword was created specifically because of the need to use a variable in one file when it is defined in another file. The data declaration in one file: ??? extern int myVariable; says to the compiler: "I know this variable is not defined in this file, but you can assume it's an int variable named myVariable and it is defined elsewhere in the program." Think of the compiler generating the code for the variable but instead of suppling the variable's lvalue, it leaves "????" in the generated code where the lvalue should be. Then, in the Arduino environment, in the INO file we find the definition of myVariable: ??? int myVariable; which is the program statement that defines the variable myVariable. This definition allocates storage and allows the compiler to fill in the lvalue for this variable in the symbol table. Now, after the compiler finishes, the linker comes along looking at the generated code from the compiler and sees the ???? marker in the object file, looks in the symbol table for ???? in the symbol table, and substitutes that variable's lvalue for the ???? marker. When it's done with that, the linker continues to stitch in the code from the libraries and any other extern declarations to generate the final program code. Using the terms define and declare as if they are the same concepts is wrong, but most programmers fail to make the distinction. Indeed, even Microsoft's documentation treats the two terms the same. Programming is confusing enough without confusing the terms that are integral to it. Jack, W8TEE ?
On Saturday, February 15, 2025 at 10:59:24 AM EST, jerry <jerry@...> wrote:
? I'm not a fan of this coding approach where class methods are defined > in a header file...I just don't like to see executable code in a > header file. Nor do I like the idea of each cpp file having it's own > header file. I just seems like clutter to me. On the other side, I > think this was written by Paul and I have the utmost respect for his > code. Kinda a rock/hard-place for me. > > Jack, W8TEE I OTOH like the idea of a matching header file for each .cpp file.? Having everything in SDT.h seems.... like clutter.? Lots of scanning up & down in that huge file.? How to find the prototypes to call stuff in CAT.cpp?? Easy, they're in CAT.h.? No scanning up & down. Aesthetically, that giant SDT.h file gives me a similar feeling to seeing a few zillion global variables. You and Al architected the T41 as a collection of small modules with well defined functions and interfaces that can be dropped in & out.? I feel that the software should be the same way.? A .cpp file/.h file pair with well defined interfaces that can be dropped in & out.? So - for example - if I want a CW keyer in another project, I can grab cw_keyer.cpp and cw_keyer.h, and I pretty much have it.? Yeah, I'll have to tweak them for another architecture, but I won't have to go scanning through some giant file to find the bits that correspond. I do agree on the concept of not having anything whatsoever executable inside an include file.? Or rather - not having anything that assigns storage. A class definition doesn't assign storage.? But it still looks messy. ? I did use the USB output on another project.? It worked fine.? It should work here too.? Time to get to work. ? ? ? ? ? ? ? ? - Jerry -- Jack, W8TEE |
|
Re: FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
It's different for every different amp design... needs to be tested, BUT IN GENERAL you want enough headroom so that you never reach saturation of the devices... that means PTP power divided by four.
toggle quoted message
Show quoted text
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: www.VillaGrandPiton.com Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. email: bill@... -----Original Message-----
From: jerry <jerry@...> Sent: Friday, February 14, 2025 9:09 PM To: [email protected] Cc: K9HZ <bill@...> Subject: Re: [AmateurRadioBuilders] FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress On 2025-02-14 16:16, K9HZ wrote: More mumbling about APP¡ operating the amp at less than 25% of its*** Does it have to be 1/4? How much improvement would 1/2 of available output give you? I recently saw a new LDMOS device that's rated for 2.5kW CW output. I think it runs off 75V. I was thinking that at 1.5kW output, it might be pretty clean. Or would IMD due to near flat-topping be replaced with IMD due to crossover distortion? - Jerry, KF6VB |
|
FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýMore mumbling about APP¡ operating the amp at less than 25% of its average available output gives better IMD.? DUH. ? ? 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 WA1MBA via groups.io
Sent: Friday, February 14, 2025 9:56 AM To: [email protected] Subject: Re: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? In my recent talks about IMD, through observations of many amplifiers, most of which were Class A units, I came to the conclusion that runnunig 6 dB below the P1dB compression point kept the 3rd order product below 30 dB. Often much lower. Just a rule of thumb. ? ?There is at least one mfgr of amplifiers that rates them at 3kW (max, whatever that means) and gives good IMD performance at 1kW. Many hams solid state amplifiers are run at or close to their P1dB point on voice peaks.? ? ?Care has to be taken at all stages of analog design because every amplifier and mixer throughout a transceiver produces IMD. I believe that most modern radios are pretty clean up to the final amplifier where cost often dictates non-linear choices. All that said, producing -50 dBc or better IMD products before the power amplification requires detailed engineering of analog circuits. This low level is easily obtained and exceeded in a good SDRs of 14 or 16 bits RF sampling. Most readers of this already know that SDRs are good radios for many reasons. Clean signals is one.? ? ?The low level (0 dBm) 3rd order IMD output from my 6700 at 28 MHz was below -80 dBc. I say below because my two tone audio source measured about that level of IMD.? ? On Fri, Feb 14, 2025, 10:22?AM Dave via <WB1S=[email protected]> wrote:
|
|
FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýWell this is a load of crap.?? It¡¯s a good way to cover the problems up¡ that¡¯s all.? Any RF engineer will tell you¡ stop it early in the design¡ not at the tailpipe. ? ? 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 WA1MBA via groups.io
Sent: Friday, February 14, 2025 8:16 AM To: [email protected] Subject: Re: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? Rob,? ? ?I understand your point, but as we know radios are different. I would compare a Flex 6xxx or 8xxx plus a Power Genius favorably against most other solid state radios and KW PAs. The Flex power amplifier ($6k on sale) is one of the cleanest solid state 1.5 KW class HF amplifiers. It isn't as "IMD clean" as a class A amplifier, but with it's dynamic bias control and harmonic diplexer it is pretty good. ? Both of these features are incorporated to achieve good efficiency while minimizing the causes of IMD. As you have clearly demonstrated here and in your talks, PD is the only way to achieve both very low IMD and high efficiency. And Adaptive PD is superior to static as it includes the changing operational variables (antenna load, and temperature effects) into the dynamic control loop. ?I operate on VHF and above, and successfully include the entire transverter and VHF PA in the APD loop with my Apache. There are very few low IMD high power stations on 2 meters and above. I'm eager (and prepared) to do the same with my 8600. |
|
FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýThere¡¯s that ¡°Class-A¡± thing again¡ ? ? 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 Rob Sherwood via groups.io
Sent: Thursday, February 13, 2025 9:56 PM To: [email protected] Subject: Re: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? There is nothing magic about a Flex, Icom or Apache transceiver or a KPA1500 or PG XL as they are all about the same without pre-distortion.? One rig that I have tested that passes the ARRL CSI SSB splatter mask is a Collins 32S-3 with a lot of negative feedback and 6146A tubes in the final.? One option for clean transmitters was Class A (3 discontinued Yaesu rigs) plus high quality tube linears.? Everything solid-state needs pre-distortion help, and hopefully eventually four of the six major OEMs will offer that feature.? I have heard nothing out of Kenwood and the FTdx-101MP dropped class A. ? With pre-distortion we can get back to what was available in the past.?? Note:? To convert dBc to dB PEP add 6 dB.? ? Rob, NC0B ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Bill VA3WTB via groups.io ? Rob, when I see a signal over S 9+ and the transmission is virtually clean I think that is good. Looks nothing like the examples your showing with a radio not adjusted correctly. I used to send screen shots of Dave W02X transmissions as his signal was 10 over. Yes it wasn't perfect,? it had just a little out side his band pass. So we are not saying APD Is not great. But everyone knows a Flex can look very clean when used correctly. Some radio's it doesn't matter what you do, they are horrible.? Bill ? ? ? ? |
|
FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýfyi ? ? 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 Rob Sherwood via groups.io
Sent: Thursday, February 13, 2025 7:25 PM To: [email protected] Subject: Re: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? Hi James, ? Certainly overdriven linear amps are a problem, but solid-state rigs and solid-state amps without pre-distortion are depressingly non-linear.?? Here in rebuttal is ?another slide from my CSI Flex presentation.? In this case the clean signal is an Apache 200D with a solid-state amp in the correction loop compared to my TS-890S and my Alpha 89 being carefully monitored with a Tektronix scope to assure no linear flat-topping.? My non-predistortion signal is virtually the same as the Flex 6600M and PG XL.? All Flex has to do is ship pre-distortion and it can look like the Apache PureSignal and Icom DPD examples.? ? ? Rob, NC0B From: [email protected] [mailto:[email protected]] On Behalf Of jjames700 via groups.io ? Rob, The image of the 6600M looks more like someone that is over driving the amplifier and causing splatter.? I think nearly all the splatter seen on the bands is caused by the operator more than anything else.?? James? WD5GWY? ? |
|
Re: RX-888
¿ªÔÆÌåÓýI¡¯m trying to get mine working and it appears the first step is to add the driver for the CYUSB chip to windows¡ but for some reason windows deactivates it and I can¡¯t get past that.? Do you know something different? ? ? ? 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 mk3msm via groups.io
Sent: Thursday, February 13, 2025 2:05 PM To: [email protected] Subject: Re: [AmateurRadioBuilders] RX-888 ? yes ! On 13/02/2025 19:52, K9HZ via groups.io wrote:
? |
|
RX-888
¿ªÔÆÌåÓýAnyone here have a RX-888 MK-II SDR working? ? ? 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@... ? ? |
|
Re: FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓýGary, I¡¯d like to see more here on this subject¡ ? ? 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 Gary via groups.io
Sent: Thursday, February 13, 2025 7:58 AM To: [email protected] Subject: Re: [AmateurRadioBuilders] FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? I am seeing results like this using a Radioberry driving your 20W amp. Gary W9TD |
|
FW: [FlexRadioSmartSDR] Adaptive Predistortion Progress
¿ªÔÆÌåÓý±õ²Ô³Ù±ð°ù±ð²õ³Ù¾±²Ô²µ¡ ? ? 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 K1VF1970 via groups.io
Sent: Wednesday, February 12, 2025 10:10 PM To: [email protected] Subject: Re: [FlexRadioSmartSDR] Adaptive Predistortion Progress ? As a followup to an abbreviated post last month, attached is a more complete summary of recent IMD measurements of adaptive pre-distortion capabilities on a traditional vacuum tube and a more modern LDMOS Linear Amplifier.? With the recent announcements by Flex of a long anticipated and highly requested feature, these results demonstrate what's possible, and certainly set the bar for IMD performance. ? Vince, K1VF? |
|
Re: For you designer builders...
¿ªÔÆÌåÓýAnd these are not the kind of parts that even the most skilled builder would want to solder onto a board.?? If I ever do this, the boards will come pre-populated.? They are 3mm x 3mm.? YIKES! ? ? 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 Jack, W8TEE via groups.io
Sent: Wednesday, February 12, 2025 11:47 AM To: [email protected] Subject: Re: [AmateurRadioBuilders] For you designer builders... ? They seem to have a large price drop (~25%) when you go from 1 to 10 units...almost in half when you buy 25 units. Maybe pre-orders would help you cut costs. ? Jack, W8TEE ? On Wednesday, February 12, 2025 at 12:35:25 PM EST, K9HZ <bill@...> wrote: ? ? ARG!!!? LT3042 and LT3045¡ ? ? 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 K9HZ ? I attended an online seminar/ instruction/ discussions today (with a friend of mine) regarding power supply devices and I learned a lot.? First off 7805 voltage regulators are very noisy¡ in fact generate 40nV of noise at best.? That noise gets into the A/D and D/A so with a 24 bit A/D with resolution of 298 nV (on 5V¡ its worse on 3V being 179nv)m that 40nV gives you a much higher noise floor and less dynamic range.? Buck/boost regulators are far worse.? There are ultra-low noise regulators that should be used with projects that use high resolution A/D and D/A converters in radios¡ like the LT3042 and LT3042 that are about 80db below a linear regular in noise generation.?? They are about 10x more expensive than the 7805 series regulators, but are critical to low noise floors. ? As a result, when I get time (and that may be years from now)¡ I¡¯ll make some measurements on the T41 hardware for absolute noise floor and then sub in these low noise regulators and see what I measure. [nb. my thought would be to make small vertical boards with these low noise regulators on them¡ which are flat packs¡ to simply replace the 7805 type regulator with heatsink]. ? Lots to do. ? ? 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@... ? ?
|
K9HZ
Jack, W8TEE
Gary