RXTX Ensemble Build(s) project.

#88190

Hello Guy,

Nice to hear about your project. Sounds like this will keep you occupied for a while an provide lots of enjoyment.

Your plan to build the first RXTX as designed sounds prudent. 

If you choose to build the 2nd unit for the 160-10m design, that should be quite straightforward for you after having done the first unit. Building the modified design, starting from a bare board, would involve very little more work than does the standard design.

I use my RXTX on CW. The latency is manageable, although not the experience of a conventional full break-in rig.

If you have any questions, problems, or suggestions for improvements, please let me know.

Roger

Show quoted text

On Sep 23, 2020, at 9:54 AM, Guy Mengel <guy@...> wrote:

All,
I have not seen much recent building on this site so I will start posting about the build(s) I am doing.  I built a softrock-40 many moons (years) ago and then gave it to someone.
I am interested in SDR's but dont have the $ to throw 3-10K into a QRO rig.  So, I spent (89x3 + $65) on 3 RXTX units, and one Ensemble II receiver.  I was (am) inspired by Roger's postings, and Brent Dewitt's Rig(s) [Dual RXTX in a single box].   I have started the build, and have the first RXTX communicating with the Computer and the SI570 generating squarewaves.   I am working on this as I have time. This Covid 19 Virus and the University I work at has my time all bollixed up.  Here are my ideas.
1. Build first RXTX unit and make sure it works as designed (80/40?) or ?
2. Build second unit, but broadbanded per Rogers multi-band rig.
3. Build third unit... as ?
4. The Receiver is for experimentation.

Much more fun than simply stuffing boards.. 
I am also building from scratch a tayloe modular unit like what you see on  including the tube amp..  Not very far along on this.. still putting schematics in the computer.

I am a CW guy but @ about 25wpm.. latency issues may creep up on me with SDR we will see.

I am interested also in modeling the filters that will be necessary with a VNWA3EC I have.  Along with a hacked specan using a RSPDUO with spectrum analyzer software.

Anyway.. hope to post a bunch and have fun.    Prelim pics here: (not much there yet!) 

73 Guy N1GMM. hope all are well! 

#88191

Roger. Thank you for the encouragement. 
Just finished the 40/30/20 build. All went well. 950mw out first check. 
Pictures are here. Mostly old hat for most here. 
Next. The broadband rig. And then....thinking seriously about top band and below. After reading your materials.
..
Thanks again for the encouragement.  This kit is definitely not for the beginner. Indeed. 
I love the transformers. I love the fiddly stuff. 




73 
Guy N1gmm

#88192

Guy,

Congratulations on completing the build and quick success! Nice work.

Re. the broadband version, someone who recently built one told me that he had used the supplied small transformer cores and fine wire and they worked fine on all bands. I had substituted larger cores and wire to make the winding easier for me. So if you love winding transformers, you get to have more fun with the next one. As for the order of build and testing, you can follow the same procedure as for your first one (rather than the procedure I suggested for modifying an existing standard build), just substituting the new parts as you go along.

73,
Roger

Show quoted text

On Sep 27, 2020, at 3:37 PM, Guy Mengel <guy@...> wrote:

Roger. Thank you for the encouragement. 
Just finished the 40/30/20 build. All went well. 950mw out first check. 
Pictures are here. Mostly old hat for most here. 
Next. The broadband rig. And then....thinking seriously about top band and below. After reading your materials.
..
Thanks again for the encouragement.  This kit is definitely not for the beginner. Indeed. 
I love the transformers. I love the fiddly stuff. 




73 
Guy N1gmm

#88193

Hi Roger;
I have your document before me and I am putting together a BOM for the build of the 160-10 Meter Mods.
In your document you state: " iii)	replace the old filter with a set of switched or plug-in filters that will cover all bands. Andy, YL2QN, has designed and built a switched filter for his RXTX mod. "


For the External Filters
I have looked everywhere in the forum (its huge) for YL2QN's switched filter.  I would love to see what he built. (these (BP?)filters between the QSE mixer and driver...  Do you have a link?

I have your switched filter as well (the link to the 3 pole 6 Position Switch has expired) It actually pointed to a 1 pole 6 pos, 3 stack switch.. This is actually the external LPF.  These switches are pricey. Unless I wait for the slow boat from China... 

I read your Rationale as well about the filters...it is the QSE BP filter that has me a bit confused.. Do you have a design with different plug in filters?

I am enjoying this greatly.  Thank you again Roger..

PS.. I wonder why the 6.3 design with the plug in filters was discontinued by Tony.. perhaps I have not read enough..
PSS. Thanks for the patience for a VERY latecomer to use these Softrocks.. 

Guy

#88207

Guy,

Re.
I read your Rationale as well about the filters...it is the QSE BP filter that has me a bit confused.. Do you have a design with different plug in filters?I see that my write-up is not clear on this. It is necessary to remove the standard bandpass filter that follows the TX mixer (which restricts operation to e.g. 80-40m) so that the RXTX will work on all bands. If this BP filter is simply replaced with a jumper then that will work. However, the level of the IMD spurs is higher than desirable (and at least on some bands higher than the FCC specified limit of -43 dB down from the main signal). See the Note 1 measurements. I am recommending that low pass filters be installed after the TX mixer, which requires that there would be several of them so some means of plugging them in or switching among them would be needed.
I provided the values for two filters, a 30 MHz one that would work for 20m thru 10m (see Note 1), and a 14.3 MHz one that works for 40m thru 20m. Values were not provided for lower bands. If you are only going to run 1 W output from the RXTX, or to a low power amp, maybe 20W, the IMD spurs will be so low as likely never to cause problems. If you plan on running 100W plus, then I would strongly encourage having low pass filters on the TX mixer output.

I have a set of 6 low pass filter that are relay switched in. That many would not be needed, I happened to have access to a board with the necessary circuitry.

Does this help Guy?

Roger

On Sep 29, 2020, at 7:10 AM, Guy Mengel <guy@...> wrote:

Hi Roger;
I have your document before me and I am putting together a BOM for the build of the 160-10 Meter Mods.
In your document you state: " iii)	replace the old filter with a set of switched or plug-in filters that will cover all bands. Andy, YL2QN, has designed and built a switched filter for his RXTX mod. "


For the External Filters
I have looked everywhere in the forum (its huge) for YL2QN's switched filter.  I would love to see what he built. (these (BP?)filters between the QSE mixer and driver...  Do you have a link?

I have your switched filter as well (the link to the 3 pole 6 Position Switch has expired) It actually pointed to a 1 pole 6 pos, 3 stack switch.. This is actually the external LPF.  These switches are pricey. Unless I wait for the slow boat from China... 

I read your Rationale as well about the filters...it is the QSE BP filter that has me a bit confused.. Do you have a design with different plug in filters?

I am enjoying this greatly.  Thank you again Roger..

PS.. I wonder why the 6.3 design with the plug in filters was discontinued by Tony.. perhaps I have not read enough..
PSS. Thanks for the patience for a VERY latecomer to use these Softrocks.. 

Guy

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RXTX Ensemble Build(s) project.