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Author Topic: QS1R Feedback  (Read 27906 times)
ZENKI
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Posts: 956




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« Reply #15 on: October 03, 2011, 12:51:39 AM »

I wont hold my breath expecting that any ham SDR transmitter manufacturer will produce a transmitter with a clean PA. They all seem  have great ideas  and unfortunately when it comes to delivering a PA stage they  produce a 12 volt bipolar amp with IMD  specs that are no better than the worst CB radios.

Even the famed HPSDR groups produces a nice transmitter like the Penelope that is clean as can be, then they sell a 12 volt bipolar kit that cant maintain the drivers excellent IMD performance.  Its unfortunate that by the time most manufacturers finish designing a transmitter they seem to run out of energy and creativity and dump in any old 12 volt CB PA design with the worst possible IMD performance.  Look at  all the current high performance radios, K3, orion, Eagle and any other brand, they all have poor TX IMD performance.

I would have thought that era of SDR  transmitters would usher in a new age of high performance transmitters, unfortunately all we getting is the same old crap. I will bet that the QST1 and the new RFSPACE transmitter will have the usual poor TX   IMD performance.





As stated it's an exciter which has been announced, i.e. not available yet. Now you can speculate why not a transmitter. Obviously he ran into problems generating clean signals. It is much easier to produce and filter small signals.
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KA4POL
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Posts: 2028




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« Reply #16 on: October 03, 2011, 03:12:29 AM »

I'm afraid you are right. Cheap Mosfets like IRF510 are no good for clean signals.
But this is the fault of those who think a good amplifier must be as cheap as possible.
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N9VV
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Posts: 14




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« Reply #17 on: October 03, 2011, 06:36:10 PM »

On 10/3/2011 6:46 PM, ke5jpp wrote:
>
> As stated it's an exciter which has been announced, i.e. not available yet.
> Now you can speculate why not a transmitter. Obviously he ran into problems
> generating clean signals. It is much easier to produce and filter small signals.
>


I think this fellow has reached a totally bogus conclusion
about the QS1E.

[1] Phil held a Poll of the 1800+ Yahoo Group Members asking what power
level they wanted. The Poll results are there for analysis by anyone,
but even a casual observer sees that there was an almost even split
between the 100mw and below group and the 5W and above group <g>

[2] Phil had to decide what size board and thermal issues made the most
sense to add this QS1E to existing QS1R Receivers. He promised the
original buyers/customers that he would follow with a modular approach
that would allow you to expand your QS1R using it's present Hammond case.

[3] His QS1E meets requirement #2 *and* allows for the addition of the
RFFE1 bandpass/preselector inside the QS1R case with no new ventillation holes or fans needed! He will supply a new end panel to accommodate the necessary connectors. The QS1E and RFFE1 connect to the QS1R via the EXISTING sockets that Phil engineered into the design back in 2007.

[4] The output of the QS1E is as clean as Phil can make it. He is a real Ham and wants his signals to be Class-A or better with no birdies and no spurs and no Tx IMD issues. It will be fun to see the published
performance numbers for the new QS1E.  The inductors used in the QS1E
and RFFE1 will probably surprise many designers. I sure look forward to
seeing what SMT units are used.

[5] Phil has stated that due to the thermal issues of creating a clean
10W unit, he will design an external companion Linear Amplifier PA to go with the QS1E. The end-user is left with an extremely clean and reliable Tx IMD signal to amplify as they wish.

[6] The fellow who was quoted, must not have investigated the four
DDC/DUC units that are being developed; (a) QuickSilver, (b) SDR-ONE by
RFSpace, (c) N2ADR/DB1CC "HiQSDR", and (d) the "Hermes" from the
OpenHPSDR group. *NONE* of these designers has ever mentioned a problem
generating a clean signal!  As a matter of fact, the Tx images provided
by these Engineers show EXCEPTIONALLY clean Tx output. Links to all four projects are on my webpage: http://www.n9vv.com

[7] Dr. Doug Smith PhD KF6DX, who wrote the ARRL DSP book, said emphatically in three QEX articles that the Sherwood testing methods are for ANALOG RADIO's and do not apply to the Third Generation DDC/DUC equipment that the QuickSilver Project is creating. Entirely new testing methods are needed. IP3 is quite a joke among SDR Engineers. I suggest you watch the VK6APH presentation at the 2009 ARRL DDC Conference where he discusses the DDC in detail and why none of the tired old Analog measurements apply.

[8] The QS1E should be released in October if the manufacturer of the boards can meet Phil's rigid requirements for quality. The RFFE1 has been designed and tested in prototype and should be released later this year. The Linear Amp PA to go with the QS1E will also be tested in prototype and finished by as soon as possible.

[9]  It has taken Phil six years to reach this milestone. He is a SINGLE PERSON company and has to do all the design/engineering/testing/production/webpages/software/firmware/shipping and service all by himself. I would say his record is quite astonishing with a total rewrite of both the Server and Client software in the past 6 months.  His QS1R DDC board has been stolen and cloned in England, Germany, Amsterdam, The Ukraine, and China. He no longer releases the design details of his equipment to try and protect his Intellectual Property and recover some of his personal savings that has gone into creating the QuickSilver phenomenon.


thanks for allowing me to express my opinion,
73 de Ken N9VV

« Last Edit: October 03, 2011, 07:03:16 PM by N9VV » Logged
KA4POL
Member

Posts: 2028




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« Reply #18 on: October 04, 2011, 02:15:41 AM »


... bogus conclusion


[1] Phil held a Poll of the 1800+ Yahoo Group Members asking what power
level they wanted. The Poll results are there for analysis by anyone,
but even a casual observer sees that there was an almost even split
between the 100mw and below group and the 5W and above group <g>
Talking about bogus conclusion, at this time the result of the poll is:
                             votes     %
1 mW ( 0 dBm )            9    12    
10 mW ( 10 dBm )        4       5    
100 mW ( 20 dBm )    11     15    
1 W ( 30 dBm )            13    17    
5 W ( 37 dBm )            36    49

So just 73 have voted as a matter of fact.
100mW and below: 24
1W:                      13
5W:                      36

Any more questions  Grin
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N8VB
Member

Posts: 21


WWW

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« Reply #19 on: October 04, 2011, 06:34:12 AM »


Talking about bogus conclusion, at this time the result of the poll is:
                             votes     %
1 mW ( 0 dBm )            9    12    
10 mW ( 10 dBm )        4       5    
100 mW ( 20 dBm )    11     15    
1 W ( 30 dBm )            13    17    
5 W ( 37 dBm )            36    49

So just 73 have voted as a matter of fact.
100mW and below: 24
1W:                      13
5W:                      36

Any more questions  Grin

Hello Dieter,

Anyone who thinks that I based the design of the QS1E on a simple poll of output power is quite naive.   Wink

I had many responses from QS1R users via email and in the QS1R group concerning not only power output, but the desire for cleanliness.  It is very clear that different users have different expectations for what "a clean output" means.  I wanted to offer a low cost solution for existing QS1R users that would allow for the greatest versatility in use.  The QS1E will not only allow the QS1R to have transmit capabilities - it also will allow the QS1R to be used as a piece of test equipment with the QS1E acting as a signal/tracking generator.  

Your conclusion that I had some kind of difficulty in designing a clean power amplifier is incorrect.  I do have such a design and it will be offered as an add-on for those who want a very clean amplifier.  The QS1E will allow us to experiment with adaptive pre-distortion.  By not forcing users into using a particular RF PA, users can pick the power level and "cleanliness" they are happy with.  Some users want to use the QS1E with their transverters which only require -10 dBm input.  The QS1E itself provides an extremely clean adjustable RF output from -10 dBm to +10 dBm.  

Phil N8VB

« Last Edit: October 04, 2011, 06:37:02 AM by N8VB » Logged
N8VB
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Posts: 21


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« Reply #20 on: October 04, 2011, 06:45:45 AM »

I will bet that the QST1 and the new RFSPACE transmitter will have the usual poor TX   IMD performance.


Hello "Zenki",

The QS1E offers exceptional TX IMD performance.  Even with the add-on companion PA.  The QS1E will also allow us to do adaptive pre-distortion.

It is expensive to design and build an exceptionally clean RF PA.  Many of the same guys who complain about TX IMD performance would complain about the high cost of a transceiver with such exceptional TX performance.  That is one of the reasons that manufacturers provide transceivers with "good enough" TX IMD performance - which in some cases is horrible.

Phil N8VB

« Last Edit: October 04, 2011, 12:14:49 PM by N8VB » Logged
WA2ELZ
Member

Posts: 15




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« Reply #21 on: October 04, 2011, 05:33:06 PM »

As stated it's an exciter which has been announced, i.e. not available yet. Now you can speculate why not a transmitter. Obviously he ran into problems generating clean signals. It is much easier to produce and filter small signals.

Hello Dieter,

I am very happy with Phil's plan to provide an exciter. An exciter is far more valuable for my needs than a transmitter. A transmitter is also good, but doesn't a transmitter design begin with a well designed exciter? This will give me a justified rational to design my own power amplifier if I choose. I do not feel that the exciter design is a fall back position due to "problems generating clean signals". I love my QS1R, and can't wait for the excitement to come.
« Last Edit: October 05, 2011, 07:30:42 AM by WA2ELZ » Logged
ZENKI
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Posts: 956




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« Reply #22 on: October 06, 2011, 01:52:44 AM »

Hi Phil

Great to read that QST1 will have a clean transmitter. This will be good starting point towards a  linear QRO PA. I dont know what the target retail price will be for the QST1, whatever it is I would be willing to pay double for the option of having the adaptive feedforward/ultra clean PA. I am assuming here that the QST1 will cost lest than say a FT5000 or Icom 7700! So I do believe that  doubling whatever your final price will be,  will be good price to pay for building a ultra linear TX platform which many hams are seeking. I think you will be surprised at how many hams would be willing to pay for this as a option.


Anyway good luck with the QST1, I look forward to buying one when its released, I also look forward to the ongoing developments for things like adaptive pre-distortion whenever it  is developed.



I will bet that the QST1 and the new RFSPACE transmitter will have the usual poor TX   IMD performance.


Hello "Zenki",

The QS1E offers exceptional TX IMD performance.  Even with the add-on companion PA.  The QS1E will also allow us to do adaptive pre-distortion.

It is expensive to design and build an exceptionally clean RF PA.  Many of the same guys who complain about TX IMD performance would complain about the high cost of a transceiver with such exceptional TX performance.  That is one of the reasons that manufacturers provide transceivers with "good enough" TX IMD performance - which in some cases is horrible.

Phil N8VB


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WB6RQN
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Posts: 484




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« Reply #23 on: October 18, 2011, 04:58:38 PM »

30dB gain blocks with output levels approaching +30dBm are available from MiniCircuits for not a lot of money. Virgil Stamps is working on a new HF SuperPacker Pro V3 amp that can be driven from a +20dBm (100mW) signal. It wouldn't take much to turn the exciter into a transmitter.

And as for talking about direct-sampling receivers, has anyone thought about how ADC noise figure impacts dynamic range?

73 de Brian, WB6RQN/J79BPL

P.S. In case anyone has been wondering where I have been, I've been really busy. I just finished building a car. (And it runs great! We thrashed it at Thunderhill and it didn't complain a bit!) FWIW, if anyone is looking for an argument over the pros and cons of Flex Radio Systems, they need to look somewhere else as I am not interested.
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M0HCN
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Posts: 473




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« Reply #24 on: November 01, 2011, 01:41:35 PM »

On the clean PA/exciter thing, I have a prototype all HF band transmitter on the bench downstairs that a 2 tone IMD3 of -63dB ref one tone (-69 ref PEP) @ 250W, via cartesian envelope feedback. It still needs the output filter board designing and building, but that is just a case of winding 20 or so large toroids.

The driver and PA stages are actually very conventional for the most part, RD16/BLW50F/BLW96 pairs, held to about 10db per stage with local feedback, with the overall envelope feedback error amplifier pair having 40db of gain, which, when you close the loop, makes the distortion just vanish.
Holding the stage gains down with local feedback means I need about 2 more gain stages then I would if I ran the things wide open, but  means that even open loop the performance is very much better then a lot of current commercial offerings.

The complexity is adding a couple of extra DDS chips, some ultra low noise opamps and a few more mixers, but I think it is worth it. 

My current project is to improve the efficiency of the PA by playing games with the supply voltage and bias using feed forward control from the DSP that produces the modulation signals. If I can get the average transmit power efficiency up far enough then the savings in heatsink metal may pay for the cartesian loop electronics.

One day I might write it up for Radcom/QEX/Dubus or just possibly just for the web.

Regards, Dan.
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SWL535
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Posts: 10




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« Reply #25 on: November 15, 2012, 08:22:21 PM »

Coming up on 1 year after the RFFE1 Wiki update.....not a word....when you ask there are no replies...dead silence.

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White Rock, BC Canada
ZENKI
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Posts: 956




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« Reply #26 on: November 16, 2012, 01:28:14 AM »

QSR1 and QST1 is like the the ADAT radio, a dead end road going nowhere fast. Its unfortunate but I suppose when its not your full time job and a hobby you cant expect much.

I have a QSR1  and I like it a lot, its a wasted investment now since I just got my Hermes radio. I would suggest  you look at this option.

My Hermes with a Class A 10 watt amp is superb. I just putting the finnishing touches to my VRF150 amp with diplexer filters. I really dont need any other radios at the moment. Well I do, A HPSDR Hermes with a front panel!

HPSDR Hermes is a superb solution  and it is very affordable and blows away anything on the market at moment.

Coming up on 1 year after the RFFE1 Wiki update.....not a word....when you ask there are no replies...dead silence.


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KE5JPP
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« Reply #27 on: November 16, 2012, 03:32:28 AM »

Coming up on 1 year after the RFFE1 Wiki update.....not a word....when you ask there are no replies...dead silence.

That is because users have found that they don't need it.  They are using filters and pre-amps from Clifton Labs, DX Engineering, and Minicircuits.  This information is on the Wiki if you bother to look for it.  I use a Clifton Labs norton preamp above 20 MHz with mine.   Then there is the appliance operators who think that unless their noise level is S9+20 on 80 meters, they don't have enough gain and they go looking for a pre-amp.   Roll Eyes  They are the same ones who chase columns of meaningless numbers on the Sherwood list.  There is no hope for those guys.

Gene
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KE5JPP
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« Reply #28 on: November 16, 2012, 05:11:14 AM »

QSR1 and QST1 is like the the ADAT radio, a dead end road going nowhere fast. Its unfortunate but I suppose when its not your full time job and a hobby you cant expect much.

I have a QSR1  and I like it a lot, its a wasted investment now since I just got my Hermes radio. I would suggest  you look at this option.

My Hermes with a Class A 10 watt amp is superb. I just putting the finnishing touches to my VRF150 amp with diplexer filters. I really dont need any other radios at the moment. Well I do, A HPSDR Hermes with a front panel!

HPSDR Hermes is a superb solution  and it is very affordable and blows away anything on the market at moment.

Coming up on 1 year after the RFFE1 Wiki update.....not a word....when you ask there are no replies...dead silence.


Weren't you just singing the praises of the ADAT a few weeks ago?  Now you are trashing it.  You already have very little credibility because you hide behind fake names like 'zenki' and 'plebian99' and your credibility further suffers when you continually post conflicting information.  Of course, being an anonymous coward, you do not worry about the embarrassment of continually contradicting yourself, do you?   Roll Eyes

I bought into the HPSDR stuff early on and it ended up being a huge sinkhole of wasted money and time.  It is supported by 'volunteers' and the software is in a terrible state.  Trying to figure out what version of firmware or software to load brings you multiple conflicting advice from the 'volunteers' on the mailing list.  When you eventually find and use the esoteric firmware loading program, you next find out that the firmware they told you to load is not the correct version for use with the current software available!  The only half way usable software for the HERPES, err... HERMES is based on a kluged version of Flex Radio's PowerSDR which has been stripped of Flex's latest 'features' such as the tracking notch filter.  PowerSDR also limits you to sound card sample rates of 192 kHz max, when the HERMES can do more.  The other 'volunteer' developed software is not usable and does not support transmitting and is continually deficient in any useful features.  They are more worried about trying to listen to 7 receivers at once then how you are going to transmit with the thing.  NO THANKS!

The ADAT is available and can be purchased, so I'd say it isn't dead.  It is too expensive, in my opinion, but still cheaper than the Flex-6000 series.   As far as the QS1R, there is no QS1T, so you obviously are talking out your you-know-what once again.  It is called the QS1E, not QS1T.   I have been using the QS1R with the QS1E exciter add-on board with my external class A amp for six months now.  The QS1E came out 6 months before HERMES.  At least the QS1R software is supported by a company with active development and not a lot of fooling around you have to subject yourself with the unsupported HPSDR stuff.

Gene
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SWL535
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« Reply #29 on: November 16, 2012, 06:38:13 AM »

This information is on the Wiki if you bother to look for it.
I did "bother to look for it" but I would prefer the pre-amp/filter board to be....
A-be mounted in the QS1R box
B-be made FOR the QS1R by the same designer.

Did you "bother to look" and see I'm an SWL not a Ham....why would I want a Hermes?!
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White Rock, BC Canada
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