New Sherwood 6700 and 6300 tests

James Del Principe

HEY!! I had an Eico 753 and it was a lot of fun.... I currently use a DX100 B and HQ 170 for rag chewing on 'antique modulation' every morning on 75M. ....but just for old times sake.

Mike va3mw

I'll trade with you. I just need to find it but you'll have to fix the drifting.

James Del Principe

I understand what they are saying but I am not referring to a condition where the antenna is connected but not tuned to a signal. Of course, in that condition there would be an 'S' meter reading due to atmospherics and extranious noise from who knows what.
What I am referring to is with the antenna shorted out at the radio.  There is (hopefully) no input to the Flex at that time but I still get a reading of about S3 to S4.   

Gopro

You have said that

Gopro

Yes, phase noise is extremely important -
 that's the reason why Collins 51S1(146dBc/Hz at 10kHz)
outperforms almost any modern radio - just endless quietness.

Gopro

The real reason why  Flex, with antenna input shorted, shows S2-3 lies in Flex
noise floor. It is only -118dBm or 0,282uV  and that is roughly S1.
Your S meter reads even more (what means your Flex have even higher noise floor -
or otherwise, is more deaf).  Maybe you have AGC out of order or is something wrong with rig?
But don't worry, noise floor of your antenna is certainly between -115 to -110 dBm
(0,398 to 0,707 uV) so far above Flex's 0,282uV.
Hope that helps.

KY6LA_Howard

@James

You are still missing the point... the Flex is a Laboratory Instrument giving an accurate measure of the noise at the antenna..  

BY OFFICAL DEFINITION S0= -127dBm and S9= -73dBM

On your legacy radios the S-Meter gives you a TOTALLY MEANINGLESS NUMBER which has no relevance to the actual signal but rather it gives an arbitrary number depending on how you Zeroed it out with a **** and relative to the APPROXIMATE signal strength received.   So S0 could mean -127dBm or -73dBm... It really is meaningless...

Albeit it seems to be aesthetically pleasing to some to think their radio is hearing S0.even when that really is say -73dBm...

Walt

James,

measured noise is also a factor of bandwidth.

Try this - go to 20 meters with your shorted antenna connector selected for the receiver (blue color indicator) , place the mode in USB and note the S meter reading - you can hover your mouse on the S meter to see an actual dbm reading.

Now - switch to CW and go to 50 cycle filter and record the S meter reading.  I think you will find it quite low - down near -132 dbm on mine and thats with an open antenna connector (I just switched the receiver to ANT 2 - which is open)

So, if you get the bandwidth down, you see less noise. 

I will let others discuss the bandwidth / noise equations . .

Hope that helps a little . . .

Cheers !

Ria

I get that icom scores better on the SherwEng tests. However the radio's internals have some shortcomings in the signal chain, plus I see hardwired knobs and no I/Q out as a disadvantage (many people run a computer in their shack anyway). Performance was a secondary concern for me. The first was multiple receivers, integration with skimmer and remote capability.  Truth be told, the differences in the top rigs are small, and any rig above 80 narrow spaced DR is going to work for everyone with human ears and ability. 

Alex_KM5YT

On hearing all this talking-down of receivers' sensitivity, I will note that on acquiring my first synthesized rig - an IC-751, I noted it didn't have a tunable front end, and filed that away, but also noted an absence of stations on 20M on too many evenings to
ignore - and bought a (Ameco I think) preamplifier.  Connecting and firing up this, I heard a lot of stations. Fast-forwarding to current era, I have a Heros preamp -
and after reading much of the above discussion, you'd wonder what keeps them in business!

Alex

Steve W6SDM

And to think that I started out with a Hallicrafters S38b. I wonder how that would fare in the Sherwood test?

Lee - N2LEE

I don't care what Sherwoods test show, there is NO Way the 7300 is a better radio than the Flex 6300. I have both and in the real world the 6300 is a much better performing radio.

The front end on the 7300 is overloads much more than the 6300 ever has.

Ria

On my 6700 on a dummy load on every band I get slightly less than S1 of noise. 
 

Rick WN2C

I have a 7drifty 3 going cheap!

Ross - K9COX

Back in the late 60's and 70's as a young man I used to repair CB radios to supplement **** money. On every radio I worked on would change the screen dropping resistor or the cathode bias for a few more watts out and adjust the S meter for a higher reading. They thought I was a miracle worker.

Jd Dupuy

Sherwood Tests = Who Cares!

James Del Principe

Well, I looked for the screen dropping resistor on my 6500 but was having a hard time finding it....   Do they use a dog **** resistor?   (a. I wuz just kidding and b. does anyone still know what a dog **** resistor is?)     Jim

James Del Principe

Ria, that would make sense. I did try changing the pass band with the antenna shorted and it did affect the 'S' meter level which does NOT make sense unless the noise is generated in the 'front end', prior to any pass band filtering.  

Gary

Rob loves the - or has stated he prefers the TS990 overall .... and I'd HIGHLY agree - don't question his integrity. He tested it for what he considered to be a valid reason in keeping with his mission. If its not important to you that is fine - but don't question his motives.

DH2ID

I was on the point of writing my opinion, when you took the words right
out of my keyboard - so to say ;-)
Thanks, Howard!

Duane N9DG

It is displaying the noise level (power for the IF bandwidth) of the ADC itself, and without any pre-amplification ahead of it. The ADC’s used in the Anan’s and IC-7300 have “native” levels in that same region. The difference is that those designs have stage(s) of gain ahead of the ADC all of the time. And then they add attenuation and/or vary the level of gain ahead of the ADC. In the 6K’s the “default” configuration is to feed the antenna input directly to the ADC. But they do offer the ability to add pre-amplification to get to the mid -130’s dBm minimum discernible signal levels like every other radio can achieve.

The 6K’s like virtually all PC-based SDRs back to the SDR-1000 are reporting the signal power in the IF bandwidth in absolute terms. Traditional radios in the past were most often reporting the analog AGC voltage level or now more likely in the DSP IF designs, the software AGC values. There is nothing absolute about their S meter values whatsoever. And as was said before, they lie.

Re the AGC-T setting: Based on your description I think you will have better luck starting with the AGC-T fully to the left and then advance the AGC-T slider to the right until there is a distinctly perceptible rise in natural band background noise. But no more. Backing off from the AGC-T from the full right until there there is a slight decrease in band noise is a long way from the optimal position of where the AGC-T being set to the boundary of the natural band noise. In the no signal present case you want to just distinctly be able to hear the natural background noise of the band. Advancing the AGC-T further right than that simply brings up the level of the band noise in the speakers. If you want more desired signal audio advance the AF gain. This AGC-T behavior is actually very similar to all analog radio RF gain controls of years past.

Varistor

Elecraft is very unlikely to be seeing decline in sales because of Flex. If anything, because of the wildly successful Icom 7300 and the upcoming in July 7610.

Duane N9DG

Also you must read the footnotes on Sherwood's table. While the table ranking order is sorted by 2 kHz RMDR. The numbers in that column don't necessarily reflect the way that you would normally run the radio. For example the IC-7300's RMDR entries and their associated footnotes:

94ab
81ac

ab     Measured with IP+ ON.
ac     Measured with IP+ OFF
NOTE: With IP+ OFF, intermodulation degrades gracefully. Recommend only using IP+ when absolutely necessary due to noise floor degradation.

Lawrence Gray

Agreed.  I bought a 7300 out of curiosity.  It is a great radio for the price.   However, it is in no way comparable to my 6500 in any real operating scenario.  After trying the 7300, I sold it.

Ranking receivers by an operationally irrelevant specification is basically dumb.  They should be ranked by the value(s) of specifications that actually matter in real use.

Larry, W1IZZ

SteveJ

You would care if Flex topped the Sherwood chart.

KS4JU

Well, here is my 2 cents on the topic. I personally really don’t pay a whole lot of attention to the numbers in the Sherwood tests because in my opinion they really don’t paint an accurate picture of the performance of any radio in “real world use” They don’t take into account price vs performance, build quality, features, or ergonomics. These are qualities that might make all the difference in getting a great radio versus a radio that has great performance but lacking in features or flexibility. I suspect that the average amateur radio operator would not be able to tell a whole lot of difference between most of the radios on the list unless it had a very severe short coming. The unfortunate side effect of all this is that some hams use these numbers to justify their purchases and wind up investing far more than necessary in a radio that doesn’t fully meet their needs. All too often these numbers are also used as “bragging rights” to imply that one radio is much better than another. Again not necessarily true in “real world” use.

In my opinion the testing methodology of software driven SDR radios is inherently flawed therefore rendering the testing from Sherwood not totally accurate. In my view the problem is that with SDR radios from Flex and Apache labs are always changing with updates to firmware and the client software. For example at some point Apache Labs will move to the Thetis firmware. This will probably wind up changing the performance numbers for the Anan series for better or worse. The potential for performance change is there with every firmware or client software update for Flex or Apache Labs hardware. You never see this information in the Sherwood tests as to what firmware or software version is tested. You also never see what end user settings are being used either. So frankly any performance numbers are not very useful for comparing SDR radios unless they are rerun after every major software upgrade. It would also be useful to know what the serial number of the radio tested was since the Flex and Apache Labs may have slightly different hardware tweaks from one manufacturing run to the other.

However the SDR radios from Icom like the 7300 and the new 7610 can be tested much like non SDR radios, because the are what they are. In other words the Icoms share more DNA with non SDR radios than Flex or Apache Labs SDRs in that the Icoms won’t change much over time. The 7300 and 7610 probably won’t have firmware upgrades that affect the performance of the radio that much. So far most of the firmware upgrades for the 7300 has dealt mainly with user interface issues and other small problems.

Is the Icom 7300 really better than the Flex 6300? Having owned both, I can say it depends on how you look at it. If you are looking at purely price the Icom 7300 wins. If you look at features though the 7300 falls way short versus the 6300. My personal experience between the two is that I feel that the 6300 is the better receiver of the two. The weak signal handling and noise floor seem to be much better on the 6300. I used the 7300 for a little less than a year. I finally sold it when I realized that it was mainly gathering dust because I always went back to using what I called my “real SDR radio”. Plus honestly, it was kind of boring.

I am not disparaging the 7300 in anyway and it’s a great radio for amateurs who want a self contained SDR radio. You have to give Icom credit for opening the door for SDR to become a more mainstream technology used in amateur radio equipment. However, I do have a big problem with Icom’s implementation of SDR or what I call “SDR Lite”. The one big fail for me on the 7300 was not allowing for IQ audio output. If they did you, could at least use HDSDR and Omni Rig to implement computer control and a large screen spectrum / waterfall display. That one little thing could have made a huge difference in the flexibility of use of the 7300 as well as the ability to leverage the the more advanced features available through SDR client software. The built in 4 inch touch screen is too small to be terribly useful. The inclusion of IQ output would have resolved that matter also. To be fair Icom did modify their RS-BA1 software to work with the 7300 to provide for remote use and waterfall / spectrum display on a remote PC. Another big fail especially when compared to the Flex system. First of all the RS-BA1 software is ancient and has never been modernized. The windows in the software can only be resized slightly, so no full screen spectrum / waterfall screen. Not to mention since the data can only transferred at 115,200 baud the waterfall / spectrum display was terribly slow and laggy. The remote capability was not even in the same universe as the Flex 6000 series radios. Interfacing to 3rd party programs on the 7300 had to be done through the old school method of using often hard to find and sometimes flaky 3rd party virtual audio and virtual serial ports. Unlike the reasonably easy to use Flex DAX system. No multiple slice receivers or multiple VFO’s, etc. In my opinion Icom’s  “SDR Lite” is just a “hot mess”. I will reiterate that 7300 is a fantastic rig at its price point, but no where even close to the Flex 6300’s versatility.

Which brings me to the upcoming Icom 7610 at the recently announce price of $3500. Just like when the 7300 was released there will be the inventible endless spirited discussions with comparisons to the Flex 6500. However at this point the 7610 appears to be another Icom “SDR Lite” implementation. The only slightly useful nod to a full SDR implementation is the inclusion of an external display port. This will probably only be useful for display purposes only since there appears to be no mouse or keyboard support. Again no mention of IQ output. There is an ethernet port, but I suspect this will only be used for RS-BA1 remote control. In my opinion at the $3500 the 7610 won’t be a great deal when compared to the Flex 6500. Frankly at the $3500 price point a Flex 6300 / Maestro combination becomes a far more attractive option offering more **** for the buck, far more features, and far more flexibility. However with that being said Icom will probably sell a ton of 7610s and there will be a ton of used 7300s around if you want a good second radio

Ria

I was told that the Icom SDR radios will still use the legacy 36kHz IF. maybe that's why they can't have a full I/Q output.

Varistor

Point and click tuning with a mouse on an external display. https://m.youtube.com/watch?v=r3MF3uwZuIQ&feature=youtu.be

Varistor

This is engineering talk, not user focused talk. Why do you care how the magic happens as long as it does? Most people buy on benefits, not features.

KS4JU

I wonder what their excuse is for not having it on the $3500 7610 Maybe they are afraid they would have to support it with client software. Heck even the $650 Alinco DX-SR9T managed to have IQ output. They even managed to eek out software support in the form of KG-TRX which was fairly minimal.