Flex-ability
Flex-ability
Dispelling CW myths about the Flex-1500
Once upon a time, when the Flex-1500 was first released, there were some issues with USB latency that made it all but impossible to use the radio in CW mode without disabling the internal sidetone and using an external keyer with it’s own sidetone. Fast-forward to the present .... those issues have been long resolved through updates to both the Flex USB driver and PowerSDR itself.
Why then do some people still think that the Flex-1500 doesn’t work on CW ?
I attribute this to a few things. Firstly new Flex-1500 users need to realize that the computer running PowerSDR, hooked up to the 1500 via a USB cable actually implements much of the radio.
PowerSDR is not simply controlling the hardware like Ham Radio Deluxe, it is doing some significant signal processing to implement the radio functionality in software. That being said, this takes a significant amount of computer horsepower to achieve. Fortunately you don’t need a $2000 gaming computer to run PowerSDR. My experience is that the minimum hardware baseline for operating CW with a Flex-1500 has PowerSDR running on a PC with at least an Intel Core Duo (2GHZ) with a minimum of 4 GB of RAM and WIN XP (WIN 7 will work better as WIN XP predates Dual Core technology so it doesn’t take advantage of the full potential of the hardware). A desktop machine will also almost always outperform a similarly equipped laptop machine, so if you don’t need the portability go with a desktop. Refurbished dual core machines can often be purchased for not more than a few hundred dollars. Keep in mind that this is the minimum and as such I recommend dedicating this machine to just running PowerSDR if you want to have good performance. You might be able to get away with running a logging program but don’t plan to have ten other applications running along with PowerSDR unless you plan to use a computer with more horsepower.
If you are planning to buy a new computer then I would suggest you go with at least an Intel i5 processor with 8+GB of RAM and Win 7 or Win 8. My current laptop with an AMD A10-4500m (Quad core) and 10GB of RAM and WIN 8 runs PowerSDR very well, and it cost me less than $500 purchased new. This will give you some horsepower to burn and allow computer logging, digi-mode software, etc to run concurrently with PowerSDR with little fear of messing with the CW performance. Note also that it is not only about raw computer horsepower, some machines have very poor USB hardware and regardless of the CPU, will not work terribly well with PowerSDR and the Flex-1500. Ok, that covers the computer requirements.
I think that the second issue with running CW on the Flex-1500 is that Hams today seem to be reluctant to R.T.F.M. (read the fine manual) and PowerSDR is quite a complicated piece of software. There is such a wide range of PC hardware out there that Flex Radio has configured the Vanilla-PowerSDR (i.e. PowerSDR just installed) such that it will start up and run on almost anything. The caveat here is that it will run; it won’t necessarily run well. This is true for both CW and to a lesser extent SSB. The reasonable assumption made by Flex Radio is that the user will take the time to read the Flex-1500 manual as well as the PowerSDR release notes and follow the procedures documented within both to optimize both CW and SSB performance for the computer that the software is running on. Failure to do so may mean less than stellar audio reports on SSB and issues with sidetone delay on CW transmit (i.e a half-second or more delay from when you depress the key or paddle, until you hear the internal sidetone generated by the rig).
If you read the Flex-1500 manual section on CW and the Flex-1500 part of the PowerSDR release notes (Page 12) they document quite well the three main things that potentially need to be adjusted in PowerSDR to allow for smooth CW operation on the Flex-1500.
(Note that you must STOP PowerSDR to make these changes and then START again to determine how effective the changes are. )
The first thing is adjusting the USB Driver Buffer setting. This is accessed via Setup/General/Options.
It is a slider the goes from Conservative on the left to Aggressive on the Right. You want to make it as aggressive as you can without causing drop-outs or distortion in your receive audio. My suggestion is to adjust the slider only one position to the right
at the time, exit the SETUP, START PowerSDR and listen to a station for a while to determine if the change in settings is causing an issues with receive audio. Repeat this process over and over until you either get to the most Aggressive Setting (unlikely) or you start to hear audio drop out or significant distortion. At that point back it off one position. Resist the temptation to go to the most aggressive setting first as it may cause
PowerSDR to hang up or quit (my experience).
The second is the Audio Buffer size.
Repeat the same procedure as above (i.e stopping PowerSDR, but this time changing the setting to one smaller then Starting PowerSDR).
Setup/Audio Buffer Size - You want this to be the smallest value that doesn't cause drop- outs or distortion on receive. ( i.e. 256 or 128 if possible, but 512 is ok).
Setup/DSP Buffer Size, CW RX (should be 2048) only reduce this if necessary to further diminish sidetone delay. Changing this value to a smaller one will have an
impact on the performance of the narrower CW RX filters. I wouldn't suggest going any smaller than 1024 otherwise you are diminishing performance of
the receiver.
Adjusting the above three settings should give you reasonable performance on CW with no noticeable sidetone delay. For anyone only using a Dual core machine, if this isn't enough there are a couple of other tricks that help, but I only suggest trying these as a last resort.
SETUP/DISPLAY Refresh Rates Main Display FPS (normally 15, can be reduced to 7 with no ill effects). Reducing this should improve the CW performance as it halves the refresh rate on the Panadaptor display, which is quite CPU intensive.
If you are really just running PowerSDR (which is what I suggest on a dual core machine) then you can increase the Process Priority by a notch with no ill effects.
SETUP/GENERAL/OPTIONS Process Priority (I don't recommend going with a setting higher than Above Normal or High, the default setting is Normal).
One other thing worth mentioning is that if you are using the internal keyer in the Flex-1500, be aware that if you enable Iambic sending it will default to Iambic A. Many people (myself included) learned Iambic B and I couldn't send with Iambic A if my life depended on it. The keyer settings are accessed via Setup/General/DSP .
You’ll never get “Ten-Tec QSK” out of a Flex-1500 (it is semi-break in only) but with a few minor adjustments to PowerSDR , running on a suitable computer, you should be able to achieve reasonable break-in performance that is comparable to other QRP rigs such as the Yaesu FT-817.
Cheers
Michael VE3WMB
P.S. A couple of other points to consider .. Virus Protection Software will often kick off a scan on its own. Most Virus Protection programs allow you to temporarily disable this feature (useful when you are contesting etc). Also be aware of the power saving features enabled on the computer (in particular laptops). To be safe I would suggest using a power profile that maximizes performance. Also be aware that some machines running windows will try to sleep USB ports if it thinks that they are not being used, which needless to say, does not make PowerSDR very happy !
P.P.S. The usual disclaimer applies ... I don’t work for Flex Radio and they don’t pay me money to say nice things about them or their products. I am just a very satisfied customer.
Monday, September 23, 2013