Monday, April 27, 2009

Of ZL's VK's and Summer Time Static

Here is a shot of the F3K console. It looks just like the F5K console, and that is because it is just like the F5K console. There are a few things missing, for example there is no "Antenna" sub screen since there is only one antenna port, and the RX2 aspect of the program is dormant, but otherwise it is pretty much exactly the same. Because it is the same, the performance between the 2 radios is virtually identical I have grown accustomed to the dual receive in the 5K, and the ability to control multipe antennas and signal paths. I have 3 seperate antenna/Amp combinations set up on the 5K as well as a couple seperate RX antenna scenarios, so I can DX while I am ragchewing on 75, or run SO2R. This is impossible on the F3K without making it happen with external complex switching schemes. That is the power of the F5K it allows you to multiply the functionality of the station right out of the box without going through that design nightmare.

I have all my rig connections coming out to a patch panel. On the panel I have 5 outputs from the F5K, one output from the F3K, one output from the SDR-1000 an output from the Paragon and an output from a six meter transverter. I also have I/O from 4 linear amps and 2 N8LP wattmeters, and an Ameritron tuner that show up on the panel. I have a seperate panel that allows me to chose which radio controls which amp. The F5K allows for automatic control of 3 amps, so when I want to use antenna path 3 for example I just click "ant 3" and the entire line from the radio to the amp to the antenna just comes on line. It is super convienient and super functional. If I am on ant 3 and I want to listen to a seperate RX antenna for RX2, I just click that in the ant screen and it become active. I don't have to unscrew antennas from the patch panel, or fiddle with antenna switches or any of that, just a click of the mouse and I go. This feature and the SO2R aspect is something I had some input on when the design of the 5Kwas being brainstormed, and Gerald has implemented it to a T.

The 3K is more simple. If I want to rag chew on 75, I connect my 75M Flat top to the patch panel, connect the F3K to the correct Amp, and rag chew. If I want to work DX I unscrew the flat top, screw in the verticals, change the patch panel amp control to the amp that is in line with the verticals and have at it. Much of the advantage of the F5K could be recovered using the macro function in DDUTIL and a bunch of relays, but not all. But if you leave out all this fancy station control and complex operating techniques like separate RX antenna and dual diversity reception, what is the radio's general performance?

I have been on vacation for the past week. We are at the end of my house remodel so I haven't been getting up to listen to the bands, I've been enjoying sleeping in a little before the hammering commences. Today was my first day back at work so before I headed out the door I took some time to listen to the south Pacific to hear what I could hear. ZL2AL VK6DU were coming through. The band was full of summer time static. The storms out in the Atlantic were doing their thing. Band noise was running -100 to -96. My usual band noise is on the order of -118 to -120. Above is a shot of ZL2AL just a tiny bit out of the noise, he was running -96, and the VK6 was about -98. With the F3K I was able to adjust the AGC-T and audio gain to make them Q5 no problem. I didn't even have to narrow the bandwidth below 100hz. I am not able to A/B the F5K and the F3K on the same computer because the driver won't support 2 instances of the radio simultaneously. Eventually this may come to pass, but probably NOT until the new version of the software is released. But given my hours and hours of experience listening to weak signals using the F5K I am confident there is virtually no difference in the ability to copy puny weak signals from half way around the world.

As I have said, I consider this radio system to be essentially a dual conversion radio, with the first conversion done in hardware and the second done is software (actually I consider everything before the A/D as the first conversion and everything after the A/D as the second, but the above description is close enough and easy to understand.) I never put anal perfection before clarity of thought. The second conversion aspect is identical in the 2 radios. The A/D itself is a stronger chip in the F5K, so things like dynamic range are stronger in the F5K, but in the 3K they have done an interesting thing. Included is a hot preamp and an attenuator of different strengths. What this allows you to do, by adding and subtracting gain is to center the dynamic range according to the band conditions. On a very quiet band you would turn on the preamp and thus plunge the dynamic range down into the noise to hear the weak one. On a band like 80M where noise abounds (especially this time of year) you would either run with no gain manipulation or you would add some attenuation to increase the dynamic range a little. Frankly I have never seen either this radio or my F5K overload, unless I specifically set out to overload it, but from an engineering standpoint I am glad Flex addressed this issue. The F5K has something like a 7dB stronger dynamic range compared to the 3K. The 3K is about as strong as the Orion.

So what's the upshot of all this? The upshot is the 3K is too cool. You get performance as good as an Orion, for like 1/3 of the money when you consider adding a couple roofing filters etc. You get a better bandscope and tuning scheme, and better filtering and a quieter receiver and greater control over how your radio sounds for 1/3 of the money. It is true you can run the Orion without a computer, but no one runs without a computer in the shack, and I saw a core 2 duo laptop with a 14" screen from Gateway advertized for $399 that will make this radio get up and do the boogaloo. (I remember the boogaloo: scary)

I had the radio running all weekend with the latest bleeding edge alpha code SVN version and it was rock stable all weekend. Not the first hint of a hickup. Flex has come a long way!!