Tuesday, February 24, 2009

Dual Diversity

I was calling my buddy Joe on 75 last night. While I was calling I had switched into basically what is the SO2R mode to listen on 160 CW, while I was plowing a hole on 75. I have ADD and I love to do 2 things at once. Here is a shot of the rig running on 2 bands at once. The 2nd RX is on my 160M antenna and the 1st RX is on my 80M open wire fed flattop through a Johnson KW matchbox. The 160M ant is about 80ft from the end of the dipole. I was running 1500W on the dipole. As you can see as far as RX 2 is concerned there is no problem running high power with antennas that close.

When I had my SDR-1000 set up with the Orion, I used the SDR as my DX radio and my Orion as my 75M rag chew radio. I also have another 80M vertical on another part of the property and would either use the flat top or the other vertical for ragchewing, and use the multiband vertical for DXing. With the SDR1K and the Orion I could run 1.5 kw on either rig and not tell the other rig was on the air except on the same band. If I was on 75, I could hear the Orion in the SDR down around 3510 at about S-1 and I could still work DX as long as they were above S-1 using the SDR while blabbing with my friends around 3772. I had the SDR-1000 set up for auto bandswitching of my antennas and I had a no tune amp in the line so it made working DX while shooting the bull with my buddies like catcing fish in a barrell. Point and shoot Bang you're dead. An ADDers nirvana.

I have a couple of N8LP's super fine verctor SWR bridges. The thing had just come out, and I figured out how to use the thing as a field strength device by turning the inputs and outputs around and feeding my antenna into a dummy load. This allowed me to measure accurately how much power was on one antenna while I was transmitting on the other, without any filters or anything getting in the way. The LP-100 is calibrated in DBm so it too was direct readout. I measured about +30 dBm on my vertical when transmitting 1500W on an antenna 80 ft from the vertical. This is what was presented to the input terminals of the SDR-1000. I felt pretty good about that. I could work -128 dBm signals on for example 40M while I had about 1 watt of 80M signal coming down the same pipe and as far as the SDR-1000 was concerned it didn't know I was on the air on the other band. WAYYYY COOL.

Joe and I were shooting the breeze mostly about the economy and how we got here. I actually feel pretty good about the economy. In my opinion this is the worst time to be in cash. Later we started talking DX. Joe had spent a lot of time trying to phase lock a couple of his radios together for true spatial diversity. The F5K with the 2nd RX will do that out of the box. I had never really tried that feature. Joe lives on a ridge top in a million pound stone house called: Stately Johnson Manner up in PA. When he looks east he looks at Europe. When he looks west he looks at JA. His QTH is not on "River Bottom Road". He lives up on: "Way the hell up in the sky" drive. Its an amazing place. On the Manner he has several beverages. A couple of his beverages are pointed at EU far enough apart to make diversity a rational question, and his experiments were to try and phase lock a couple of RX's to make that diversity happen. It was an interesting thing to think about. I don't have that kind of real estate so I didn't really consider it before.

After we signed I decided to give diversity a try. Here is a shot of the F5K set up for dual spatial diversity reception on 160. The station in my cross hairs is IV3PRK blasting away, CQing on CW. The set up is as follows, RX1 is connected to my 80M flat top since that is way I had that antenna configured using on RX1. On RX 2 is my 160M inv-L. The flat top is tuned for 80M. Luis is always strong at my QTH. Last night on my inv-L he was coming in as much as 25 to 30 dB over the noise which was down around -120 dBm. The signal on the 80M flat top (RX1) was considerably weaker due to the antenna and the tuner attenuation, peaking out at -115 to -120 dBm, with the noise down around 130 dBm. I chose this set up so you can see the difference in signals easily. I first tried looking at something on 80 but my 80M dipole is pretty close to my vertical in performance, so I'm not sure the difference would be as obvious. The QSB was definitely different on each antenna and I think it would make a difference. It was late and I needed sleep so I hung it up the night with visions of multi-dimensional QSB in my mind.

To set up the F5K in Diversity mode is easy. You choose the RX1 antenna and the RX2 antenna hit ALT-D and hit VFO sync, and you are there. RX1 and RX 2 both send signals into a stereo space if you are wearing headphones. You can pan either RX anywhere you want in that audio space and you can independently control the volume of each receiver. I could bring up RX 1 or RX 2 and move things around and Luis's CQing was all over my brain's spatial field. It was a lot of fun. I will have to give this a try on some DX sometime that is way down puny weak and see how this plays.

Here are a couple shots of the antenna switching menus. The antenna switch can either be in simple mode or expert mode. In simple mode you can choose what output goes with what antenna. If you are on antenna 3, the radio also can turn an amp that is connected to antenna 3's signal path off and on with transmit. This means if you have the alpha connected to antenna 1, and the Acom connected to antenna 3, when you are on antenna 3 only the Acom will switch to transmit when the radio switches to transmit. You can also determine what goes into RX2 and your choices are to tap to what ever antenna is connected to RX1, to a separate antenna or to Ant 1. In my example I had RX2 set to antenna 1, which is my vertical stack, and my dipole which was on the antenna 3 port was connected to RX1. There is also provision to stick a filter or a preamp in the RX line if you want to do some shaping to the RF prior to in getting to the Tayloe detector. You also have control over "delay". This will allow a bunch of relays to settle down before you transmit so you don't have to worry about blowing up that mast mounted preamp.

In expert mode you have pretty much the same conditions except you can make the choices per band. So for example if you have 160 beverages on the RX input you would likely not want this to be a choice if you were using the ten meter beam.

It's a very powerful switching system and gives you much more power than what I had with the Orion. I think it has great potential for a contest station because changing bands becomes point and shoot.

This is a shot of cross band operation. I know I know pretty mundane. This is one of the real difference between the F3K and the F5K. This is a feature set that is not available on the 3K. The 3 K will have "watch" receiver capability which means you will have 2 software receivers in the pass band of the panadapter, so working DX will be a breeze, but you won't be able to easily work cross band as it doesn't allow multiple antennas etc. I expect if you are using something like a multi-band vertical or a beam there would be some cross band possible, but not with the same flexibility as the F5K

Here is a shot of the program DDUTIL which is a program added to the flex family that adds a lot of functionality. It is written by Steve Nance K5FR. You can take a look at his WIKI to learn all about this program. This shot is of the band following feature of the program. It will send some data out a parallel cable to a switch box so you can have auto chosing of antennas etc. Also it will run your STEPPIR and point your rotor and band switch your Acom 2000 or your Alpha 87A or your Quadra. It has inputs to monitor the LP100 watt meter. Its main feature is you can have up to 4 programs address the F5K at one time. I have 3 set up at my QTH, N1MM DXlab and Skimmer. The software is being written so you will be able to address a whole slew of transvertes. So if you are a VHF UHF maniac this thing will allow basically complete station control over a big time multi-band VHF station. That part of the product is in beta testing right now. Its a very useful add on from someone who is in the Flex community and wanted to be able to develop integrated control for a bunch of his peripherals. THIS IS FLEXIBILITY. This system is fully integrated into PowerSDR even though it is not part of PowerSDR but a separate development. At some point I will write something on the Flex radio community and colaboration.

There is always some new aspect of this radio to explore. DDUTIL will provide for example a great deal of added functionality to the F3K once it is released, so its like getting an upgraded radio for free. No messy modules to add like some legacy radios.

This brings up one last point. If Joe had this radio, I would be able to access it from MY QTH and use HIS beverages way up there on nose bleed ridge, and of course he could use my about" spitting distance from the Atlantic Ocean" verticals at HIS QTH... Let that thought bubble around in your cerebral sauce pan for a minute.... What could you do with a high performance remote receiver????