630m and 2200m support?

wb2ems
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630m and 2200m support?

Postby wb2ems » Sun Oct 08, 2017 3:12 am

I have an Anan 200D and with the imminent opening of the two new LoFer bands at 472-479, and 136Khz I'm wondering if the 200D is usable down at those frequencies.

I've been doing some testing and found some stations (Stow, MA primarily on 471) that I can copy on my existing antennas using an rsp1 and sdr-radio v3. Switching to the 200D, I wasn't able to copy the same station at all, although thePowerSDR software seems to understand that I'm in the 630 meter band. I tried a brief transmitting test and was about to get about 20 watts cw into my dummy load, but I'm not sure how good that is for the transmitter - I suspect the transformers aren't very efficient at those frequencies, even if the low pass filters will pass it.

Interestingly, I fired up CUsdr, a slightly older version, and was able to copy Stow with the 200D using that and the same antenna, with about the same quality as the RSP1. So it seems the hardware is capable, at least to some extent. I suspect the poor results with PowerSDR were the result of not having the right RF filters enabled or disabled by the software.

So my questions would be, is there support for these bands in the current version of PowerSDR and the various radios?
Where can I get more information about that?
Is it safe for the radio to use the transmitter at the apparently lower efficiency?
Is anyone else experimenting with this in anticipation of the new bands?

Thanks

WB2EMS
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w-u-2-o
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Re: 630m and 2200m support?

Postby w-u-2-o » Sun Oct 08, 2017 2:07 pm

I have no actual experience with operation below 160M, but this morning I took a look at it just for fun.

Efficient or not, obviously 20W is substantially more than allowed on those bands, so from a TX perspective it seems good to go.

On RX, using the latest version 3.4.2 of PowerSDR mRX, the 8000 I have here, set up for Region 2, seems to "know" about both the 2200 and 630M bands:

- It has them marked out on the panadapter and annunciated in the VFO display
- It remembers my settings for panadapter and waterfall displays
- It seems to bypass the pre-selection filters on RX, and selects the 160M LPF for TX
- Antenna selections for 160M seem to work OK at those freq's (Setup > General > Ant/Filters > Antenna).

I'm located in the Northeast. What would be some good beacons to try to listen to, and what time of day is best to listen to them? I have crazy bad noise on those bands here, mostly from the technology in my own house, but if I knew where and when to listen I'd give it a shot.

73,

Scott
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Mon Oct 09, 2017 3:19 am

Hi Scott,

That sounds about like my experience with the UI, though I didn't know how to verify the filters and other switching. It was interesting that I couldn't copy the station in PowerSDR but could in cuSDR with the same antenna and hardware but could have been that something in the RF path was set different down there and I didn't catch it. But yes, it does seem to know where the band edges and all are.

The strongest station I've heard so far has been the one on CW on 471 khz out of Stow MA. I don't have the callsign handy. I have reports of it being copied regularly in CT, so maybe it's good wherever you are as well.

The antenna efficiencies for most practical antennas are pretty abysmal, often under 1%, so 20 watts won't get you far. Many stations run a couple of hundred watts and some run over a KW to get an ERP in the 1-5 watt range. 20 watts out is a usable start, but if I decide to get very active in the band either I'll need a very efficient antenna or a power amp of some sort. My bigger concern is can I damage the 200D making the 20 watts? I'll have to look at the relative currents from the power supply on 160 meters vs 630 meters at various drive levels to get a sense if there is a bunch of power going in, that isn't coming out the antenna port.

Let me know if you have any luck copying the station in Stow. I think evenings are better, but not sure.

73 de Kevin, WB2EMS
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Mon Oct 09, 2017 7:43 pm

The station in Stow is WG2XSB. Apparently running about 40 watts into a 75 meter delta loop. There are also a number of NDB stations down below 500 khz that can be copied at various locations. Most run morse IDs. Here's a place to ID what you hear by frequency.
http://www.dxinfocentre.com/ndb.htm

73 de Kevin, WB2EMS
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w-u-2-o
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Re: 630m and 2200m support?

Postby w-u-2-o » Tue Oct 10, 2017 2:00 am

Kevin,

I think I have way too much local noise here to receive anything.

73,

Scott
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Tue Oct 10, 2017 3:47 am

Sorry about the noise issues - where are you roughly located? I've got a bunch of noise sources showing up down there, but was able to copy the station in Stow again and this time on PowerSDR when I fiddled with the gain, and removed a bunch of attenuation. Wondering which noise tools would help bring signals up out of the mud. Once I did that, I was able to search around and copy at least 18 NDB beacons between 200 and 400 khz on the 160 loop which is horizontal and very low to the ground. The furthest was in North Carolina and a lot across eastern Canada. Some I'm feeling better about the receive capabilities.

Interestingly in the UI, I noticed in the band button array there is a button in the lower right corner that is greyed out labelled MF/LF. How do we light that one up?

So far the only amateur station I've seen is the one at 471 but maybe I'm not looking where the current part 5 operators are. 471 is outside the new band, just below it, so maybe I should be looking further up as well. I just shut everything down, so I'll have to check that tomorrow night.

Next steps are to build a receive antenna tuner to see if I can get more signal into the radio by peaking the antenna tunng. N1BCG has recommended a simple L network that I i'll try.

This weekend we'll see what we can do about getting a looooong wire up into the trees. I wonder if i can get a 490' wire up over the trees and across some spans. Have bow, will travel. :-)

73 de Kevin, WB2EMs
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w-u-2-o
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Re: 630m and 2200m support?

Postby w-u-2-o » Tue Oct 10, 2017 12:55 pm

Hi Kevin,

I'm glad you are having some success. Obviously attenuator and AGC settings will have a major bearing on that, as well as having the right antenna.

I definitely don't have the right antennas for this. I have a 160M inverted L, which is noisy as hell, just like any vertical, and I have a multiband dipole which is up high, about 65ft. Not to mention too much noise coming out of the house.

Yes, I also wonder what the LFMF button is for!

73!

Scott
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W2PA
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Re: 630m and 2200m support?

Postby W2PA » Tue Oct 10, 2017 5:55 pm

As far as I can tell looking at the code, that button was originally used to select the 2m band (judging by the variable naming convention). Somebody evidently had a new use in mind after implementing the VHF+ button. But as of now, the LF/MF button does nothing but light up when you press it.
73,
Chris, W2PA
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Tue Oct 10, 2017 6:13 pm

Hmmm, I can't get it to light up when I press it. Shouldn't we be able to define a band behind it?

Kevin
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Tue Oct 10, 2017 6:33 pm

Hi Scott,

I don't think anyone has the right antenna for this - after all a half wave dipole would be 1000' long and need to be up 500' :o All the antennas in use are big compromises. So far I've had the best success with my 160 meter horizontal loop which is only 20' high at best. Classic cloud burner. The antennas you mentioned seem about on par with what other folks are using. Sometimes they bridge the coax center and shield and use them like a bit T section. I tried that on the loop with no improvement. Transmit antennas are another whole ball of wax, but most folks seem to be using their regular station antennas for other bands on receive. If I can sort out what's going on with my Pixel loop, I will try that down there as well.

Yes, I didn't realize the attenuation was set to -40 db default when I went to those frequencies. BTW, I'm curious about the attenuation steps. I see they go -40, -30, -20, -10, 0, -20. What's with the second -20? In a different module?

On the noise, yes I think the spectrum is likely to be filled with a variety of things that come from local electronics - but I was pleased to be able to find the NDB's among all the other stuff, much of which was likely noise. I wonder which noise reduction would be best to quiet some of that background. And whether the diversity noise nulling would work down at those frequencies. I don't see why it wouldn't. I may have to experiment.

Kevin, WB2EMS
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w-u-2-o
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Re: 630m and 2200m support?

Postby w-u-2-o » Tue Oct 10, 2017 10:09 pm

Smarter people than I have looked at the code with respect to the extra attenuation settings. Nobody has been able to tell me what they are for. But they do seem to work.

My own pet theory is that they had something to do with the pre-amp on the legacy Flex radios and were accidentally carried over with the old PowerSDR code. The pre-amps in our radios are not defeatable, they are on all of the time, except for the extra 6M pre-amp, which is switchable.

73,

Scott
wb2ems
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Re: 630m and 2200m support?

Postby wb2ems » Wed Oct 11, 2017 3:54 pm

Hi Scott,

Interesting on the attenuator settings. I was thinking that maybe there was attenuation in two different modules that was being selected.

I put the HF-6 vertical with it's protection circuit into the RX2 port and tried diversity last night. I think it's working, but I get kind of odd results. The lowest noise is with the point right in the center. When I flip the reference antenna to the other antenna, I can't get a null at all. I've played with it a bit before and got sort of similar results - it doesn't seem to operate the way I recall the diversity on the Flex 5000 working where I could get very clear noise nulls or enhancements. But something is happening, and that bodes well for future explorations of diversity at MF frequencies I guess.

73 de Kevin, WB2EMS
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Re: 630m and 2200m support?

Postby w-u-2-o » Wed Oct 11, 2017 4:22 pm

At these wavelengths, both antennas will act like point sources, and the point sources will be only a tiny fraction of a wavelength away from each other. If the phase centers of the antennas are, say, 30M (~100 ft) apart, that's only 17 degrees of phase on the 630M band. That means your range of adjustment in terms of forming any sort of beam or null is going to be tiny and generally inconsequential. On 2200M, forget about it!

In other words, it's unlikely you will see any significant effects when playing with beamforming diversity. You might have better luck with polarization diversity (which does not require phase synchronous receivers), however I really don't know enough about LF and MF propagation to hazard a guess on that one.

73,

Scott

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