Stereo Diversity and Split mode operation

Joe-W4WT
Posts: 66
Joined: Sun Apr 09, 2017 5:27 pm
Location: Cumming, GA

Stereo Diversity and Split mode operation

Postby Joe-W4WT » Fri Nov 23, 2018 2:20 am

I have been using Stereo Diversity on 160m now that we are in a new season and find it very helpful as I have a low noise RX antenna and couple that with my vertical transmit antenna and find frequently it reduces fading considerably by listening to both antennas. The problem was Split operation while in SD mode. I know Gary, K9RX, had found a method that worked but I wanted something easier to use.

I first found that when you have the SD button enabled, it will not let you select Split mode. Turn it off and Split can be selected normally. The next thing I found is that there appears to be nothing the SD button really does other than block Split mode. If I turn on Rx2 and select Split everything works just fine including the Stereo Diversity functions, as far as I can see. The transmit frequency is below VFO A's frequency and right clicking twice to get up the red cross hairs allows you to click to set that transmit frequency to what you want it to be. To make it "look" right, you can, after Split is selected, click on SD and lo and behold it will select then! Odd.

So, the question I have is this way of operating Split mode while in SD mode kosher? I can't find anything that doesn't seem to work and it is simple to set up. Anything going to blow up or otherwise cause havoc on the bands?

Joe W4WT
K9RX
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Joined: Fri Apr 14, 2017 3:47 pm

Re: Stereo Diversity and Split mode operation

Postby K9RX » Fri Nov 23, 2018 2:04 pm

Joe,

Because of the awkwardness of SD I gave up on using it... also I was never able to get a decent SD result using my 85' vertical T TX antenna and the 8-4 vertical RX array. Also I found out, contrary to the schematics, that the ANT3 input does NOT ground the input when in TX - thanks to Doug for pointing this out. So I moved the RX antenna to ANT3, set that as the RX antenna on 160 and use it only for RX. [no updated schematics are available per Doug]

Now the downside. I was sure that the relay was grounding the input (again, as shown in the schematics) because my RX preamp was blown last time I tried a connection to ANT3. But since it physically is not it had to be some issue with how the relays are transitioning. Doug worked on it and found that RF was present on the ANT3 input when first going to TX for a brief period when the Key-Down setting was less than 17mS (I had it originally at 7). My concern and reason for the lower setting was that this truncated the first element but having a local ham test/listen we found at 34WPM there was no lost element with a setting of as much as 40mS. So I set them both, Key-up and Key-down to 30mS....

But NOW the issue is I get false "HIGH SWR" showing on the screen occasionally and the display on the front panel of the 8000 shows HUGE full scale spikes on the REF bar! So whatever the issue is it's still not resolved. Also because the radio appears to 'react' to HIGH SWR, even what appears to be false one, it seems to modify the signal output or at least it appears as such using DUP and looking at my TX signal. So it's an ongoing concern.

I'll look in to trying your method. It's been since last season but if I recall the only way I found you could do SPLIT and SD was to use XIT. It's a bit of a PITA as the tuning is so slow but it generally is a one time setting in the region of split TX and from there a relatively small change ... although at times you can tell the DX went from listening at the bottom of his range to the top which can be as much as 8Khz (and more) ... NOT a trivial amount of tuning on the XIT. I had in my list of "requests" asked that the red (right click) cross be used to set the XIT frequency when SD is selected ... ideally since RXB is not being used when in SD one would think it could be used for setting the TX frequency when SPLIT were turned on, that would be even better ... if adding in RX on that split is the issue with doing this I believe just using the Pan display and more quickly being able to select the TX frequency, sans the audio, would be a usable fallback.

Gary
K9RX
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w-u-2-o
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Joined: Fri Mar 10, 2017 1:47 pm

Re: Stereo Diversity and Split mode operation

Postby w-u-2-o » Fri Nov 23, 2018 2:35 pm

Joe-W4WT wrote:So, the question I have is this way of operating Split mode while in SD mode kosher? I can't find anything that doesn't seem to work and it is simple to set up. Anything going to blow up or otherwise cause havoc on the bands?

Joe,

You are not going to break anything or cause any havoc on the bands.

There is no magic in SD. It is exactly the same as MultiRX except the receivers are phase locked.

Gary and I had a lengthy discussion of SD in this thread that you might find interesting:

https://apache-labs.com/community/viewtopic.php?f=21&t=2362

73,

Scott
Joe-W4WT
Posts: 66
Joined: Sun Apr 09, 2017 5:27 pm
Location: Cumming, GA

Re: Stereo Diversity and Split mode operation

Postby Joe-W4WT » Fri Nov 23, 2018 7:29 pm

Thanks for the comments Scott and Gary.

My "gloom and doom" was really tongue in cheek. As I mentioned, I really don't see that the SD button does anything other than block you from selecting Split. It does not cause the vfo's to sync on my radio . I have to press sync manually. I worked a couple of stations last night using Split with the SD button off but using "stereo diversity" with apparently no issues.

Gary, I also use Ant3 as my Rx antenna port since Ext2 has 20db of attenuation associated with it. Interesting info on the "key down" setting. I've never had that below 20ms though.

I use the Anan 200D filter/antenna board with my "hybrid" system using the 8000 transceiver board so my experiences may not be the same as someone with a "proper" radio sees. I also don't have any grounding for Rx ports but so far that hasn't been a problem as my Rx system has a controller that limits the amount of Rf going into Ant3. However, I think it may be prudent to rig something up to do the grounding of that and Rx2 for the future.

Tonight I'm going to do some testing to see if you can have two different Rx antennas connected and use them for stereo diversity while using a third antenna for transmit. I think that will work by putting a Rx antenna on Ant3 and selecting it for receive, another Rx antenna in Rx2, and the main transmit antenna on Ant1. We'll see. My transmit antenna is the shunt fed tower and it is very noisy on Rx. I have a good Rx phased loop array but might want a second Rx antenna to work on different arrival angles for the diversity setup.

Joe W4WT

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