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RX366 Subreceiver

(comments posted to the Ten-Tec reflector by John Henry)

http://lists.contesting.com/_tentec/2011-12/msg00013.html

The RX366 is only part of a "receiver". It basically replaces the 2nd receiver board in the Orion(s). (Orion(s) in this posting really refers to the Orion 565 and Orion II 566) The RF input to the RX366 board comes from the Orion(s) antenna switch matrix. So you still have all of the "inputs" to the RX366 that you currently have in the Orion(s) to the current sub receiver. The RF input goes to the RX366 Preselector board with an input attenuator and preselector, then the rx preamp, then onto the TXRX board which provides roofing filters and a few other signal related processing items. The RX366 uses its own synthesizer board for LO generation (Fracn board of 599). This Fracn board gets its reference from the Orion(s). So they are pseudo locked in phase. I say pseudo because the alignment of the output of the RX566 is frequency adjustable so that you can fine tune the main and sub rx for diversity reception down to 1/2 hz or so.

The CPUs/DSPs in the Orion(s) control the RX366, set up which filter to use, turns on/off the preamp and attenuator, sets up the reference oscillator for it, etc. The output of the RX366 is 14khz RX IF that goes to the DSP. The DSP then does all software filtering, etc. It does not have any DSP processing included. The Orion(s) processors performs the DSP processing for the RX366 just as it does for the current sub-rx on the Orion(s). This is the main reason I wouldn't call this a real "receiver". Not able to be used on it's own, would require some DSP processing of the output.

Something that I think some customers are not aware of, or have missed, since this is built using the TXRX board of the Eagle, this means that there is a 9MHz output available on a TMP connector. This can be brought out to provide a second sweep on a PC, in addition to the Main RX 9MHz IF output. Can we say "two PC Sweeps" from a single rig?? Now that provides some very interesting possibilities to someone who wants to see two bands full spectrum, but I do admit it will require a hefty PC with a dual high end sound card…. But the possibilities are interesting to say the least.

Regarding kit/with an O2, etc…. Present kit is a set of boards, take out your current sub rx, install/bolt this one in it's place, then master reset, say yes to "RX366 Installed?", set up which filters you have in which slot of the RX366, and you are in business. RX366 will come with one filter, and you can then add to your order filters at the standard price. One filter will come preinstalled in the "kit", and it is a matter of taking out two screws, inserting very easily any optional filters, rescrew down the filter guard, and then you are ready to run. Granted, we may offer at different events/hamventions/etc, packages and incentive pricing, but that is not in the works as of now.

http://lists.contesting.com/archives//html/TenTec/2013-05/msg00164.html

The reason the RX366 doesn't provide AM Broadcast reception as good as the ham bands is due to a broadcast band filter before the roofing filters. This is to ensure that the umpteen hundred gigawatt station 2 miles down the road does not get into the receiver path. You can measure differences in ham bands when the local AM station is at full power in a rig that doesn't have a broadcast band filter. The original sub receiver in the 565/566 was actually the Jupiter receiver, and it did not have a broadcast band filter in line.

What we did fail to realize though when designing the Eagle and it's subsequent reuse as the RX366, is that hams would want to use their Eagle as a high quality AM broadcast band receiver in the ham shack. Me, personally, I'd go down to radio shack and pick up a $12.00 AM/FM/Weather/etc radio for this, and get the RX366 to get the best 2nd rx for ham operations. …. Just my two cents.

For future rigs, we will consider the impact of having a separate path in the preselector for AM Broadcast and treat it as a band of it's own. But that is up to discussion/design/prototyping in house.

http://lists.contesting.com/archives//html/TenTec/2013-05/msg00194.html

One more bit of information on the design that may clear up some points. I relayed this to a couple of other hams earlier in email conversations and thought you all here would benefit from the knowledge.

On receive, in the 599 and RX366, signal comes in, goes through the AM broadcast filter, which does prevent the STRONG stations from coming in on any "path" after that. It won't get rid of them, it just attenuates them to a point where they won't interfere with ham bands. After that, if you go to a band, the rx path is switched to a filter that blocks out EVERYTHING but that band. Meaning, if you select 40, it will block (as much as it can) 10, 12, etc., generally, it blocks other bands and out of band signals from coming through. Now, if you go out of the band, the receive path goes to the general coverage path that lets everything come through, without any attenuation. This is the same path for between bands and outside of bands including the AM Broadcast and SWL sections. But, the FIRST thing that EVERYTHING goes through, is the AM Broadcast band "attenuation".

AM stations can be so strong and if they are nearby, they can cause problems on about every band, even using a band pass filter, that is why we add this "blocker" to the front. It attenuates the signals to the point that they aren't a nuisance to the band paths in the preselector. But it isn't removed enough so that it isn't usable to listen to 930AM.

So, on the RX366, listening to SWL stations is not a problem, the path goes through the AM broadcast filter, then to the open barn door path, so, any signal from any other area outside of the AM broadcast can be tuned to, and can also affect the SWL area. If you have a neighbor running 1500w on 40 or 12 or another "ham band", you may hear distortion from him listening to SWL at 9mhz. But if you are on 12, you shouldn't hear him distort your 40.

And no, none of these filters are perfect, if you have Mr butthead next door to you running 2400w illegally, well, all bets are off, or even 1500w on your block, you may still hear something, but it should be minimal.

On the original sub receiver, there is no broadcast band filter, which means it can affect the ham bands. This is a huge advantage of the original sub receiver over the RX366 in that broadcast band signals are not attenuated at all and can be heard at full fidelity. This is also a huge disadvantage of the original sub receiver in that strong AM stations leak into the ham bands and cause various issues degrading receive performance.

To quantify the differences, compare the Jupiter receiver tests with the Eagle receiver tests. Granted, the original receiver (jupiter hardware) does give a bit better performance due to the DSPs, but generically it is a good yardstick for it.

http://lists.contesting.com/_tentec/2012-02/msg00096.html

The 9MHz IF Output on the RX366 is the TMP connector on the TXRX board (The board with the filters), right next to the F2 filter. If you are going to use an LP-PAN, you should use the preamp offered by telepost. We are modifying the user manual to point out it's location in a picture. Should be available for download in a few days.

update: many users have reported a significant birdie in the 9MHz IF Output that brings into question its use for driving an LP-PAN panadapter. Here's the birdie as posted by VE7TK:



And here's a panadapter display of an empty 10M band, showing spurious signals


Using the RX366 i.f. output to drive a panadapter is not recommended.


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