10E SMA RX Reception OK, main BNC Reception Intermittent - Fixed

rusham
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Joined: Sat Apr 17, 2021 8:04 pm

10E SMA RX Reception OK, main BNC Reception Intermittent - Fixed

Postby rusham » Sat May 22, 2021 9:04 pm

Community,

My 10E has a problem where SMA RX reception is always normal. However, reception using any main BNC input occasionally acts like antenna was suddenly disconnected. A momentary band change or MOX toggle will restore normal BNC reception for awhile. The problem happens more frequently when 10E starts from cold, and less frequently when fully warmed up. To the extent possible, without board removal, all connections have been either reseated or moved a little in an effort to find a bad connection, especially the coaxial jumpers. I have probed all components and pressed the lower board looking for an intermittent connection, component, or trace, and found nothing. I have studied the available schematics. The Anan Amp schematic shows primarily TX paths and no RX. Yes, it shows the SMA RX input but not sufficiently to troubleshoot. The 2011 RX Front End schematic does not include the SMA RX input and while it helps, does not go far enough to trace receive paths. I have asked Apache Labs for 10E specific schematics and received no reply. I did contact W5WC who offered suggestions of reseating a ribbon cable and changing firmware which did not help. Before my unfortunate 10E winds up in a trash can can anyone help with better schematics, ideas for troubleshooting, and so forth. I really like Anan, especially NR2, Pure Signal, and excellent SSB squelch. But entering the Anan ecosphere with my 10E unfortunately has been a rocky road.

73, Russ, K3RH
Last edited by rusham on Wed Jun 23, 2021 4:48 pm, edited 1 time in total.
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w-u-2-o
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Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby w-u-2-o » Sat May 22, 2021 10:57 pm

100% complete schematics are right here:

viewforum.php?f=35

Might be you have a bad relay.
rusham
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Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby rusham » Sun May 23, 2021 12:03 am

Thanks for the link but it seems to point to the same two schematics I have seen and referred to in my message, why I asked for any others out there. Neither clearly helps me to answer my question of why RX input always works but BNC inputs have a problem. One schematic deals mostly with TX configuration in some detail, and the other shows three BNC inputs without RX input. Again, I appreciate your assistance and thanks for the relay suggestion.
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w-u-2-o
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Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby w-u-2-o » Sun May 23, 2021 12:35 am

There are no other schematics. Those two schematics represent 100% of the circuitry in the 10E. They are it. 100% accurate.

Perhaps what is confusing you is that there is no interconnect diagram for the cables that go between the two boards. The best way for you to understand that is to take your 10E apart and see where the cables go.

At any rate, it seems that your problem is on the PA board somewhere, probably a relay.
rusham
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Joined: Sat Apr 17, 2021 8:04 pm

Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby rusham » Thu May 27, 2021 7:32 pm

Thanks for the schematic accuracy assurance. Giving the PA board more study I realized my mistake was thinking RX IN was the SMA RX input, and looking at it that way the receive paths made no sense. It dawned on me RX IN has to be PA board output to main board, then I spotted J3 jumper termination. That cleared up a lot. The only remaining possibilities for intermittent reception from main BNC inputs have to be TXRX relays K5 and K19, but because the PA board is held in place by FET thermal paste I have been unable to bridge those contacts to see what happens.

If anyone has suggestions for breaking FET thermal paste and removing the PA board, then later replacing it with adequately thermally pasted FETs that would be very helpful. And not having IC desoldering tools, ideas for relay replacement would be appreciated. I could cut the pins away and remove them individually, but on a crowded surface mount board, advisable?
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w-u-2-o
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Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby w-u-2-o » Fri May 28, 2021 11:49 am

Not having a 10E I'm not 100% certain about disassembly steps. However, if it is anything like a -100 series, the output amplifier FETs are fastened to the chassis housing which it uses as a heat sink. Simple remove the fasteners on the FETs and the rest of the PA board and lift the board off of the chassis. The thermal paste may have dried up and will stick a little bit, but that's no big deal.

Once the board is out prepare it for reassembly by removing all old thermal paste from both the board and the chassis. Isopropyl alcohol works well for this. When reassembling the board into the chassis you can use any reputable brand of non-conductive thermal paste. The stuff that everyone uses for PC CPU heatsinks is fine, e.g. Arctic MX-4 or the like.

Bridging contacts to see if relays switch is not a definitive test. While the coil may be fine and the contact arm moves, the contacts themselves are usually the fault.

You will not be able to remove and replace the relays without solder rework equipment. It is foolish to try, you will likely destroy the board. The good news is that "rework equipment" for relay replacement is solder wick, solder and a good soldering iron, i.e. nothing fancy.

Inexpensive solder and surface mount rework stations suitable for hobbyist use are readily available on Amazon. For instance this example. Use the right tools for the job. Buy a kit, watch some Youtube videos (search on "solder rework" and "solder assembly") and get some scrap PC boards from old electronics to practice on. You'll be ready to replace a relay the correct way in no time.
rusham
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Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby rusham » Thu Jun 03, 2021 7:36 pm

Scott, many thanks for your very helpful detailed response. I appreciate the time you took to compose it. Because I am not sure relay replacement will be the only thing required, and not having real steady hands nor the best vision, I just sent the 10E to Doug who graciously agreed to take a look at it. If anyone would be interested, I'll follow up with what Doug found.
rusham
Posts: 9
Joined: Sat Apr 17, 2021 8:04 pm

Re: 10E SMA RX Reception OK, main BNC Reception Intermittant

Postby rusham » Tue Jun 22, 2021 7:06 pm

This 10E is now working properly. Doug, W5WC, found an intermittent ribbon cable and replaced the cable and connectors. The 10E has not had a single sensitivity dropout since. Thanks Doug!

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