Santa brought me enough wedge for a left walking boot, somehow I need to find enough further funds to buy the right walking boot. I have a number of QRP transceivers, so maybe I should offer some for sale. I’m not sure if home built gear has much value.
I was rather naughty on Boxing Day, egged on by my sister in law, I ordered a new Mountain Equipment Lightline down jacket at an unmissable price in the sales. My old Lightline jacket has been excellent but looks rather tatty now and the zip broke last season.
My daughter bought me one of those but ready built as a stocking filler, I haven’t tested it yet so it is sitting here on the desk looking accusingly at me - it’ll have to be patient and await it’s turn, I am fault finding with my PSU that stopped working a few days ago! My spare will only let me run the main rig at reduced power.
If you do set up a test, please let me know when Guru and I’ll try to get on with mine as well. I’ve got mixed feelings whether it helps or not but as I changed several things at the same time, I can’t blame the DYC-817 dynamic compressor yet … I’d be interested if either of you get RF feedback into the unit, as that is one suspicion that I have when I have my 50/70 watt amplifier running.
Easily demonstrated with an 817. Observe the power out or ALC bargraph when talking normally with the unit on or off. You can immediately see the effect on the average power.
I’ve rewired it to work with my X108G and while I see an improvement in level, it has been said that it sounds distorted - so I need to play with the levels to see what is possible. I regret getting rid of the RF-Clipper unit that I built into my FT817 microphone and sold with that rig, but that unit is now so expensive (if you can get it). If I can hear how others sound, I have something to go by.
Thanks Andy,
Yes, all on the “test list”. I had hoped to simply install and use it - I set it up by monitoring using 1. another rig and 2. a webSDR - in both cases, it sounded fine to me. Only when I tried using it from a summit, did I get the comment that something sounded overdriven. It’s now set to minimum drive level for the next test. There’s not a lot to adjust in the unit, so i hope it isn’t RF ingress as that can be a pain to get rid of.
I have received a PM from Ludwig @DH8WN sharing his experiences. I can also share it if he is fine with it?
Basically the compressor seams sensitive to stray RF. So a Commom Mode Choke in the antenna coax seams to be recommended.
Ludwig described that in some cases it was no problem i.e. with a 20m band vertical but an asymetrical dipole tuned with a ATU was causing the compressor to cause modulation problems.
He recommends the lowest compression setting to be enough.
When using an external amplifier the problem seams to increase.
We were discussing if a ferrite choke in the cable between 817 and compressor would make even more sense.
It shound be a relatively easy to replace that 8-pin RJ45 cable with another cable adding a ferrites. A normal network patch cable 1:1 should work fine.
So it seams like some tests are needed.
Ed we have a bad skip distance on 20 and 40m as it seams. But to EA it should be perfect.
Thanks Joe,
It’s good to hear that the issues, that I appear to have are being reported by others and work-arounds found.
in my case, replacing the RJ45 cable with a standard IT one with Ferrites fitted would not be so simple as I have modified that lead so that the connections are correct for the Xiegu - who use a different layout than Yaesu do on the FT-817/8. The RF ingress appears to happen even when running the x108G barefoot (but that’s up to 20 watts in any case), not only when the amplifier is running. Perhaps lining the plastic speech compressor’s case inside with silver foil and earthing that may help?
In short: all from the feeding line over the TRX until the Compressor acts as one side of a “dipole” and the Mic cable with the Op as the other side. The Compressor is located in the “middle” and is feeded with RF by this “dipole”.
I’ve decided to make a CMC between the feeding coax and the TRX (or the ATU). My Coax is DXW 174 with a diameter of only 2.9 mm. So I need only a small and light toroid for 4 or 5 turns of this cable.
For 4 or 5 turns of a IT-cable you need a larger toroid with more weight.
It works fine for 5 W. If I’m using my PA with 40 W mostly I have to switch of my Compressor.
If input and output leads are acting as RF capture devices (not a (resonant) dipole - except perhaps on 70cm?) perhaps some RF decoupling capacitors are needed in the design?? The supplied RJ45 cable is flat - so that will be difficult to put through a ferrite core. This unit has been around several years now - I’m surprised that FA haven’t updated the design to address the problems.
We seem tto have hi-jacked this thread. Perhaps a new thread just for the DYC-817 problems is needed?
a happy new year!
If we talk about a resonant dipole than it would be absolutely to short. I think, you mean resonant dipols. But so far as I know structures with two conductiv parts on bothe sides and a feeding point between may be called a dipole.
But further discussions better under the new topic.
Congratulations to all a Happy New Year 2020!
I was glad to find a gift from Santa Claus under my Christmas tree for my SOTA activations, these wonderful and very light headphones!