there is a easy mod in the microphone that consist in remove a resistor and change the value of a capacitor, the result is awesome.
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Ed,
I just had a look at the circuit for V3 of this unit, which is the one you are using. The dc on the mike line from the radio would not affect the compressor chip, which in this version is the ssm2167 unlike earlier versions (2165) because there is a capacitor in the line from the output of the chip to the output connector. However supplying the compressor board with 8v instead of 5v may be an issue, depending on how well regulated the 8v supply is. If it relies on the load in the standard microphone circuit to bring the voltage down to 8v, maybe there is potential for a problem. No pun intended.
This version of the compressor also has a tone generator on board. Nice idea for tuning. (If they had included an option for it to generate a Roger-beep it would have been nice for vhf/microwave users of the 817). But the output of the very basic tone generator does not appear to be filtered enough to cut out the harmonics. (Maybe it is a very high audio freq so the ssb filter will remove the harmonics).
The design shows that the tone is enabled when PTT is already pressed and the Down button is pressed simultaneously. The voltage on the mike line from the transceiver is connected to the output of the 4093 quad chip, via various resistors, this may affect the operation of the tone circuit.
I noted also that they have two RFCs of 10 uH in the input circuit with some bypass capacitors, good to see that they beefed up the RFI suppression, I think it was not so good on my version. Also there is now a warning about using âpoorly engineered antenna systemsâ that do not prevent RF from being present on the microphone line. End fed antenna users beware. The plastic case presumably still does not shield the pcb from rfâŠ
Hope it all works out well, Ed.
Cheers
Andrew VK1DA/VK2UH
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Presumably this mod affects the difference between positions 1 and 2 of the switch on the microphone. The video does not state which position should be used.
Hi Guru - Hi Andrew,
Things seem better now. I did add both a capacitor for isolation, but as you say Andrew this might not have been needed as there is one in the internal circuit, and a voltage dropping resistor - I think it could well be the reduction in voltage that is relevant as now with the DYC turned on I see a little higher average RF level on the meter and when monitoring the audio, it sounds different with the switch set to on, compared to off. As always, itâs difficult to really discern differences in your own voice and see if they are improvements to readability or not when monitoring locally. I have now packed the unit away with the rig ready for when I can get out portable again. Perhaps for the HgOTA / HbOTA event?
73 Ed.
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Hi Ed,
Iâm glad to read that you seem to be making some progress and the DYC-817 seems to be functional. You explained your TX rig was the Xiegu.
What was your output power and your TX antenna?
What was your RX rig and RX antenna?
Were you hearing your own voice on a good set of head phones, on earbuds, on a speaker?
When I run my test, it was not only very obvious and easy for me to notice the difference, when the DYC-817 was ON and OFF, but also when one of the pots was tuned or changed. Not somuch with the other pot.
73,
Guru
I was transmitting 3w into a dummy load from the Xiegu (amplifier turned off). Listening on my IC-7300 with headphones on, using its normal 40m loop antenna. Received signal about S6/S7 - tests done on 40m.
The pre-amp level (P1 control in the diagram) made no difference that I could see to meter levels or sound level. Compression (P2) made some difference to both meter readings and sound.
Compared to when I used to have my DF4ZS RF-clipper speech processor in the microphone on my FT-817, the changes I am seeing from the DYC are not as dramatic but being only a dynamic compressor not an RF clipper, that is to be expected.
Iâll be happier once I get some honest reports when I use this portable.
73 88 Ed.
OK, Ed,
Thatâs clear now. It was a good testing method.
Me too, I hope to try it out next time Iâll be free for a SOTA.
Cheers,
Guru
It looks like Ignacio EA2BD has already kicked off HbOTA
Perhaps we can get some regular skeds and both you and I can try out our DYC-817s ?
73 Ed.
Some few days before our lockdown, I had to dismantle my endfed antenna in the balcony because of the cleanning/restoring/refurbishing works planned for the building façade, so I canât transmit with my FT-817 right now.
However, you could do your transmission and I could listen for you and give you reports with my remote station.
We just need to find the right band, day and time to hear to each other in good enough conditions.
We can discuss it by PM.
73,
Guru
Ed,
Glad to read that the mods have helped the situation. Odd that the gain trimmer doesnât appear to affect the audio much. In that case, having it set lowish is probably safe.
You can buy PCBs with the 2167 chip on them, for adding into a mike case. They donât provide a preamp, so perhaps the 2167 has so much gain already that when driven by a dynamic mike, it can reach its operating levels. So not much gain is actually required from the preamp stage.
The design of V3 still doesnât provide an output level control, which would make it feasible to align the peak output of the compressor to equal the peak output of the unprocessed microphone signal. Using the on/off switch for on air comparisons becomes misleading if the compressor box has a net gain of greater than 1, because the listener or operator does not know whether the louder signal is simply due to the level going up or actually due to the compression. Adding a level control on my unit is feasible, with a few cuts in the board and an extra trimpot.
Cheers
Andrew VK1DA/VK2UH
I activated SOTA yesterday and I did run a brief test with Ignacio EA2BD on 40m SSB transmitting with my Speech Compressor ON, then OFF, then back ON, back OFF and finally ON again. Unfortunately my signals into Ignacio were a bit too weak and he said he couldnât really feel much of a difference between Speech Compressor ON and OFF. At that time I was kicked off the frequency by other stations chatting and producing a QRM against which I couldnât compete with my QRP 5W.
Once I got back home, my friend Javier @EA2GM, who lives in EA1/AT about 500Km West of my QTH in EA2/NV, told me he had been copying me on the Hackgreen SDR and other SDR in Andorra during the test and he noticed a big difference copying me a lot better with the Speech Compressor ON and almost not copying me whenever I turned the Compressor OFF. He also said the modulation was very good when it was ON.
This was very interesting and I want to thank Javier EA2GM for his report.
73,
Guru
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Thatâs a good sign Guru, I hope to test my DYC-817 on Friday from a summit all being well. Previous tests from my side were valueless as with the portable amplifier on (so that I could get a good enough signal through to the other operator to be able to judge if the compressor does anything) I emitted a bad SSB signal. I had thought this was the RF getting into the compressor or the rig itself but after 2 weeks of investigation, I found the real cause. The bias level on the portable amplifierâs final pair was wrong. It was correct according to the set-up instructions but it was actually wrong and the amplifier was going into class B and corrupting the signal.
So (as proved on my activation on Friday) the portable amplifier isnât adding distortion any more, I can again try out the DYC and see if switching it in and out makes any noticeable difference to signal readability.
73 Ed.
Ed,
the value of the compressor is often only seen or heard, when the signal is at or near the intelligibility threshold. Ie. weak. Our findings here are that it makes a big difference to readability. But on a strong signal, the inevitable distortion introduced by compression starts to become apparent and most listeners say they prefer the straight audio. So i suggest you try your tests with weak signals rather than strong.
Hope it works well for you.
73 Andrew VK1DA/VK2UH
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Agreed but it getting over the âin-audibleâ to âJust audibleâ border that is important. Understood that when a signal is loud a speech compressor may well detract from the signal not add to it.
As you know I used to have an RF-Clipper built into my FT817 microphone (still regretting selling the microphone with the rig) - that for me is the âgold statndardâ that I will be measuring the DYC against. The DYC is half the current price for the RF-Clipper - it used to be the same price before that company changed hands shortly before the designers death.
73 Ed.
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Hi Ed,
I saw you on SOTAwatch a few days ago, but I couldnât find you on the frequency from my base station. Did you have any chance to test your DYC-817 from SOTA with your AMP ON and all the stuff? If so, how did it go?
I can tell you that I got a report from Phil @G4OBK when I was activating EA2/NV-116 on 40m SSB and Phil told me he could notice a signal enhancement of something around 1-2 S units when the Speech Compressor was ON with respect to it being OFF.
During yesterdayâs activation of EA2/NV-148, I had a good stream of chasers on 40m SSB many of whom said that my signals were very good. I didnât ask for any comparison report of Speech Compressor ON vs OFF, as I didnât want to break the chasers flow in the pile up.
73,
Guru
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Hi Guru, yesterday I was out on two summits - Iâm not sure if thatâs the SOTAWatch entries you spotted or an earlier activation?
In any case yesterday I had intended testing the speech processor but unfortunately I had larger problems caused by the rig deciding to switch filters and as they are used on both transmit and receive, the transmitted audio became unintelligable and this was after another problem - a connection within a new in-line fuse holder had gone intermittent. So after finding and fixing those two issues, I had no time for further tests. I didnât want to break the flow of the pile-up and worked 50 chasers in 35 minutes on Römerstein - several of whom - having heard my earlier problems, confirmed that the audio was fine and the 70w amplifier was creating a good signal (so at least I know the bias problem in the amplifier is now fixed).
By the time , I got to my second summit the bands were all over the place and so trying any tests from Bussen would have been difficult as there was deep, long QSB and what sounded like rainstorm QRN.
So testing both the internal and external speech processors remain on the âto be testedâ list. Itâs good to hear that you continue to get good reports on the DYC-817. Of course it remains a possibility that using it with mx X108G is not going to provide the same advantage as it does with the FT-8x7 range for which it was designed.
73 Ed.
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