Episode: 2867
Title: HPR2867: The Kenwood TS940S Automatic Tuning Unit
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2867/hpr2867.mp3
Transcribed: 2025-10-24 12:30:52

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This is HBR episode 2867 entitled The Kenwood DS-940 Automatic Tuning Unit and is part of the series HAM Radio, QSK, It is hosted by MrX, and is about 13 minutes long, and carrying an explicit flag.
The summary is I cover the automatic tuning unit on my Kenwood DS-940 ReconF from HBR 2668.
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Hello and welcome Hacker Public Radio Audience. My name is MrX, and welcome to this podcast.
As usual I'd like to thank the people at HBR for making this service available to us all.
HBR as a community led podcast provided by the community for the community.
That means you can contribute to why not pick up a microphone and give it a go.
We'd all love to hear something from you. If all contributed they below the shows.
Right, this is one of my ad hoc shows.
It comes from response that I got a comment back from one of my previous shows.
It's taken me this long to get around to kind of reading it, and I'm quite bad at replying to comments.
And it's regarding, let me just see what shows are now.
It's regarding HBR2668 explaining the controls on my amateur HF Radio Part 3.
And it comes from, comment is from Michael.
And he was basically saying that it would have been really nice to hear.
I mentioned something about the automatic tuning unit on my amateur HF,
came with TS940S Radio, and that's quite interesting to hear, but I'm not going to do it.
Well, the reason for that was that, as most of the time is a case, I was short on time.
And to do the series, it was all recorded in a one hour, basically.
And I was kind of desperate to get to the end of it and not have to stop in the middle and add a bit on the end.
I guess what I could have done is just record the whole thing and say,
I'm going to set the certain tier and at a later point in time, record it, I suppose,
but I was just a bit short on time.
So I've got a little bit of time today, so I thought I would give you a little treat
and let you hear the automatic tuning unit on my came with TS940S.
So I've had to, as I previously said, my amateur HF Radio Station can cause interference
and set downstairs, nobody else is in the house, so I had to unplug the power cord
from my television set, so it doesn't power itself on, which is a bit bizarre,
but it does, it powers itself on if I start transmitting really strange.
So it's obviously RF getting in somewhere, but it's unplugging and it's fine.
This doesn't seem to affect anything else in the house.
So, and the next problem I have is that my PC doesn't, the PC's not near the radio
and my headphones, I've got, I'm wearing headphones with a boom microphone,
it's a gamers headset, very cheap thing, nothing expensive at all.
And it won't reach the radio, so I'm currently using an old Samsung netbook thingy,
a really old thing that it runs the Ubuntu and Audacity.
I'm running Audacity just now and it seems to run it very nicely,
so that's what we're using, our transfer to the PC and edit it at the end.
But anyway, I digress greatly.
So, I've got the radio here in front of me and I'll just click it on.
Yeah, so it took a while to come on as you noticed.
So that's it on and I'll just turn the volume down and let's just see.
Now, I've just tuned it up just to make sure it was working before I recorded this.
And it does indeed still work.
It's very mechanically and mechanical and there's really,
a lot of delays and kicking and groaning as a cogs turn round and whatnot inside the thing.
And I did think, it's not, I mean, I don't oil it, I don't do anything to it.
It's amazing, it wasn't jammed.
It was a bit slow turning when I first tried it, but anyway.
So, we're currently on 7.19o, 7.19o megahertz.
So if I just push my voice button, oh no, that's the wrong button.
It's this one here, isn't it?
7.19021.
So there you go, that's where we are.
That's where I tuned it up on.
So, my antenna, which is in the loft, it's a halfway dipole,
it's just two pieces of wire, basically.
It won't cover the full, if, um,
full split of the band, which is a 40 meter band, 7 megahertz,
as I've got a wavelength of approximately 40 meters,
which is why you call it the 40 meter band.
And, um, so, if I tuned it to kind of round about the centre,
which is 7 megahertz, so we'll go down from 7.2 to 7.
I'll just turn that down, or thereabouts.
There's nothing but noise, rubbish on at the moment,
there's nothing to, interestingly, let's not just let you hear
there's a spinning thing around down.
And then, something there.
I've got that wrong, sorry, I'm going to, the centre is 7,
yes, 7.1, isn't it?
So, because the band is 7 megahertz, that's right.
So, between 7 and 7.2, so 7.1 is kind of in the middle.
So, if I, and I just check, there's nothing there.
So, there's, there's, um, the ATU button,
it's called, it's, um, it's, the, the legend on it is,
AT.T, antenna tuning unit, dot T, all the T sounds for,
but, um, yeah, so, when I push that button,
it must change the receive path in the radio,
and you hear a, I like clicks from the receiver,
but from the, from the relay clicking inside the radio.
And, it sounds funny, if, if, if there have been a,
um, a conversation on, you could have heard it,
but there's really nothing on the band,
it's just very nice, it's very noisy just now.
But, when you push it, it, it, it says, um,
antenna tuning unit, antenna tuning auto tune ready,
and it, and it, maybe stays for five seconds,
and then reverts back to, it's normal states.
You want to go so long to transmit,
once it's transmitting, that'll then time tune, tune up the radio,
but if you don't transmit within a set number of seconds,
it will, uh, drop back out.
So, I'll just turn the volume up so you can hear it,
and then I'll push the button, so you can hear the,
maybe hear a difference in the audio,
you maybe won't, I don't know.
So, we're going to push it now.
That's it.
And, that's it, go back again.
So, you can probably hear it switching from one to the other.
So, I'll do that again.
So, you can hopefully hear the, hear the difference there.
Um, so, what I've got to do,
I'll just pick up the, the hand of microphone here,
and, uh, what I'll do is, I'll, uh,
push the AT.T key,
and then within five seconds or so,
push the, um, the, uh, PTT switch,
the switch on the side of the microphone,
hand microphone I've got here,
and that will activate the transmitter on the radio,
and it will try and tune the load.
Now, I'll just, out of interest sake,
uh, I've got the radio switched to the SWR position,
and if I click the transmitter,
and I'll just give it a tiny, tiny wee,
I'll just briefly speak into the microphone
and see what sort of reading we're getting in SWR.
Uh, so, where is the SWR scale?
Is, ooh, I need to get down,
because I can't see it from here.
Oh yeah, so, okay, here we go.
It looks like it's 2.5,
uh, so the SWR is,
it's setting about 2.5,
2.5 to 1, is it?
I think that's what you say.
So, um, yeah, that's,
that's too high.
You want it barely to move, really, ideally.
Um, so, what I'll do,
I'll just push the AT.T,
and then I'll push the button on the microphone,
and you'll hear it grinding and crunching away as if.
It won't be very long,
because it doesn't take it terrible long to,
to find the tune points.
So, here we go.
You're pushing AT.T now,
P.T.T.
And it says tuning finished TX ready,
and then this display just goes back to the,
to the clock or whatever it was set to.
Now, if I push the P.T.T again,
and give a brief whistle,
or a brief noise,
yes, 1.2,
1.2 to 1, as opposed to 2.5.
So, there you go.
It's tuned the radio up.
Um, uh, that's it.
So, uh,
but you couldn't wait for that noise.
It was, uh,
you were riveted to your seats,
and apologies.
I should have really included it.
I knew that at the time,
but as I say,
I said previously that I was,
I was short on time,
and that's always the difficulty.
I got a certain period of time
to do my recordings,
and then I do it.
And then it comes to show notes,
well, you know,
you can, you can stop and start
to show notes as you like,
but when you're recording something,
you really want to get,
uh, down in a one hour sort of thing.
So, where that,
that's the way it goes.
Phew, well, there you go.
I thought this would take about two,
three minutes,
and we're now at,
I'm now at nearly 11 minutes.
I almost forgot,
um,
Michael also mentioned about,
uh, not giving an example,
about the, uh,
operation of the noise blanket,
on, uh, the radio.
Um, the noise blanket,
uh, is used to, um,
strip out, uh,
short, um,
pulsed type interference,
that, uh, you get on the radio.
Um, there's,
there's two noise blankets on the radio,
uh, one,
I think it's for,
really, really,
fast, short,
pulses.
And,
my second one's for,
a longer pulses,
I think, from memory.
The trouble with this is that, um,
it is, uh,
I need to hang around waiting for
pulses like that to appear,
so that I could use the noise blanket
and find it.
So, um,
it's kind of a wee bit in practical.
I, I, I,
maybe I could,
around the internet and find examples
of a noise blanket.
And I say it often,
these things don't work terribly well.
And,
they don't work fantastically well
on the 9,
on the 940,
but they work better
than I've experienced on other radios,
let's see.
Um,
sometimes it's really good,
it works quite well,
but as you,
it might have an idling car outside
and,
and this back of the nation,
uh,
causes,
sort of ticking noises on the radio
and pushing the noise blanket in it
and adjusting the,
how,
how aggressively it takes out, um,
sort of, um,
you can,
remove it basically.
And you're almost,
don't notice the,
the missing bits of audio
that are,
that are taken out.
Um,
so, yeah,
it was lack,
lack of time again.
Well anyway,
I hope you find that interesting.
And until next time,
I'll sign off,
this is MrX,
signing off.
If you want to contact me,
you can contact me
at MrX,
at HPR,
at GoogleMail.com.
That's MRX,
80,
HPR,
the At Symbol,
googlemail.com.
So until next time,
thank you,
and goodbye.
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