CTCSS HOMEBREW

N1RZB

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Dec 18, 2001, 8:26:49 PM12/18/01

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Has anyone built a PL tone circuit for six and two meter rigs that lack a PL
tone?

Any help in any direction would be gratefully appreciated.

Dave, N1RZB

Bob Nielsen

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Dec 18, 2001, 8:52:09 PM12/18/01

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I recall a friend using a neon-bulb relaxation oscillator in a pinch
to create a CTCSS tone. Of course it had a bit of a buzz sound to it.

There are some simple ICs which can be used. I believe the old ARRL
handbooks had a circuit, but haven't looked at a recent one to
see if it still is published. The Communications Specialists tone
boards are a pretty good choice, and at $30 (at least that was the
price the last time I bought one), you can't go wrong.

Bob, N7XY

Gary Glaenzer

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Dec 18, 2001, 8:59:39 PM12/18/01

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"Bob Nielsen" <nielsen@remove_this.oz.net> wrote in message
news:9vors9$3nl$0...@216.39.144.81...

> The Communications Specialists tone
> boards are a pretty good choice, and at $30 (at least that was the
> price the last time I bought one), you can't go wrong.
>

amen

CSI is great stuff

Peter J. Bertini

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Dec 18, 2001, 10:13:07 PM12/18/01

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You can use an op amp in an oscillator circuit (wein bridge?) to do a
passable job.
The waveform must be very clean and free of harmonics, and you have to
inject the
tone at a point in the modulator that will pass it with minimal distortion.
If not, the
tone will be audible (harmonic energy) on the receive end since those
artifacts fall
outside of the high pass audio filtering.

Pete

"N1RZB" <n1...@110.net> wrote in message
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Jim Pennell

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Dec 18, 2001, 10:38:38 PM12/18/01

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One item to bear in mind is how the radio is modulated... If it is direct
into the VCO then the synthesizer loop filter might react to the PL tone and
all sorts of strange things can happen.

This screwed up one rig I added a PL to. Ah well, time to buy a new
radio.

Jim Pennell
N6BIU

Doug Smith

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Dec 19, 2001, 1:43:35 AM12/19/01

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On 19 Dec 2001 01:52:09 GMT, Bob Nielsen <nielsen@remove_this.oz.net> wrote:
>On Tue, 18 Dec 2001 20:26:49 -0500, N1RZB wrote:
>> Has anyone built a PL tone circuit for six and two meter rigs that lack a PL
>> tone?
>>
>> Any help in any direction would be gratefully appreciated.
>
>I recall a friend using a neon-bulb relaxation oscillator in a pinch
>to create a CTCSS tone. Of course it had a bit of a buzz sound to it.

I once built one using a 555. Passed it through a pi-net low-pass filter
(using the primary of a filament transformer..) to get rid of the harmonics.
Worked pretty well - managed to borrow a scope and it really was a pretty
clean sine wave.

But it was connected to a tube-type transmitter, otherwise the CTCSS encoder
would have been bigger than the rig.. Also helped that I had 12 volts of
square wave on the input, I could afford to use a filter with HUGE insertion
loss!
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

budgie

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Dec 19, 2001, 2:06:47 AM12/19/01

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The most common problem I have seen with DIY encoders is insertion
BEFORE the dev control (IDC). The result is that any deviation
limiting strips the CTCSS off the signal waveform. It MUST be
inserted after such processing.

Allodoxaphobia

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Dec 19, 2001, 11:42:54 AM12/19/01

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On Tue, 18 Dec 2001 20:26:49 -0500, N1RZB scribbled:

> Has anyone built a PL tone circuit for six and two meter rigs
> that lack a PL tone?
>
> Any help in any direction would be gratefully appreciated.

KISS. A couple'o wires and a double-sided sticky foam strip:

http://www.com-spec.com/ss64.htm

Skipp

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Dec 19, 2001, 1:48:25 PM12/19/01

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: N1RZB <n1...@110.net> wrote:
: Has anyone built a PL tone circuit for six and two meter rigs that lack a PL

: tone?
: Any help in any direction would be gratefully appreciated.
: Dave, N1RZB

Hi Dave,

It's all a measure of how practical you want to be, more time or more
money. If you want to blow $35 to pick up a Com Spec pl encoder and wire
it in, you wont be sorry. They are rock stable and pretty straight forward
to install. Plus the paperwork is very clear and easy to follow.

If you want to build an encoder... the most practical chip to use is a 555
timer chip. By nature it's stable against voltage changes (it works on
on/off charging ratios) and will put out more than enough power to
modulate even the most stubborn phase modulator.

A lot of people worry about the output square wave, but the circuit I have
uses three poles of RC filtering which clean it up real nice. The result
is a practical sine wave that is relatively stable in frequency and
amplitude.

There are people out there using op-amps set up in many ways to obtain
similar results, but they have problems with frequency drift when the
supply voltage changes a small amount.

I have diagrams for all the above, the classic 555 circuit that I've built
a gazillion of in my day, the op amp version and the single transistor
Twin Tee type circuits. Just Email me if your serious about building one.
(take the NOSPAMPLEASE out of my Email address).

cheers
skipp
http://sonic.ucdavis.edu

Henry Gernhardt/Andrea Winship

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Dec 20, 2001, 6:19:09 AM12/20/01

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Folks---

> > Has anyone built a PL tone circuit for six and two meter rigs
> > that lack a PL tone?
> >
> > Any help in any direction would be gratefully appreciated.

> KISS. A couple'o wires and a double-sided sticky foam strip:
>
> http://www.com-spec.com/ss64.htm

Does anyone have any data on how to wire that unit to an old ICOM
IC-2AT?

Thanks,

Henry C. Gernhardt, III
KE4PIB

Gary Glaenzer

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Dec 20, 2001, 8:56:24 AM12/20/01

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CSI boards used to come with a sheet that gave all kinds of usefull install
info

"Henry Gernhardt/Andrea Winship" <hcg...@earthlink.net> wrote in message
news:3C21C935...@earthlink.net...

carltons

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Dec 20, 2001, 11:02:42 AM12/20/01

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The final problem will be getting the deviation set to the right level.
Nothing sounds better than a 7A tone as someone is talking. Maybe those
new rice boxes aren't as bad as all that, after all. :-)

Steve WB4CZR exMoto eng

In article <c6mU7.126$nxl.7...@news2.randori.com>, "Gary Glaenzer"

N4DKD

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Dec 24, 2001, 2:06:51 PM12/24/01

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This site has several circuits that work.
http://www.rason.org/Projects/projects.htm

--
Brian Wingard
N4DKD

"N1RZB" <n1...@110.net> wrote in message
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carltons

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Dec 25, 2001, 11:03:38 AM12/25/01

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In article <3c203c3b...@news.cantech.net.au>, budgie
<bud...@nowhere.cantech.net.au> wrote:

Modulating the VCO with PL is iffy at best. If you don't end up loading
down the VCO's feedback, you still are adding a low frequency error signal
to the loop which it removes quite nicely leaving you with little PL. If you
are PL modulating a synthesized rig, you should modulate the reference
oscillator and not the VCO.

I've said it a hundred times now. RF is a pain! :-)

Steve WB4CZR
Plantation, FL

Peter J. Bertini

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Dec 25, 2001, 11:41:43 AM12/25/01

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Strange, but that is exactly where most ham and commercial two-way
rigs apply modulation--especially the PL tones--for best linearity.
Ditto for data. The reference frequency is normally high enough that
subaudible tones and voice frequencies are not removed
by the loop filtering.

Peter

"carltons" <mots...@mediaone.net> wrote in message
news:motsteve-2512011105320001@dplane- > Modulating the VCO with PL is iffy

carltons

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Dec 25, 2001, 12:14:40 PM12/25/01

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In article <b%1W7.106471$Y6.10...@news1.rdc1.ct.home.com>, "Peter J.
Bertini" <comm...@home.com> wrote:

This is what is known as two port modulation. The vco has a modulation
frequency response which is a high pass response and the ref osc has a
low freq response. On commercial rigs, you end up doing alot of juggling
to balance the two ports so that you don't get too much of one or the other.

It is a good idea if we leave this discussion in an IEEE forum rather than here.
Back again to the "pain" aspect of all this RF stuff.

Steve