开云体育

Hi All,

Does anyone have floating around in their books a circuit for the
following

Deviation, to be able to get a readout of the amount of deviation into
the repeater RX

****
From a point in the receiver take audio which is squelched amplify it with
an Op-Amp circuit, to prevent loading the take off point, rectify it and the
resulting DC Voltage can drive a meter or with a resistor to ground you can
then sense the voltage drop with an A/D converter to present it to the
controller. You will have to calculate, or determine experimentally, the
value of resistor etc. to get the resultant voltage to represent the proper
amount of deviation. If you use a meter, keep in mind that the mechanical
demping effect of the meter prevents it from giving you a true peak reading.
Use a circuit with a fast attack and slow decay constant to keep the meter
reading from bouncing all over the place.

Freq. offset, I understand there is a way to get a reading so that one
can tell how far off freq. the incoming transmission is.

***
All FM discriminators have a point in their circuit where there is a D.C.
Voltage representing the frequency offset from carrier center. Usually, but
not always, there is a point that gives 0 Volt, compared to ground or other
reference. This Voltage then will become either positive or negative when
the carrier deviates from centre. You can again use an Op-Amp to buffer
this and drive a meter or ADC.

Current, I have a circuit that is a shunt, so to read the amount of
current there is, but how do I get to tranform it to a DC voltage so the
controller can read it.

****
As mentioned before, current becomes a Voltage measurement if you measure
the drop accross a resistor. This can be presented to an ADC. Good sources
to get information on circuits are ARRL handbook, manufacturers manuals to
find the audio and DC Voltage take off points. etc. Application notes for
Integrated circuits used as IF amps, squelch circuits Fm discriminators etc.
are a good start.

73 .. Tony...VE3DWI

At 10:02 PM 3/6/99 , you wrote:

Deviation, to be able to get a readout of the amount of deviation into
the repeater RX

Freq. offset, I understand there is a way to get a reading so that one

can tell how far off freq. the incoming transmission is.

My Spectrum SCR200A repeater receiver has discriminator (center freq.) and
deviation metering capabilities.

The outputs of this could be monitored by the controller, I suppose, and
give you a readout of some type. Maybe voice or CW reading. But my
experience has been that these readings on the Spectrum receiver are only
relative readings, and not very accurate.

You may be able to copy the circuitry from the Spectrum receiver, but it
would not be as simple as just connecting up a few wires. There is
circuitry to drive the meters and calibrate them.

The "on frequency" indicator would probably be the easiest one to
duplicate. Most receivers have a "discriminator" metering point on them
that is used to "zero out" the circuit. All you would have to do is watch
the voltage across a resistor and have the controller report the value.
The controller would then have to report both + and - voltages. Or, if the
controller can't do + and - voltages, you would have to convert the reading
to something like 0 to 5 volts via some circuitry.

73,
Joe, K1iKE

Brent DeSalvo KF4TNP wrote:

From: Brent DeSalvo KF4TNP <Bug1@...>

Have For Sale ::::

Ge Master II UHF Mobile (no PA)

Ge Master II VHF mobile pa

443.125 repeater with RC-100 Controller card
no duplexer

442.100 repeater with no controller
no duplexer

Ge master II vhf front end

Ge control cards, and repeater cards, tone cards etc..

motorola Micor low band mobile

motorola mitrek UHF mobile 100 watts

Johnson Challenger uhf mobile

Johnson UHF 70 watt repeater amp

------------------------------------------------------------------------> Come check out our brand new web site!

Onelist: Making the Internet intimate
------------------------------------------------------------------------> This list is sponsored by the owners and users of "RBTIP"

Request prices/quotes on for sale items. you may email me if you prefer
over one.list

thanks

csinos
wh6um

Since you ask a pretty general question and no two (brand/model) radios are
alike I'll answer with a general overview of what needs to be considered
and addressed when attempting to capture the signal of interest and present
it for conversion at an A/D converter.

To solve the problem I think it helps to understand the factors that need
to be considered in each of these cases.

Deviation, to be able to get a readout of the amount of deviation into
the repeater RX

Assuming you are working with a good receiver with a real discriminator
you'll want to use the discriminator output as a starting point. Usually a
discriminator metering point is available but is a high impedance. You
need to make certain that the circuit you connect is also high impedance or
that you provide a voltage follower (see references below) as a buffer to
this signal. It is generally not a good idea to take the discriminator
output and start dragging it around the inside of your repeater cabinet,
even with sheilded cable. If you feel compelled to do so, at least use a
voltage follower.

That said, I'll let someone else jump in here with their preferred time
constants for this, but you'll have to decide as to excactly what it is
that you want to measure. Peak or average, if average, what time constant
do you apply to the reading (yes peak will also need a decay time constant
but something for arguments sake I'm assuming an order of magnatude here).

Either way I'd suggest a peak detector with a somewhat long decay time
constant.

Essentially you'll want an AC coupled peak detector/rectifier with somewhat
long time constant decay to it (500ms to 1s) to be useful.

See my discussion below on presenting that signal to the A/D converter.

This circuit could/should be connected to the buffered/level shifted output
of the first stage of your next question.

Freq. offset, I understand there is a way to get a reading so that one
can tell how far off freq. the incoming transmission is.

The discussion above about the discriminator output applies.

Depending on the radio, you will find that an on frequency signal might be
zero volts, or some positive (or negative) voltage.

You will also need to know what voltages correspond to a given magnatude of
frequency error. With this information you should be able to calculate how
much gain and offset need to be provided in order to scale it to the
desired voltage range and offset in order to present it to the A/D
converter.

As an example lets assume that your radio exhibits the following:

0 frequency error = 4.5 volts
+5 KHz error = 3 volts
-5 KHz error = 6 volts

At the A/D converter you want:

0V = -7KHz error
2.5V = 0 KHz error
5V = +7KHz error


Therefore the input span is 4 volts for 10KHz and the desired output span
is 5 volts for 14KHz. In other words the input is 400mv/KHz and the output
is 357mv/KHz. Thus you need a gain of -0.8925. Note the negative sign
because an inversion is desired.

Next figure out how much offset needs to be introduced to center the
measurement for the A/D converter:

If we introduce 4.5 volts into the amplifier with a gain of -0.8925 we
would get -4.02 volts from it. So in order to correct this -7.3 volts
((2.5/-0.8925) - 4.5) needs to be summed with the original signal to
introduce the appropriate amount of offset with the signal in order to have
it properly centered at 2.5 volts output.

This all presumes that you are making an error measurement on an
unmodulated (undeviated) carrier. Any deviation on the signal (CTCSS,
voice, etc) will immediately appear at the output of the amplifier/level
shifter. A cheap and dirty way to filter the resultant signal is to
provide a low pass filter before the signal is mesured. The filter's
corner frequency should be low enough that the A/D converter is not
sampling an instantaneous voltage reading that would correspond to someones
voice or to the instanteanous value of a subaudible tone. Assuming the A/D
converter is only going to make one instantanous reading, I would suggest a
corner frequency in the 10 to 20Hz range. (assumes a single pole simple RC
filter). The drawback here is that several time constants of signal are
needed to take a reasonably accurate reading. The shorter the signal, the
less accurate the reading.

Be aware that different transmitters will exhibit varying degrees of
assemetry in their modulated signal (i.e. a sine wave might deviate +5KHz
and -4.98KHz). This isn't uncommon and in this case would add 0.01KHz of
error to a measurement taken as described above.

Current, I have a circuit that is a shunt, so to read the amount of
current there is, but how do I get to tranform it to a DC voltage so the
controller can read it.

The following presumes a negative ground....

This is a fun one.... the easy way is to measure the voltage drop across a
know resistor in the return/ground lead. While there are several factors
to consider when doing this that will impact the resulting accuracy lets
use an example of 1 amp full scale across a 1 ohm resistor giving us 1 volt
of measured drop. If the desired measurement range of the target A/D
converter is 0 to 5 volts then you'd obviously need a circuit with a gain
of 5. Use your favorite op-amp here in a non-inverting configuration with
the appropriate gain resistors to yield this.

Most of the older/cheaper op-amps you will find have limitiations in the
output stage that will limit the outputs ability to swing within a volt or
two of the supply rail. So you will of course be tempted to connect the
op-amps supply to something a bit greater than the desired output. The
drawback now is what happens if something beyond the anticpated input range
occurs. The output will swing beyond the input voltage capability of the
A/D's input and, depending on the input type, could latch up. Minimally
you will forward bias protection diodes within the A/D converter.

The easy way around this is to use a rail-to-rail output op-amp which uses
the same supply voltage as the A/D converters input reference or supply
(whatever is appropriate).

That's the easy one.

Unfortunately you will most likely want to measure current on the supply
(+) side of things. Here you can use the same techniques described above,
but you need an op-amp which has a common mode input voltage range that
includes the positive rail of the op-amp (assumes that the op-amp will run
from the same supply as that being measured and that no higher voltage is
convienently available). Most of the ones that you will find capable of
this are CMOS though there are a few FET input types. Look at product
offerings by maxim (www.maxim-ic.com) or Analog Devices (www.analog.com)
for these devices. Maxim has a few geared specifically towards high side
current measurement.

When working near/in/around/close to/in the presence of RF avoid op-amps
with bipolar inputs. Its not likely you will need the performance
advantages that a bipolar has to offer and many good CMOS or FET type input
op-amps exist today to generally make this a non-issue.

For general familiarization with op-amp circuits a good cheat sheet/cook
book is National's infamous AN-31
(). This shows many common circuit
configurations. Both National Semi and Linear Technology's app notes
(especially those by Bob Pease and Jim Williams [of their respective
companies]) are good resources for ideas and common circuit configurations.



If you'd like to be a bit more specific with the actual voltages and or
current ranges you'd like to convert we can start reducing this to actual
circuits with specific values of components to get you going in the right
direction.


I hope thats a good start of an answer to your question.



--Dave

Hi All,

Does anyone have floating around in their books a circuit for the
following

Deviation, to be able to get a readout of the amount of deviation into
the repeater RX

Freq. offset, I understand there is a way to get a reading so that one
can tell how far off freq. the incoming transmission is.

Current, I have a circuit that is a shunt, so to read the amount of
current there is, but how do I get to tranform it to a DC voltage so the
controller can read it.

By the way, all readings are coming from a RLC-3 controller.

Regards

Kevin.

In a message dated 99-03-06 22:02:18 EST, you write:

<< From: Kevin Mitchell <sparc@...>

Hi All,

Does anyone have floating around in their books a circuit for the
following

Deviation, to be able to get a readout of the amount of deviation into
the repeater RX

Freq. offset, I understand there is a way to get a reading so that one
can tell how far off freq. the incoming transmission is.

Current, I have a circuit that is a shunt, so to read the amount of
current there is, but how do I get to tranform it to a DC voltage so the
controller can read it.

By the way, all readings are coming from a RLC-3 controller.

Regards

Kevin.
>>

Interesting that you should be researching this.. I've wondered the same
thing....
I'll try to dig out my resources and send them to you.....Maybe I'll get
serious about building my own system...

Chuk

I have created a page and posted it on the rbtip website concerning the
large heat shrink tubing as discussed a few weeks back.

Go to

I have also attached the page here for those who did not see it
originally.

Kevin

de Ric KK5RIC wrote:

From: de Ric KK5RIC <kk5ric@...>

I have build four repeaters with the plug in card, they work great.

The plug in mod only takes a few minutes and you do not need to use an
extra jumper to the card.

De Rick kk5ric

At 23:55 04-03-99 EST, you wrote:

From: SS409SS@...



Hi Rich here,

Anyone have the NHRC controller designed to plug into the Mastr II?? Any
feed back on it would be appreciated.. Tnx Richy

------------------------------------------------------------------------

To unsubscribe from this mailing list, or to change your subscription
to digest, go to the ONElist web site, at and
select the Member Center link from the menu bar on the left.

------------------------------------------------------------------------

This list is sponsored by the owners and users of "RBTIP"

------------------------------------------------------------------------> We are proud as punch of our new web site!

Onelist: The leading provider of free email community services
------------------------------------------------------------------------> This list is sponsored by the owners and users of "RBTIP"

De Rick

I am looking for repeaters ready to go, tuned, aligned in any of the
foloowing format:

1. VHF...HIGH BAND (COMMERCIAL) any configuration, with or without
duplexer, single or multi-user. I currently use GE Master II and i am
extremely happy with their performance.

2. UHF...SAME AS ABOVE.

THANK YOU

CHRIS S. INOS
WH6UM

Brent DeSalvo KF4TNP wrote:

From: Brent DeSalvo KF4TNP <Bug1@...>

Have For Sale ::::

Ge Master II UHF Mobile (no PA)

Ge Master II VHF mobile pa

443.125 repeater with RC-100 Controller card
no duplexer

442.100 repeater with no controller
no duplexer

Ge master II vhf front end

Ge control cards, and repeater cards, tone cards etc..

motorola Micor low band mobile

motorola mitrek UHF mobile 100 watts

Johnson Challenger uhf mobile

Johnson UHF 70 watt repeater amp

------------------------------------------------------------------------> Come check out our brand new web site!

Onelist: Making the Internet intimate
------------------------------------------------------------------------> This list is sponsored by the owners and users of "RBTIP"

Brent:

I am looking for repeaters ready to go, plug and do business in any of
the foloowing format:

1. VHF...High Band (Commercial) any configuration with or without
duplexer, single user or community user. I currently use GE MASTER
II and I am very satisfied with their performance.

2. UHF. SAME AS ABOVE.

THANK YOU

CHRIS S. INOS
WH6UM

Tedd Doda wrote:

From: "Tedd Doda" <lazer@...>

On Thu, 04 Mar 1999 23:02:56 -0500, mch wrote:

Can you both post your charts on a web page somewhere?
Perhaps Kevin could put it on the RBTIP. :)

Mine is just a partial drawing, but I'd be more than
happy to post it. I'm just looking into getting a
scanner (the CD-R had priority, hi). If I scan it,
can you post it somewhere?

Tedd,

I can either post it on the rbtip site or you can put it on the shared files
portion of the onelist server. There are 5 megs of space for just that type
of thing. However the rbtip site would have more traffic. I can place a
link....


Kevin Custer
Owner of this list and rbtip.

Rich,
I am using one on a club repeater in S CA. It was easy to install and
setup. I use both voice and CW id's. Will use another one as I do other
repeaters. Good design and now has been up for a little over a year without
any problems.

Allan, AB6UB

Use the shared file area. You access it by
logging onto Onelist and going to the member center page ( go to
< and login, then click the "Member center" button)
click on the repeater-builder link under "List Center" then select "Shared
Files" finally, click "...upload files" and follow the directions.

Now everyone will be able to view or download the information.

Joe wa4nwo

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
Does anyone have any 2 meter HTs or mobile units w/power supply to sell/trade?
Let me know. <a href="mailto:mbiasin@...?subject=2 Meter Equipment">Click
here to respond directly.</a>
<br>&nbsp;
<blockquote TYPE=CITE>-------------------------------------------------------------------
<br>Start a new hobby. Meet a new friend.
<br><a href="></a>
<br>Onelist:&nbsp; The leading provider of free email list services
<br>------------------------------------------------------------------------
<br>This list is sponsored by the owners and users of "RBTIP"
<p><a href="></a></blockquote>
</html>

On Fri, 05 Mar 1999 09:38:27 -0500, JoeD wrote:

Once you get it scanned in, why don't you post it here in the file upload
area?

How? Is there an FTP site we have to upload it to, and
do we have to include a description.txt file?


Tedd Doda CET

packet va3sed@va3sed
e-mail lazer@...

Have For Sale ::::

Ge Master II UHF Mobile (no PA)

Ge Master II VHF mobile pa

443.125 repeater with RC-100 Controller card
no duplexer

442.100 repeater with no controller
no duplexer

Ge master II vhf front end

Ge control cards, and repeater cards, tone cards etc..

motorola Micor low band mobile

motorola mitrek UHF mobile 100 watts

Johnson Challenger uhf mobile

Johnson UHF 70 watt repeater amp

Ray,

We put one in a Mastr II mobile that was modified to 220 Mhz. It works great !

John Lloyd, K7JL

Utah VHF Society
------------------

Ray J. Vaughan wrote:

I have build four repeaters with the plug in card, they work great.

The plug in mod only takes a few minutes and you do not need to use an
extra jumper to the card.

De Rick kk5ric

How about some prices?

Once you get it scanned in, why don't you post it here in the file upload
area?
Joe wa4nwo

On Thu, 04 Mar 1999 23:02:56 -0500, mch wrote:

Can you both post your charts on a web page somewhere?
Perhaps Kevin could put it on the RBTIP. :)

Mine is just a partial drawing, but I'd be more than
happy to post it. I'm just looking into getting a
scanner (the CD-R had priority, hi). If I scan it,
can you post it somewhere?

Mines a copy of copy, but I may be able to redraw it
using StarOffice. Would that be better...


Tedd Doda CET

packet va3sed@va3sed
e-mail lazer@...