LDG RVS-8 User manual

LDG Electronics

1445 Parran Road St. Leonard MD 20685

Phone: 410-586-2177 Fax: 410-586-8475

e-mail: [email protected] Web site: www://radix.net/~ldg

RVS-8 Repeater Voting System

Assembly Manual Ver 2.1

Introduction: The RVS-8 is a full featured repeater voting system designed to work with today’s amateur

and commercial repeaters. The voter features 8 channel capacity, menu driven display system, programmable

logic states, on screen “signal to noise meter”, site activity logging and more.

Once installed, the RVS-8 provides signal to noise based, “real time” automatic audio switching for up

to eight sites. Multiple RVS-8s can be cascaded to provide up to 64 channels of voting.

Building the Kit: The RVS-8 is a medium to large sized project (not for beginners). It may take the average

builder several evenings to build, check out and align the voter (we averaged about 3 hours for assembling just

the PC board). Besides the normal building tools needed (small soldering iron or soldering pencil, wire

cutters, screw drivers, etc.), the only test equipment needed is a voltmeter or oscilloscope.

Kit Assembly: Before starting, you may want to get a copy of the QST article where the RVS-8 first

appeared. Although not needed for construction of the kit and written for an earlier version, it contains a little

more general information about the RVS-8 and how it works. If you don't have or can't find the article, a

reprint may be available from QST, 225 Main St., Newington CT 06111. We've included the updated charts,

tables and information from the article in this manual.

Changes from the Article: A few changes were made since the article. The PC board size was increased to 6

by 9 inches. After building several prototypes (including the one shown in the QST article), it became

apparent that component spacing was too tight and the PC board was expanded for ease of construction and use.

A larger LCD module is now provided. We were able to find a source of larger, back lit LCD modules

with connectors that fit in the same vertical space. The new module is more readable and easier to connect. The

78L05 was also upgraded to a 7805 with heatsink to handle the extra current required of the back lighting.

The control circuitry has also been changed slightly. A new schematic is provided in this manual. An

LM339 was added in place of the transistor for the COR and DIS Select line. This provides smoother selection of

the multiplexed input bus and a driver for the output selector. A current limiting resistor was also added to the

+12 line of J6 to prevent resets in case of shorting.

All of the LM324s were upgraded to TL084s. The new chips are a direct replacement and offer much

less crossover distortion than the 324s.

U7 was changed from a CD4051 to a MAX 4051. The change provides an extra 20 db of cross talk

isolation. The chip is a direct replacement.

J3 (Disable input) was upgraded from a header to a screw type connector. There was extra room on the

board.

Be sure to use the schematic, parts placement, and connector pinouts provided in this manual. It

matches the latest PC Board layout. Those items in the QST article are now outdated.

The software changed somewhat from what was described in the article. All references to db have been

eliminated. We found it was possible for users to properly calibrate their system, but still not get accurate db

measurements on the LCD module. All references made to signal strength, hysteresis, and S/N ratio are now

relative references (shown as numbers, instead of db).

Getting Started: Before getting the soldering iron out, go through all of the parts in the kit and familiarize

yourself with each component and its placement. Most of the parts are common, but a few of them may be new

to some builders. There are just over 200 parts and 850 solder connections, so take your time.

Once familiar with the parts, use the parts placement sheet in this manual for identifying parts

locations on the PC Board. Installation is done in order of vertical height. That is, the parts with low profiles

(like resistors) are put in first and you work your way to the tallest parts (like the relay).

With the PC board blank, it is easiest to install all of the individual resistors first (not the SIPs). Be

sure to check the values with the parts list. We provide 1/8 watt resistors with the kit, but you may use 1/4

watt if you wish (you may have to reshape the leads of the 1/4 watt resistors to make them fit). You can install

the resistors in groups (like R25-32, R33-40 and R49-56) to better keep track of your progress. There are

34 total.

Diode 1 and 2 are next. D1 (the larger 1N4001) goes near the 12 volt input. The smaller 1N4148 goes

near where the relay K1 will go. Be sure to match the polarity.

Now the 0.1 uf caps. There are ten that are randomly scattered on the board and another eight in a nice

row at J5 (Audio In).

Now the Resistor SIPs. There are seven of them and two different values. Be sure to note the polarity of

these. While looking at the SIP package and the markings are facing you, pin 1 is on the left side. It may also

have a dot or line to mark pin 1. Note that the Resistor SIPs are called RS1-7 and the Resistor DIPs are called

RP1-5. For markings, 103 means 10K and 104 means 100K.

Then the crystal. Use a left over piece of resistor lead to tie it down with holes provided on either side

of the crystal. This will keep it from getting moved around too much and possibly breaking the leads.

The DIP sockets go in next. Note that all DIP sockets have pin 1 toward the top or to the right of the

board. Both PLCC sockets have a small arrow in the middle area of the socket that points to pin 1. The arrow for

the 52 pin PLCC should face toward the top of the board (flattened corner will be toward the crystal). The

arrow for the 44 pin PLCC should face toward the right side of the board (flattened corner will be toward U6).

The 18 pots snap into the board. Be sure not to fold any of the pins underneath (and out of site) of the

pot. All the values are the same, 100K (marked 104).

There are two transistor looking devices (TO-92 package) that go next. One is a 34064 power

supervisory chip (U4) and the other one is actually a 2N3904 transistor (Q1). Both of the TO-92 devices face

(the flat side) toward the left side of the board.

More capacitors are next. Install the twenty four .0047 uf disk capacitors and the two 22 pf (C51 and

52) near the crystal (the actual value can be anything between 10 and 33 pf). Install the 1.0 and 10 uFs (the

electrolytics) in groups (C9-16, C41-48) to help keep track of them. Be sure to note polarity of the

electrolytics, the long lead is the positive.

Use a nut and bolt to tie down the 7805 and heat sink in place. Configure the bolt so that the head is on

the bottom of the PC board and the nut is on the component side. Form fit it before soldering in place. You may

want to use a small amount silicon ”heat grease” to help the heat transfer, but it is not required.

The remaining components are connectors, headers, the relay and mounting hardware. Install the relay

last. The screw terminal connectors are made by sliding a several connectors together. J1 and J2 is made up of

two 2-position and one 3-position connector. J3, J4 and J5 is made up of three 3-position connectors. Be sure

to install the screw terminals so that the wire will enter from the back of the PC board and not over the

components (they

will

go in backwards). There is no connector for J7 (the six pin User Interface). You can

either solder the wires directly to the PC board or use your own SIP style connector.

The circuit should be “power on” tested once all components are soldered in and before any chips are

placed in the sockets. Do not connect the LCD module yet. Apply 11-15 volts DC to the power input, J1.

Current draw to the unit should be around 40 mA. The relay should energize.

There are voltage test points marked for +5, +6 and +12 volts just above U1. The test point for +12

will read 0.7 volts lower than the power input voltage applied at J1 because of the blocking diode D1. This

diode prevents damaging chips if you accidentally connect input power backwards. The +6 test point will read

half of the +12 test point (it doesn’t have to be exact, +/- 10% is ok). The +5 test point should read very

near 5.0 volts (4.9 to 5.1 is ok).

Now install all chips except U1 and U2. Be sure to note orientation. Note that some of the chips are

CMOS types. Although today’s CMOS chips are well protected, some care should be taken to be sure the chips are

not damaged by static when they are handled (Don’t wear a wool sweater, brush your feet across the carpet, pet

a cat, then try to install the chips). Reapply power. The voltage check should stay the same and the current

draw should be around 80 to 90 mA. The relay will still be energized.

If the volts and amps still look good, you can proceed to install U1 and U2 into the sockets. Notice that

U1 and U2 has a flattened corner that should match the socket. Also, U1 and U2 have a small dot denoting pin

one that should match the arrow inside the socket.

Connect the LCD module using the supplied cable. Orient the LCD module so that the display is facing you

and the 14 pin connector is on the left. The red stripe on the ribbon cable should line up to the left side of the

PC board (closest to U2 and the Contrast pot) and to the bottom of the LCD module. On power up, the RVS-8 will

display the startup screens on the LCD to show that the microprocessor is running and everything has

initialized successfully. Current draw should be around 250 to 300 mA.

The display will show two startup screens in succession. The first will be the unit identification. The

second will be the software version number and version date.

Repeater Voting

System RVS-8

Version 2.1

March 1997

After two seconds, the display will switch to the Current Voted menu, which is the default display. If

you are successful in getting the LCD to display the menu system, you can proceed with mounting the unit in an

enclosure and connecting to the user interface.

The RVS-8 fits nicely into a rack mount box (one rack unit in height), but just about any metal

enclosure that will accommodate the PC board and front panel items will work. Custom enclosures (pre-drilled

and punched, painted and silk screeened) manufactured by Ten-Tec Inc are available from LDG for $65 (plus

shipping) .

Switches 1-4 and LEDs 1-2 mount on the front panel. The toggle power switch, SW4 is the only switch

that will have 12 volts on it. The LEDs just push through holes. Note the polarity of the LEDs, the flat side

should go to ground. You may want to use some silicon RTV or glue to help hold in the LEDs.

Use the stand offs to mount the PC board in the box. Use the six mounting holes provided on the PC

board. If you are worried about RF getting into the system, you may want to connect an additional ground wire

from one of the mounting bolts to the chassis.

Once everything is mounted and wired, apply power again to make sure everything is still working.

Press the menu button and scroll through the LCD displays to verify the user interface is working.

Menu Functions:

This section will provide an overview of each menu and an explanation of the data presented on the LCD

module.

Current Voted:

The Current Voted menu displays which site is currently selected by the voter. The LCD will show only

one of the eight numbers in its position when selected (site one is in position one, site two is in position two,

ect.). On power up, site one will be chosen for the default. The display is updated when a new site is chosen as

the current voted. A site can not be selected as the current voted site if it has been disabled by either hardware

or software.

There are no user inputs for this menu.

Current Voted

Current CORs:

The Current COR shows which sites have active CORs. The LCD will show all site numbers in their

position when active. The LCD will update the display in real time. That is, if the COR for site one becomes

active, the display will show site one. If the COR becomes inactive, the display will immediately (within 50

mSec.) remove site one. A site will not be shown if it has been disabled by either hardware or software. The

display is updated when any COR input has changed.

There are no user inputs for this menu.

1 2

Current CORs

Channel S/N:

The Channel S/N menu will display the signal to noise ratio of the selected channel. There are two modes

of displaying the S/N ratio. The first is the internal number (0 to 255) used to represent the S/N ratio of each

channel (a higher number represents a higher signal). The second is a bar graph that approximates an “S-

meter” reading according to the S/N ratio. The select switch can be used in either mode to cycle through each

site. The data switch is used to toggle between number and bar graph mode.

The mode is not stored in Serial EEPROM and defaults to number mode on power up. The display is

updated every second for either mode.

Note: The Channel signal to noise ratio display can produce false readings if the input modulation

exceeds about 4 kHz bandwidth. If you are using the Channel S/N ratio for comparisons, take the reading with

no modulation.

Value = 255

Signal / Noise

or Value = xxxxxxxxxx

Signal / Noise

Hits per Chan:

The Hits per Chan menu shows the number of times a channel has been voted out of the last 100 COR

cycles. A COR cycle is the time from when any site becomes active to the time no sites are active. The hits for a

site is incremented if that site has been selected the most during a COR cycle (a site can be temporarily voted

during a COR cycle, but the hits for that site will not be incremented unless it has been voted the most during

that COR cycle).

The maximum number of hits on any channel is 100. Sites that are not selected at the end of a COR cycle

are decremented by one. For example, if the current hits are: site one - 57, site two - 28, site three - 12, and

site two is voted for the next COR cycle, the result is: site one - 56, site two - 29, site three - 11.

The Sel switch is used to cycle through each site. The LCD will display the channel number and the

number of hits.

The Hits per Channel is not stored in Serial EEPROM and all channels default to zero hits on power up.

Chan 01 Hits 64

Hits per Chan

Most Active:

The Most Active menu keep tracks of the hits per channel for each channel and displays the site with the

most votes out of the last 100 CORs. An internal count is kept on each site for the number of times it has been

voted. The site that has the most votes in the last 100 COR cycles is chose. If more than one site has the most

votes, the first site with the most counts encountered by the software will be chosen.

Sites that are disabled are not eligible to be selected as the Most Active site.

There are no user inputs for this menu.

Most Active

Least Active:

The Least Active menu is similar to the Most Active, except it keeps track of the site with the least

number of hits. If more than one site has the least COR counts, the first site with the least number of hits

encountered by the software will be chosen.

Sites that are disabled are not eligible to be selected as the Least Active site.

There are no user inputs for this menu.

Least Active

Hysteresis:

The Hysteresis menu display the currently selected hysteresis level (0 to 8). The hysteresis level is

the amount of signal to noise ratio improvement needed over the currently voted site before a new site will be

voted. The lower the hysteresis level selected, the smaller the amount noise improvement needed for a new

selection. Some amount of hysteresis should be used with all systems. Not enough hysteresis will result in

constant switching that may sound annoying. Too much hysteresis may result in large, noticeable changes in

audio when switching from noisy to quite site (or vice versa). A typical value used may be between 3 and 6.

In the RVS-8, the signal to noise ratio for each channel is represented internally by a number that has

a value between 0 and 255, with a higher number meaning higher signal (better signal/noise ratio). This

number can be viewed with the Channel S/N menu.

Each step of the hysteresis level is equal to 6 counts of the internal number. A hysteresis value of 5

means that a new signal must be 30 counts (5 times 6) higher than the currently voted signal before it will

become the newly voted channel.

The Sel or Data switch can be used to cycle the Hysteresis through the selections. When the selection

reaches 8, the next selection is 0. The Hysteresis data is stored in serial EEPROM.

Note: The 0 selection is recommended for testing purposes only. Since the software can update at 30

times per second, the 0 selection will allow sites to switch at that same rate and an audible 30 Hz buzz can

sometimes be heard.

Value = 4

Hysteresis

Disabled Chans:

The Disabled Channels menu show which channels are currently disabled. There are two ways to disable

a channel, by hardware or software. To disable the channels by software, press the Menu switch until

“Disabled Channels” is displayed on line two of the LCD module. Then press the Select switch until the desired

channel has the cursor, then press the Data switch to toggle between on or off. If the number is showing on the

display, the channel is disabled. If the number is not showing, it is not disabled by software or hardware.

To disable channels by hardware, an external connection must be made to the RVS-8 via J3. Depending

on how the Disable Active State is programmed for each channel, the voltage on each corresponding pin

determines if the channel is disabled or not (see menu section on Dis Active State).

The two disable systems are “ORed” together. That means that if the software “or” the hardware has a

channel disabled, the RVS-8 will disable that channel. Note that if the hardware has a channel disabled, the

software can not enable that channel. The reverse is also true, if the software has a channel disabled, the

hardware can not enable that channel. Pay close attention to this if you plan on having your repeater controller

handle site disabling.

The software disable data is stored in Serial EEPROM. Each time data is changed on the Disabled Chan

menu, data is written into the EEPROM. This data is non-volatile. If power is removed, the data will stay intact.

Data that has been programmed into the EEPROM is read into the Voter upon power up.

3 4 5 6 7 8

Disabled Chans

Dis Active State:

Each DIS (disable) input is programmable to be active high or active low. Active Hi means the external

control will produce a positive going voltage (6.5 to 20 volts) when the channel is to be disabled and a low

going voltage (0.0 to 4.5 volts) when the channel is to enabled. Active Lo means that your controller (or other

disabling device) will provide a low going voltage (0.0 to 4.5 volts) when the channel is to be disabled and a

high going voltage (6.5 to 20 volts) when the channel is to be enabled.

The DIS Active State menu shows the current selections for each external disable input. The Sel switch

is used to cycle through each input. The LCD will display the channel number and if the DIS is active Hi or Lo.

The Data switch is used to toggle the active state between Hi and Lo.

The DIS Active State data is stored in Serial EEPROM.

Chan 1 Active Hi

Dis Active State

COR Active State:

Each COR input is programmable to be active high or active low. Active Hi means that your receiver (or

link receiver) will produce a positive going voltage (6.5 to 20 volts) when the squelch is open (receiving a

signal) and a low going voltage (0.0 to 4.5 volts) when the squelch is closed (no signal). Active Lo means that

your receiver will provide a low going voltage (0.0 to 4.5 volts) when the squelch is open and a high going

voltage (6.5 to 20 volts) when the squelch is closed.

The COR Active State menu shows the current selections for each COR input. The Sel switch is used to

cycle through each site. The LCD will display the channel number and if the COR is active Hi or Lo. The Data

switch is used to toggle the active state between Hi and Lo.

The COR Active State data is stored in Serial EEPROM.

Chan 2 Active Lo

COR Active State

Other Inputs and Outputs:

Power Input: +12 volt power is supplied to the RVS-8 through J1. The actual voltage can be between +11 and

+15 and should be regulated. Total current consumption is less than 300 mA. If voltage drops below 11 volts,

the voter will still function, but the relay may not energize.

Audio / COR Output: J2 provides the audio and COR output. The audio output also has a separate ground

connection. The output adjustment for audio on J2 is provided by R125.

The COR output is supplied through relay K1 and J2. The relay can handle up to 5 amps at 250 volts.

The mechanical service life of the relay is 10 million operations (about 2500 operations per day for 10

years). The relay is a single pole, double throw type that can be configured for a normally open or normally

closed configuration. All switch contacts are floating with respect to the PC board (not tied to +12 or ground)

to allow for use with other than 12 volt systems.

User Interface: The User Interface (J7) provides connections to the front panel LEDs and pushbutton switches.

Refer to the diagrams near the end of the manual for specific pin connections.

Output Selection: The Output Selection header (J6) provides the user with an output that follows which site is

currently selected. The output pin (1 through 8) for the corresponding voted channel (1 through 8) goes to

+12 volts. All other channels will float to zero volts.

The software provides a special counting function that keeps track of the voted sites during a COR cycle.

Just before the COR cycle ends (about 1 mSec) the output selection will switch to the site that was voted most

during the cycle. This provides the user an opportunity to connect the output selection header to a controller

that will sense the selected site and take action (possibly change the tail beep or make a voice announcement).

Without this sensing software, the voter would constantly select the site with the longest tail squelch when the

COR cycle ends (not desireable).

The Selected / Continuous jumper JP1 changes the output to either continuously follow the voted

channel or only provide an output when a COR is active. In most cases, the jumper will be in the Continuous

position.

Pin 9 provides a ground and pin 10 provides +12 through a 1K resistor. These signals are provided in

case the Output Selection or other back panel connections need to be tied high or low for the equipment it is

connected to. The +12 pin is limited to 10mA.

Installation and Alignment: After the unit is in its case and properly turns on, you can run some audio

through a few of the channels to see how it operates. The alignment is pretty much the same as described in the

QST article. A voltmeter (as a minimum) can be used, but you may want to use an audio signal generator and an

oscilloscope for the audio path checks.

While on the bench, set up each channel to match your COR and Disable Active State. Also set all controls

in the center position. This will ensure that at least something gets through the audio circuits and something is

seen on the LCD module.

Only a few simple adjustments are needed to calibrate the input buffers, signal to noise converters and

the TX audio output. If on the test bench, the items needed for alignment are a receiver and a DC voltmeter. If at

the repeater site, only a voltmeter is needed since the receivers are already there. Variable resistors R17-24

control the amplitude of the audio for the input buffer of each input. Moving the control clockwise increases the

signal. It is important to match this as close as possible first to keep from having to compensate for differences

in the noise adjustments. Variable resistors R41-48 control the amplitude of the noise seen by the

microprocessor for each channel. Moving these controls clockwise increases the amount of noise. Variable

resistor R125 is the Audio output adjustment. This is the overall audio adjust that that will go to your

transmitter or controller. R136 is the contrast pot for the LCD module. It should initially be set in the center

position, then adjust for best contrast.

When calibrating the channels, you may want to disable all channels except the one you are working on.

This will prevent any channel from accidentally being selected while calibrating.

Ideally, you would transmit (over the air) different audio tones to all remote receiver and calibrate the

link receivers to have identical signals (in amplitude and frequency content) going to the voter. In the real

world, this may not be possible. Differences in radio equipment may change the audio response for each site.

The calibration procedure described here will give you good performance while maintaining a minimum

amount of time and test equipment required.

First, transmit a 1000 Hz tone at 2.5 KHz deviation to your link receiver. Be sure the link receiver

has a full quieting signal. A touch-tone signal from your handheld radio will work if you don’t have a tone

generator to connect to your transmitter. Adjust the receiver’s volume control and the Audio pot to read 2.0

volts AC on the meter at the audio test point for the channel. The audio test points are next to each

corresponding pot for that channel (they are marked AUD1, AUD2, ect). Check the Silk Screen layout sheet for

help locating these.

Next, with the squelch open and no RF signal on the receiver, adjust the noise test point to read 3.5

volts DC. The noise test points are located between C41-48 and RS-1 and are marked A/D1, A/D2, ect. Repeat

the audio and noise adjustments for the other seven channels.

Once at the repeater site, the adjustments should be close, but you may have to readjust to compensate

for receiver differences. You may want to temporarily connect toggle switches to the disable lines and set the

hysteresis to zero so you can quickly switch back and forth between sites to check for any audible differences

in audio.

Normally, a repeater system should use identical remote receivers and link equipment. This would

ensure that the audio characteristics are nearly the same for each site. If different equipment is used, it may

be necessary to place audio shaping components (such as a 1K resistor in series and .01 uf capacitor to ground

to filter out higher frequencies) in the audio lines to properly match the different audio characteristics.

Performance:

The performance from the RVS-8 is excellent. As the QST article stated, when the system is set up and

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