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G1MFG.com 23cm transmitter & receiver technical notes issue 4
G1MFG.com
Home of the cheapest ATV transmitters and receivers in Europe!
23cm transmitter and receiver technical notes
This document contains technical information to help you use your 23cm transmitter
and/or receiver. Latest technical information can be found at http://www.G1MFG.com.
Power supply
The transmitter and receiver require a supply of 12 to 18V DC, tip positive. Reverse
polarity will cause very serious damage. Do NOT use less than 12V.
The transmitter gives best output power at 13.8V or more.
The heatsinks on the receiver get very hot over 13.8V, and run coolest at 12V.
Video and audio connections
Video and audio connections (inputs on the Tx and outputs on the Rx) are as follows:
Yellow phono socket - composite video
White phono socket - audio for/from 6.0MHz subcarrier
Red phono socket - audio for/from 6.5MHz subcarrier
Pre-emphasis/de-emphasis
The transmitter and receiver do not include video pre/de-emphasis. Simple preemphasis and de-emphasis circuits, plus a lot of other information and modifications are
on the G1MFG.com website, or you can get the info rmation by sending a stamped selfaddressed large envelope marked "MODS" to the a ddress at the end of this document.
Setting up the 23cm transmitter
The pre-set pot on the board provides a video gain (=deviation) control. The input i mpedance is somewhere in the region of 220 ohms: if you need 75 ohm impedance then
solder an 82 ohm resistor across the video input socket.
Setting up the 23cm receiver
The yellow pre-set pot on the standard receiver is the video gain control, and you'll need
to set it for proper amplitude video output. The control is a bit fierce and it can be hard
to set it to the right value - if you change the pot for a 1k cermet trimmer then the control
range is a lot smoother. Receivers modified by G1MFG.com have a blue 1k trimmer and
are much tamer.
Special note for Gold receivers
The ‘Gold’ receiver is modified to improve the sensitivity and picture performance. The
‘10k resistor’ mod has the unwanted side-effect on some receivers of shifting the receive
frequencies slightly from those in the tuning charts shown here. The frequency offset is
constant across the band, so you may find you get best results by tuning (say) 2MHz
lower or higher than whatever frequency you want to receive.
There is a wire link on the underside of the Gold receiver PCB which reduces the received noise level. This also affects the colour subcarrier amplitude. Most monitors
we’ve tried work fine with the reduced level, but some refuse to display colour. If you
find this is a problem with your monitor, please remove the link and colour should be r estored (at the expense of slightly more noise).
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G1MFG.com 23cm transmitter & receiver technical notes issue 4 Page 2 of 4
23cm transmitter and receiver operating frequencies
The following tables show the DIP switch settings for both the transmitter and receiver.
Note that 0=off and 1=on, and SW1 is the switch farthest from the metal box.
Table 1 - Commonly used frequencies
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
SW 7
SW 8
Notes
1248.0 0 0 0 0 1 0 0 0 RT1-3 repeater input
1249.0 0 1 0 0 1 0 0 0 RT1-2 repeater input
1276.5 1 0 0 1 0 0 1 0 RT1-1 repeater input
1285.0 0 1 0 1 1 0 1 0 Simplex
1308.0 0 0 0 1 0 0 0 1 RT1-3 repeater output
1311.5 1 1 1 1 0 0 0 1 RT1-1 repeater output
1316.0 0 0 0 1 1 0 0 1 RT1-2 repeater output
Table 2 - Complete frequency listing for 23cm Tx and Rx
Please note that some of these frequencies will cause emissions outside the 23cm amateur allocation
(1240MHz to 1325MHz) because ATV is a wide-band transmission. Refer to the band plans for details.
As a rule of thumb, you should be OK if you don't transmit below 1248MHz or above 1316MHz, and you
keep the transmit deviation reasonably low (compatible with other amateur stations). Disclaimer: this is NOT
a guarantee that you will not transmit out of band; please use the normal means of checking your transmitted signal
bandwidth.
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1240.0 0 0 0 0 0 0 0 0
1240.5 1 0 0 0 0 0 0 0
1241.0 0 1 0 0 0 0 0 0
1241.5 1 1 0 0 0 0 0 0
1242.0 0 0 1 0 0 0 0 0
1242.5 1 0 1 0 0 0 0 0
1243.0 0 1 1 0 0 0 0 0
1243.5 1 1 1 0 0 0 0 0
1244.0 0 0 0 1 0 0 0 0
1244.5 1 0 0 1 0 0 0 0
1245.0 0 1 0 1 0 0 0 0
1245.5 1 1 0 1 0 0 0 0
1246.0 0 0 1 1 0 0 0 0
1246.5 1 0 1 1 0 0 0 0
1247.0 0 1 1 1 0 0 0 0
1247.5 1 1 1 1 0 0 0 0
1248.0 0 0 0 0 1 0 0 0
1248.5 1 0 0 0 1 0 0 0
1249.0 0 1 0 0 1 0 0 0
1249.5 1 1 0 0 1 0 0 0
1250.0 0 0 1 0 1 0 0 0
1250.5 1 0 1 0 1 0 0 0
1251.0 0 1 1 0 1 0 0 0
1251.5 1 1 1 0 1 0 0 0
1252.0 0 0 0 1 1 0 0 0
1252.5 1 0 0 1 1 0 0 0
1253.0 0 1 0 1 1 0 0 0
1253.5 1 1 0 1 1 0 0 0
SW 7
SW 8
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1254.0 0 0 1 1 1 0 0 0
1254.5 1 0 1 1 1 0 0 0
1255.0 0 1 1 1 1 0 0 0
1255.5 1 1 1 1 1 0 0 0
1256.0 0 0 0 0 0 1 0 0
1256.5 1 0 0 0 0 1 0 0
1257.0 0 1 0 0 0 1 0 0
1257.5 1 1 0 0 0 1 0 0
1258.0 0 0 1 0 0 1 0 0
1258.5 1 0 1 0 0 1 0 0
1259.0 0 1 1 0 0 1 0 0
1259.5 1 1 1 0 0 1 0 0
1260.0 0 0 0 1 0 1 0 0
1260.5 1 0 0 1 0 1 0 0
1261.0 0 1 0 1 0 1 0 0
1261.5 1 1 0 1 0 1 0 0
1262.0 0 0 1 1 0 1 0 0
1262.5 1 0 1 1 0 1 0 0
1263.0 0 1 1 1 0 1 0 0
1263.5 1 1 1 1 0 1 0 0
1264.0 0 0 0 0 1 1 0 0
1264.5 1 0 0 0 1 1 0 0
1265.0 0 1 0 0 1 1 0 0
1265.5 1 1 0 0 1 1 0 0
1266.0 0 0 1 0 1 1 0 0
1266.5 1 0 1 0 1 1 0 0
1267.0 0 1 1 0 1 1 0 0
1267.5 1 1 1 0 1 1 0 0
SW 7
SW 8
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G1MFG.com 23cm transmitter & receiver technical notes issue 4 Page 3 of 4
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1268.0 0 0 0 1 1 1 0 0
1268.5 1 0 0 1 1 1 0 0
1269.0 0 1 0 1 1 1 0 0
1269.5 1 1 0 1 1 1 0 0
1270.0 0 0 1 1 1 1 0 0
1270.5 1 0 1 1 1 1 0 0
1271.0 0 1 1 1 1 1 0 0
1271.5 1 1 1 1 1 1 0 0
1272.0 0 0 0 0 0 0 1 0
1272.5 1 0 0 0 0 0 1 0
1273.0 0 1 0 0 0 0 1 0
1273.5 1 1 0 0 0 0 1 0
1274.0 0 0 1 0 0 0 1 0
1274.5 1 0 1 0 0 0 1 0
1275.0 0 1 1 0 0 0 1 0
1275.5 1 1 1 0 0 0 1 0
1276.0 0 0 0 1 0 0 1 0
1276.5 1 0 0 1 0 0 1 0
1277.0 0 1 0 1 0 0 1 0
1277.5 1 1 0 1 0 0 1 0
1278.0 0 0 1 1 0 0 1 0
1278.5 1 0 1 1 0 0 1 0
1279.0 0 1 1 1 0 0 1 0
1279.5 1 1 1 1 0 0 1 0
1280.0 0 0 0 0 1 0 1 0
1280.5 1 0 0 0 1 0 1 0
1281.0 0 1 0 0 1 0 1 0
1281.5 1 1 0 0 1 0 1 0
1282.0 0 0 1 0 1 0 1 0
1282.5 1 0 1 0 1 0 1 0
1283.0 0 1 1 0 1 0 1 0
1283.5 1 1 1 0 1 0 1 0
1284.0 0 0 0 1 1 0 1 0
1284.5 1 0 0 1 1 0 1 0
1285.0 0 1 0 1 1 0 1 0
1285.5 1 1 0 1 1 0 1 0
1286.0 0 0 1 1 1 0 1 0
1286.5 1 0 1 1 1 0 1 0
1287.0 0 1 1 1 1 0 1 0
1287.5 1 1 1 1 1 0 1 0
1288.0 0 0 0 0 0 1 1 0
1288.5 1 0 0 0 0 1 1 0
1289.0 0 1 0 0 0 1 1 0
1289.5 1 1 0 0 0 1 1 0
1290.0 0 0 1 0 0 1 1 0
1290.5 1 0 1 0 0 1 1 0
1291.0 0 1 1 0 0 1 1 0
1291.5 1 1 1 0 0 1 1 0
1292.0 0 0 0 1 0 1 1 0
1292.5 1 0 0 1 0 1 1 0
1293.0 0 1 0 1 0 1 1 0
SW 7
SW 8
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1293.5 1 1 0 1 0 1 1 0
1294.0 0 0 1 1 0 1 1 0
1294.5 1 0 1 1 0 1 1 0
1295.0 0 1 1 1 0 1 1 0
1295.5 1 1 1 1 0 1 1 0
1296.0 0 0 0 0 1 1 1 0
1296.5 1 0 0 0 1 1 1 0
1297.0 0 1 0 0 1 1 1 0
1297.5 1 1 0 0 1 1 1 0
1298.0 0 0 1 0 1 1 1 0
1298.5 1 0 1 0 1 1 1 0
1299.0 0 1 1 0 1 1 1 0
1299.5 1 1 1 0 1 1 1 0
1300.0 0 0 0 1 1 1 1 0
1300.5 1 0 0 1 1 1 1 0
1301.0 0 1 0 1 1 1 1 0
1301.5 1 1 0 1 1 1 1 0
1302.0 0 0 1 1 1 1 1 0
1302.5 1 0 1 1 1 1 1 0
1303.0 0 1 1 1 1 1 1 0
1303.5 1 1 1 1 1 1 1 0
1304.0 0 0 0 0 0 0 0 1
1304.5 1 0 0 0 0 0 0 1
1305.0 0 1 0 0 0 0 0 1
1305.5 1 1 0 0 0 0 0 1
1306.0 0 0 1 0 0 0 0 1
1306.5 1 0 1 0 0 0 0 1
1307.0 0 1 1 0 0 0 0 1
1307.5 1 1 1 0 0 0 0 1
1308.0 0 0 0 1 0 0 0 1
1308.5 1 0 0 1 0 0 0 1
1309.0 0 1 0 1 0 0 0 1
1309.5 1 1 0 1 0 0 0 1
1310.0 0 0 1 1 0 0 0 1
1310.5 1 0 1 1 0 0 0 1
1311.0 0 1 1 1 0 0 0 1
1311.5 1 1 1 1 0 0 0 1
1312.0 0 0 0 0 1 0 0 1
1312.5 1 0 0 0 1 0 0 1
1313.0 0 1 0 0 1 0 0 1
1313.5 1 1 0 0 1 0 0 1
1314.0 0 0 1 0 1 0 0 1
1314.5 1 0 1 0 1 0 0 1
1315.0 0 1 1 0 1 0 0 1
1315.5 1 1 1 0 1 0 0 1
1316.0 0 0 0 1 1 0 0 1
1316.5 1 0 0 1 1 0 0 1
1317.0 0 1 0 1 1 0 0 1
1317.5 1 1 0 1 1 0 0 1
1318.0 0 0 1 1 1 0 0 1
1318.5 1 0 1 1 1 0 0 1
SW 7
SW 8
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G1MFG.com 23cm transmitter & receiver technical notes issue 4 Page 4 of 4
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1319.0 0 1 1 1 1 0 0 1
1319.5 1 1 1 1 1 0 0 1
1320.0 0 0 0 0 0 1 0 1
1320.5 1 0 0 0 0 1 0 1
1321.0 0 1 0 0 0 1 0 1
1321.5 1 1 0 0 0 1 0 1
1322.0 0 0 1 0 0 1 0 1
1322.5 1 0 1 0 0 1 0 1
1323.0 0 1 1 0 0 1 0 1
1323.5 1 1 1 0 0 1 0 1
1324.0 0 0 0 1 0 1 0 1
1324.5 1 0 0 1 0 1 0 1
1325.0 0 1 0 1 0 1 0 1
1325.5 1 1 0 1 0 1 0 1
1326.0 0 0 1 1 0 1 0 1
1326.5 1 0 1 1 0 1 0 1
1327.0 0 1 1 1 0 1 0 1
1327.5 1 1 1 1 0 1 0 1
1328.0 0 0 0 0 1 1 0 1
1328.5 1 0 0 0 1 1 0 1
1329.0 0 1 0 0 1 1 0 1
1329.5 1 1 0 0 1 1 0 1
1330.0 0 0 1 0 1 1 0 1
1330.5 1 0 1 0 1 1 0 1
1331.0 0 1 1 0 1 1 0 1
1331.5 1 1 1 0 1 1 0 1
1332.0 0 0 0 1 1 1 0 1
1332.5 1 0 0 1 1 1 0 1
1333.0 0 1 0 1 1 1 0 1
1333.5 1 1 0 1 1 1 0 1
1334.0 0 0 1 1 1 1 0 1
1334.5 1 0 1 1 1 1 0 1
1335.0 0 1 1 1 1 1 0 1
1335.5 1 1 1 1 1 1 0 1
1336.0 0 0 0 0 0 0 1 1
1336.5 1 0 0 0 0 0 1 1
1337.0 0 1 0 0 0 0 1 1
1337.5 1 1 0 0 0 0 1 1
1338.0 0 0 1 0 0 0 1 1
1338.5 1 0 1 0 0 0 1 1
1339.0 0 1 1 0 0 0 1 1
1339.5 1 1 1 0 0 0 1 1
1340.0 0 0 0 1 0 0 1 1
1340.5 1 0 0 1 0 0 1 1
1341.0 0 1 0 1 0 0 1 1
1341.5 1 1 0 1 0 0 1 1
1342.0 0 0 1 1 0 0 1 1
1342.5 1 0 1 1 0 0 1 1
1343.0 0 1 1 1 0 0 1 1
G1MFG.com: L'Eglise, Durley Street, Durley, Hampshire, SO32 2AA.
01489 860 318 (eves/weekends)
Website http://www.G1MFG.com; email [email protected]
SW 7
SW 8
Frequency
(MHz)
SW 1
SW 2
SW 3
SW 4
SW 5
SW 6
1343.5 1 1 1 1 0 0 1 1
1344.0 0 0 0 0 1 0 1 1
1344.5 1 0 0 0 1 0 1 1
1345.0 0 1 0 0 1 0 1 1
1345.5 1 1 0 0 1 0 1 1
1346.0 0 0 1 0 1 0 1 1
1346.5 1 0 1 0 1 0 1 1
1347.0 0 1 1 0 1 0 1 1
1347.5 1 1 1 0 1 0 1 1
1348.0 0 0 0 1 1 0 1 1
1348.5 1 0 0 1 1 0 1 1
1349.0 0 1 0 1 1 0 1 1
1349.5 1 1 0 1 1 0 1 1
1350.0 0 0 1 1 1 0 1 1
1350.5 1 0 1 1 1 0 1 1
1351.0 0 1 1 1 1 0 1 1
1351.5 1 1 1 1 1 0 1 1
1352.0 0 0 0 0 0 1 1 1
1352.5 1 0 0 0 0 1 1 1
1353.0 0 1 0 0 0 1 1 1
1353.5 1 1 0 0 0 1 1 1
1354.0 0 0 1 0 0 1 1 1
1354.5 1 0 1 0 0 1 1 1
1355.0 0 1 1 0 0 1 1 1
1355.5 1 1 1 0 0 1 1 1
1356.0 0 0 0 1 0 1 1 1
1356.5 1 0 0 1 0 1 1 1
1357.0 0 1 0 1 0 1 1 1
1357.5 1 1 0 1 0 1 1 1
1358.0 0 0 1 1 0 1 1 1
1358.5 1 0 1 1 0 1 1 1
1359.0 0 1 1 1 0 1 1 1
1359.5 1 1 1 1 0 1 1 1
1360.0 0 0 0 0 1 1 1 1
1360.5 1 0 0 0 1 1 1 1
1361.0 0 1 0 0 1 1 1 1
1361.5 1 1 0 0 1 1 1 1
1362.0 0 0 1 0 1 1 1 1
1362.5 1 0 1 0 1 1 1 1
1363.0 0 1 1 0 1 1 1 1
1363.5 1 1 1 0 1 1 1 1
1364.0 0 0 0 1 1 1 1 1
1364.5 1 0 0 1 1 1 1 1
1365.0 0 1 0 1 1 1 1 1
1365.5 1 1 0 1 1 1 1 1
1366.0 0 0 1 1 1 1 1 1
1366.5 1 0 1 1 1 1 1 1
1367.0 0 1 1 1 1 1 1 1
1367.5 1 1 1 1 1 1 1 1
SW 7
SW 8
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