MFJ MFJ-8708 User Manual
MFJ-8708
High performance Mini 70cm, frequency agile Video-Audio ATV Transmitter
I Onlyto be used by a licensed radio amateur I
70cmn Mini Video/Audio Transmitter
Overview: The MFJ-8708 is a high quality 4 channel PLL synthesized mini(3.5 oz.) ATV transmitter. The MFJ-8708 is capable of transmitting on 4
different 70 cm ATV frequencies. Three of the frequencies coincide with the cable TV channels 58, 59 and 60. An audio sub-carrier generator is built in. All that is required is an audio source to transmit sound. No
external tuning is required since the MFJ-8708 uses a PLL synthesizer. Up to 16 custom frequencies within the allocated 70
cm ATV band can be provided.
A internal video test signal and an audio 1 kHz tone is built in for quick alignment of a receiver.
Notice:
The MFJ-8708 is an Amateur Radio ATV transmitter. The transmitter can ONLY be operated by a Technician class or higher licensed Radio Amateur in the USA and for legal purposes per 47 CFR part 97 of the FCC Rules. 97.113 of the FCC Rules prohibits Amateur Radio frequencies to be used to further any business purpose whether profit or non-profit. With few exceptions per 97.111 all transmissions must be directed to at least one other licensed Radio Amateur. Amateur Radio is intended for personal or hobby non-commercial communications between licensed Radio Amateurs. With the exception of running less than I Watt for radio control purposes, Amateurs must identify with their call letters plainly seen in the video every 10 minutes for extended transmissions and at the end of every transmission per 97.119.
MFJ-8708 User Interface Frequency Select Dip switches
There are 4 dip switches located on the MFJ-8708 that provide frequency selection.
Dip Switch 1 |
2 |
3 |
4 |
|
0 |
0 |
0 |
1 |
426.25MHz Normal Operation |
0 |
0 |
1 |
0 |
427.25MHz Normal Operation (Cable CH58) |
0 |
1 |
0 |
0 |
434.00MHz Normal Operation (Cable CH59) |
1 |
0 |
0 |
0 |
439.25MHz Normal Operation (Cable CH60) |
1 |
1 |
1 |
0 |
Test signal on 426.25MHz |
1 |
1 |
0 |
1 |
Test signal on 427.25MHz (Cable CH58) |
1 |
0 |
1 |
1 |
Test signal on 433.25MHz (Cable CH59) |
0 |
1 |
1 |
1 |
Test signal on 439.25MHz (Cable CH60) |
All other combinations of dip switch settings will turn off the RF carrier! While the MFJ-8708 is capable of operating on a total of 16 different pre programmable frequencies, stock modelsonly provide the 4 standard USA AM ATV frequencies. If you are a foreign licensed ham and or have different band plans, MFJ Enterprises will be glad to provide you with a custom programmed MFJ-8708.Pleasenote that we will ONLY provide you with custom frequencies that are within allocated ATV ham bands.
Antenna out
A BNC female connector provides RF output at 50 ohms exact. Make sure that the antenna is properly matched to 50 Ohms. You should also use the lowest loss coax and shortest length to minimize loss. DO NOT OPERATE WITHOUT A LOAD!
DC Power In
Supply voltage is 9V. The Red power lead is Positive (+) and the Black lead is Negative (-). The MFJ-8708 draws about 250mA of current. If you plan to use 9V batteries it is best to use two to three 9V batteries in parallel. You may certainly use a regulated external power supply with the MFJ-8708.
Audio and Video Inputs
The MFJ-8708 accepts NTSC or PAL composite video at 1 V P-P. Audio is standard line level and a small potentiometer provides audio input level control.
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