|Fig 1 Kit
The Multichannel Multipoint Distribution Service (Wiki)
was/is a way of getting wireless cable TV or in some cases
internet. Cable modems (Wiki) or
was the classical way people got cable TV. These boxes
accepted the VHF and UHF frequencies (Wiki)
in the range of 55 to 1,000 MHz, that were available on the coax
cable and were specific to each CATV vendor.
I expect that MMDS downconverters output a range of frequencies
that are close to what the cable modems used as inputs, that way
a cable provider would provide and antenna instead of a coax
feed from thier head end (Wiki).
||Retro Television Network||H/V||126.8
||GlobeCast World TV||H/V||142
||NBC, Pentagon Channel||H/V
||PBS Satellite Services
KU Band LNBF
RF: 12.2 - 12.7 GHz
IF: 950 - 1450 MHz
LO: 11.25 GHz
Gain: 60 dB
NF: 0.5 dB
Ku Twin LNBF
RF: 11.7 - 12.2 GHz
IF: 950 - 1450 MHz
LO: 10.75 GHz
Gain: 60 dB
NF: 0.6 dB
Freq: 950 - 2400 MHz
IL: 3 dB
Pwr: 500 mA Max
|Chain Link Fence Post used
for Free To Air (FTA) satellite dish
Red device is a three way level used to plumb the post while the concrete was wet.
at the lower left is the top of a ground rod.
|Free To Air (FTA) Dish on
Short F-type cable installed getting ready for signal strength meter.
|Degree marks enhanced
Clamp Bolts to prevent movement in azimuth not yet installed.
|Factory mounting tubing and
|The cable shown plugged into
the PCI card is the IR remote sensor.
The red and green LED are marked READY and WORK.
The two type-F connectors are marked LNB IN and LNB OUT.
Mini CD-ROM not shown in photo. Has:
rDirect X 9
|It turns out that my desktop
computer after upgrading the power supply still has marginal
capacity so no new hardware will be added to it. Maybe
it's time to get another desktop computer?
|The receiver is a Traxis
It has the Easy Find system that should make pointing the dish easier.
Not shown but included is a remote, instruction booklet and set of cables.
|DMS International USA -
lots of FTA info
Twin Ku LNBF
RF Freq: 11.7 to 12.2 GHz
LO Freq: 10.75 GHz
IF Freq: 950 to 1450 MHz
NF: 0.2 dB
clamp size: 40mm
They now have the Spitfire 0.1 dB NF LNB p/n spitfire
and they have the DBS4000 Receiver
This LNB uses the DISEqC Digital Satellite Equipment Control and in addition has the Easy Find feature that blinks an LED on the LNB to indicate signal strength and that you are pointed to the correct satellite.
|Radio Shack 15-1218 Passive
3-way Splitter i.e. A, B C Switch
The idea is that you can select one of three RF sources to feed a TV set that does not already have it's own input selection capability. For example Off Air Antenna, Cable or VCR.
Don't know if this splitter works with DISEqC Digital Satellite Equipment Control in terms of DC paths or frequency response.
|Cables and hardware package
|Dish mount bracket
|40mm LNB support
|1 Meter circular dish.
The motor has a couple of type-F connectors, one to the receiver and one to the LNB.
On one side of the mounting bracket is a L attitude scale and on the other side an elevation angle scale, either will work.
For me at 39N the elevation angle is 90 - 39 =) 51 degrees.
The declination angle that needs to be set on the dish bracket is down 6.14 degrees. This is because the satellites are not at infinity but rather close to the Earth so instead of zero declination angle you need to look down a little.
The 4 bolts that hold the motor to it's bracket were missing. They are M8-1.25 x 20mm with associated flat and lock washers.
The mast U-bolts may be the same size.
These down-converters are combined with an antenna and are designed to be mounted at the top of a mast. They use 75 Ohm TV type coax both to supply DC power to the down-converter and the feed the RF output from the converter to a receiver or cable modem.
These were on eBay for under $20. Came new in the box.
These two units have the L.O. at 2278 MHz, but I've seen other units where the L.O. is at: 2398 MHz,
Both of the below units were made by VCJ Universal, LLC
I believe this LNA (Wiki)Down-converter was intended to be mounted in a parabolic antenna, so only has a feed antenna.
VCJ Universal LLC.
MMDS Down Converter
L.O. 2278 MHz
Gain: 32 dBs/n: 2011011280201 probably 2011, Jan 12 ...
An on line ad had this information:
MMDS Down Converter Specifications:
Input Frequency Range: 2,500 to 2,700MHz
Output Frequency: 222Mhz-408Mhz Channels = (408 - 222)/6 = 31
L.O. Frequency: 2278 L.O.
Stability: ≤±30kHz (-40 - +70°C)
Image Rejection: ≥50dB Note: This means there is an input filter to block the image before the mixer.
Noise Figure: 2.5dB
IF Rejection: ≥80dB
PCS Rejection: ≥100dB
WCS Rejection: ≥50dBc
Gain: 32dB(can changed)
L.O. Leakage RF-port: ≤-85dBm
L.O. Leakage IF-port: ≤-50dBm
L.O. Phase Noise: offset
Output P1dB: +14dBm (typ.)
Gain Flatness over entire range: ≤±1.5dB
Gain Flatness: ≤0.2dB/channel
IF Output Impedance: 75ohm
Input type: integrated dipole antenna
Operating Temperature: -40 - +70°C
purious in IF Band: ≤-100dBm
DC input Voltage: 12V - 24V - WARNING some of the DirecTV power inserters are 29V, which may be too much for these units.
Storage Temperature: -40 - +80°C
Relative Humidity: 0% - 95%
Fig 1 As taken from box before installing reflector
Fig 2 After installing reflector.
This is a combined high gain antenna, LNA and down-converter.
VCJ Universal LLC.
Input: 2500 - 2700 MHz
L.O. 22768 MHz
Gain: 32 dB
Fig 3 The gold disk is thin sheetmetal with a wire soldered at left side.
Power Inserter, DirectTV
DirectTV Model P121R3-16
Freq: 2 to 2,150 MHz
Insertion Loss: 1.5 dB typ
Input 120 V @ 0.6 A
Output: 21 V @ 1.2 A max
An alternative method, but will not be used since I found the above combined bias-T and power supply.
4290068 Microwave television system, Richard D. Bogner, Sep 15, 1981 - uses the disk-on-rod antenna.
Disc-on-rod end-fire microwave antenna, Richard D. Bogner, Oct 13, 1981 -
4356493 Disc-on-rod end-fire microwave antenna, Richard D. Bogner, Oct 26, 1982 -5202699 (aka: 5300941) Integrated MMDS antenna and down converter, Dale L. Hemmie, Marc D. Mills, Apr 13, 1993 - very similar to the VCJ-L281 for BBQ Grill antenna
5402138 (aka 5448255) Integrated MMDS/MDS antenna and dual band down converter, Paul W. Hulett, Dale L. Hemmie, Marc D. Mills, Conifer Corporation,
Mar 28, 1995 -
[an error occurred while processing this directive] page created 27 Mar 2010.