Private Bag X06, Honeydew,
2040 South Africa

 

Sentech certificate
 

 

 

 

 


                                                                                                            Jaap Lourens

                                                                                                            Technical Investigation Officer

                                                                                                            Sentech NTC.

 

                                                                                                            Tel. ( 011 ) 471-4400

                                                                                                            Fax.( 011 ) 471-4758

                                                                                                           

                                                                                                            16/01/2003.

Mr. Ian Robberts:

ZS6 BTE

No. xx xxxxxx str. Randparkridge.

 

 

Dear Mr. Robberts:

 

On 15/01/2003, I conducted some tests while you operated your Ham station, with the purpose of determining if your equipment radiated any out- of band signals, harmonics or spurii, after receiving complaints from some of your neighbours.

 

The main aim of the tests  conducted was to see if any out of band signals was radiated in the VHF/ UHF TV band, ( ch 4-13, and ch 21 - 68, as well as the FM band, 88 -108 MHz. )

 

Detail of test procedure:

 

a)       A constant pulsed,  unmodulated carrier at maximum transmitter input at 400 W was set up.

b)       A broad- band monitor antenna antenna was placed at a distance of about 20 metres, at a mean height of 8 metres,  from the transmitting antennas, which were turned right into the test antenna for maximum effect.

c)       Test was made on each of the VHF/UHF Ham bands, e.g. 50 Mhz., 145 Mhz., and 433 Mhz. all at full legal power.

d)       The frequency spectrum, as well as reception on each channel was then examined.

 

Herewith my findings:

 

a)       Off- air measurements on the Brixton  TV transmissions show a good average level of  77 dBuV for all  VHF transmissions, and  75 dBuV for UHF transmissions in your area.

b)       I could not see any out-of -band emissions on any of the above mentioned TV or FM channels, while your equipment were used.

c)       Harmonic suppression of your equipment seems well below the -60 dB point.

d)       Antennas and equipment is standard, and used power- levels within spec. for Ham operation.

e)       Your installation is sound, grounding and feed lines adhere to specification.

f)         You operate your station within the regulation set by the Amateur Radio Service Regulations, and Radio Act.

g)       You are licensed under the call- sign ZS6 BTE.

h)       It seems quite clear that the complaints received from neigbours is due to shortcomings, or equiment malfunction on the viewer's side. On your own TV reception, I could notice no interference.

 

Thus: according to the Radio- Act, you cannot  now be prohibited to operate your equipment, and you would also have no obligation to any complainant. The owner of the TV receiving installation must ensure that his or her installation adhere to SABS specification, and would also be responsible for all costs to modify/ correct such installation.

 

Regards:

 

Jaap Lourens

Sentech.