Repeater news

Locator: JO02KS
Location: Fakenham, Norfolk
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g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Repeater news

Post by g4wvu » Thu Aug 15, 2013 8:59 pm

Digital receiver 437MHz DVB-S, installed May 2013.
Fortec Star 4000 mk2, upconverter SUP2400, PGA103+ preamp , 7 pole AFL filter, fed by 25m LDF 450A heliax. Antenna is a "Big Wheel" at 23m.

FM tx : Wood & Douglas TVT1250 , Mitsubishi brick @12w output , 3 pole RF filter.

FM rx: frequency 1278 Mhz, Modified Commtech 23cm (RF: commtech, video clamping etc. bespoke) Filter-5 pole interdigital,

Aerials : omni's Alford slots + 4 DTMF switchable sectors.

Logic : Cropredy video generator for S.meter & testcard. IBM PC for info, teletext -DTMF status.
Bespoke CMOS control logic.

DVB-S transmitter under construction, to use kindly donated NDS broadcast kit + upmixer & new RF PA chain (to be share with FM tx exciter as the existing RF brick is not linear eough for DVB-S)

May use Antennair dual channel DVB-S board set depending on finances & group preferences.

Mark G4WVU 15/08/2013
Last edited by g4wvu on Sat Dec 07, 2013 10:37 pm, edited 1 time in total.

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Sat Aug 24, 2013 9:45 pm

437 mhz input DVB-S PIDS reset to general standard :

Video : HEX 100 / 256
Audio : HEX 101 / 257
PMT : HEX FFF / 4095

The receiver (Fortec Star FS 4000 II ) will lock to any valid PIDS (within reason) but the signal has to be present for about 5 minutes before it will RE-STORE other PIDS as default. .....use above :-)

MPEG coder installed for DVB tx......just awaiting time to install the rest!
New RF amplifier / mixer, new 24 & 12v PSU's , DVB Modulator, TBC & FM/DVB tx switching timer

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Fri Dec 20, 2013 9:12 am

DVB-S transmitter installed December 2013:

Selected by DTMF "8" on main sound channels. (between 2000-2300 weekdays & 1600-2300 weekends)

TBC. :CYP, MPEG encoder Tandberg 5000, Modulator NDS 3000, Upmixer-high level balanced ring (164 > 1316mhz), new MOSFET PA shared with FM tx. 40w (cw) run at 10w (av.) - DVB & 20w - FM.

PSUs 26v & 13.5v 10A each - switchmode.

Mark G4WVU 20/12/2013

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Wed Jan 15, 2014 10:01 am

Digital transmit is now fully operational on request. Normal (and default) transmission on 1316MHz is FM. DVB-S is activated by DTMF 8 on main sound channel or SU16 (433.4) - confirmed by "8 DVB-S transmit" lighting up on status card in Flashing Yellow (normally steady green). There will be approximately a 1 minute delay for DVB equipment to "warm" & transmission will switch to DVB-S, SR4000 FEC3/4. Main sound is on Left (ch1) Other sound (talkback etc) will be on right (ch1) & Left(ch2) Right(ch2). Output can be returned to FM anytime by DTMF 9 but the DVB equipment will run until timeout : 1 hour after which mains is switched off to the DVB equipment and TX returns to FM (if not already set). This is to save about 250w of electricity usage !! DVB kit may be replaced with a DTX1 - if much demand is seen: unlikely for the present. ;)

73s Mark G4WVU

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Wed Apr 16, 2014 9:20 am

DVB-S RX input added to 23cm (1248mhz) :

2MS/s , PIDS V HEX 100, A HEX 101, PMT HEX FFF (as standard - same as 437 DVB input ) )

Symbol rate is at 2MS rather than 4MS to try & reduce radar QRM from 1253mhz.

Other iputs 10.315Ghz & 1248mhz FM.

73s
Mark G4WVU

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Fri May 30, 2014 7:40 am

29/05/2014 Noticed received signal level from repeater very low & intermittant. Investigated on site ; high & intermittent reflected power from TX alford slot apparent.
The Rx (main 23cm Rx omni is in same double Alford stack) is already on a temporary separate Alford, so I suspect a major 23cm stack rebuild will be required as it has been up for 24 years! Repeater is out of service until antenna repairs can be effected.

Mark G4WVU

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Sun Jun 01, 2014 9:42 pm

TX is running on the spare Alford - so back on air. Alford stack taken down for inspection.
23cm rx is defaulted to SE sector (as no 23cm omni available). All other 23cm sectors are normal.

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Tue Mar 24, 2015 10:11 am

23 cm (1248mhz) DVB-S receiver removed from service (Radar interference & little or no usage ).

A link receiver will be added shortly to relay GB3NV (3406mhz Norwich) on request of DTMF, or when active (CTCSS from NV)

Current RX's are (MHz)
1248 FM
437 DVB-S
10315 WBFM
433.4 NBFM (talkback relayed on 6.5 audio subcarrier.)

TX is 1316 WBFM or 1316 DVB-S (4MS/s)

Mark
G4WVU

g4wvu
Posts: 52
Joined: Sat Jun 22, 2013 10:42 am

Re: Repeater news

Post by g4wvu » Fri Dec 13, 2019 2:36 pm

DVB-S transmit facility removed (FM only) . This was deemed a waste of power & space - no usage! (users preferred the analogue output)

S-Meter is displaying 437 MHz signal level at input. Meter has approximate level in dBm on the display &
The 1249 metering has been dropped because of little or no usage of 1249Mhz input - due to massive Radar QRM ( other frequencies tested in 24cm to no avail).

437Mhz input has two aerials - Omni (Big wheel) & a Double quad facing approx NE.

10GHz input frequency changed to 10.425Ghz (Thanks Adrian G0FVF for maintenance of this input)

Relay of GB3NV operational ; receives off air (3406Mhz DVB-S) from NV & relays any activity on Nv.

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