Jan 2007

Built DEMI  9ULNA 3456 preamp. Noise figure 0.6dB

Mar 2007

Scaled VE4MA superfeed from 1296MHz to 3456MHz using 2.5" tube. Dimensions.  Found pair of Vicor DC to DC converters that will convert 48V to 12V at 25A that can power the Toshiba Amp at the feedpoint.

May 2007

Finished the VE4MA superfeed. Reboxed the tropo 1994 built DB6NT 3456/144MHz transverter in smaller box . Built separate receive converter for 3400/144MHz with  W5LUA atf36077 preamp, collins surplus filter, connectorised mixer and a g4ddk009 local oscillator with 101.75MHz crystal.. Gives 0.6dB nf with 19dB of gain. It is possible to retune either unit to either band, takes 30 minutes

3400 Rx converter on left 3456 DB6NT Xverter on right

June 2007

Planned to participate in 3G eme activity event. June 16 hooked up equipment in pouring rain. Mounted 50w PA,  3400/144 xverter and 48v to 12v psu at feedpoint. Heard G4NNS on sked but he didnt hear me. Heard W5LUA on sked, weaker than G4NNS he may have heard me. Not too happy with preamp producing more noise from antenna than 50 ohm. Suspected oscillating preamp, so swapped out preamp which solved problem. Investigated amp. Only conclusion was that pa wasnt keying thereby producing no power.  No more skeds so took equipment off dish to retune xverter to 3456MHz

Overnight much rain. Put PA back on dish. Shortly after this had very local lightening strike. Completely took out PA. Luckily Preamp and Xverter not on dish so survived. Looked for alternate PA. Found RW89 TWT which gave 15W but couldnt be put on dish. Time for the dog kennel again. Unable to do anything for 2 hours due to torrential rain so investigated the 900MHz EME 3CX400U7 PA.  Left just preamp on dish. Put 3456MHz xverter, TWT, 24V PSU in kennel. QRV Just in time for VE4MA sked, started downpour again, nil heard either way.

Feedpoint equipment (xverter removed)               Kennel contents                    

Lessons learnt. Dont put gear at feedpoint, PA more protected and changing bands much easier. Beware of DC to DC converters.

To avoid having to retune the xverter between the two bands I decided I had enough spare parts to convert the receive converter into a transverter.By putting an sma relay on the output of the filter and feeding this into an ERA1 + ERA3 amplifier 13dBm could be produced, more than enough to drive the PA.It was also decided to use the original tropo PSU which had worked reliably for many years and accept the cable loss to the feed.  Replacement PA obtained and installed. Gives 45W on 3456MHz and 41W on 3400MHz with 7dBm of drive.

3400MHz Transverter                                                            Feed on dish with Preamp                              The 9cm kennel (2 xverters, PA, PSU)

July 2007

July 8 Worked G3LTF #1 on 3400MHz sked. PA worked fine for whole period. Only issue was pulses appearing from actuator without moving dish which made tracking difficult. Fortunately moon was visible so optical tracking employed.. LOT of water subsequently discovered in one of the connectors (who said Texas is dry?) 

July 14 qrv for 2nd 9cm activity period. Heard VK3NX (6dBN) on sked but he couldt hear me. July 15 Heard W5LUA(7dBn) and VE4MA (8dBn) on sked but they couldnt detect me. On sked with G4NNS we could detect each other on spectran but not loud enough for QSO. Condx worse than June 16. CWNR N9JIM at Jamesburg dish. As the Amp was being monitored for output and return loss, the issue must have been polarisation. Must check it out. Just as I thought wasnt going to work anyone worked LX1DB #2 on sked, just before he lost the moon. 

Mar 2008

Built new GPS locked 3400/144MHz transverter. This uses the G4HUP 101.75MHz DFS, G4DDK009 3G multiplier, packaged sma mixer, atf36077 2 stage W5LUA preamp and an ERA1+ERA6 transmit amplifier (20mW). Also fitted an onboard 10MHz oscillator to allow independant operation. Measured  noise figure 0.75dB/17db gain 

Apr 2008

After doing first day of the Dubus contest on 13cm I replaced the 13cm gear with the 9cm equipment, just in time for VK window. I detected VK3NX but not loud enough to work. On april 16 worked W5LUA #3 then OK1CA #4. Heard OK1KIR but he couldnt hear me. Also heard G3LTF weakly. Also worked W5LUA on JT65C 

May 2008

After seeing good published noise figures (0.48dB) for the DJ9BV 9cm preamp I decided to build one. I achieved the quoted gain, but the best noise figure I got was 0.63dB, which was slightly worse than my DEMI preamp.

Jun 2008

Put the 9cm feed on the dish in preparation for the activity weekend

Initial QSOS: 

CW

Also heard but not worked: G4NNS, OK1KIR, VK3NX, N9JIM

JT65C

GREEN = QSL RECEIVED

YELLOW = QSL SENT

Current Equipment: 

RX: DEMI preamp (0.6dB NF) mounted on feed via isolation relay.

Transverter:  3400MHz: Homebrew.  GPS locked. W5LUA ATF36077 RF, Collins Surplus Filter. SMA WJ 3G mixer, ERA1+ERA6 PA, G4DDK IF PIN switch, G4HUP 101.75MHz DFS locked to 10MHz GPS. G4DDK009 3G multiplier. 0.75dB/16.5dB. 13dbm out 

Transverter 3456MHz:  Homebrew.  W5LUA ATF36077 RF, Collins Surplus Filter. surplus SMA 3G mixer, ERA1+ERA6 PA, G4DDK IF PIN switch, G4DDK009 3312MHz multiplier. 0.7dB/16dB. 13dbm out

PA: Toshiba  PA. Output: 3456MHz 45W 3400MHz 41W

IF: FT847 on 144MHz

ANTENNA: 10' C band TVRO dish. F/D = 0.4.

This page last updated Jun 2 2008