2006 UK RTTY Contest Award

The award finally arrived on today. I need to wait more than two years for this nice colourful award issue by GM4FDM.

Russian DX Contest 2008

Over the weekend, participate in the Russian DX contest all band-phone.
I have been in this contest started from 2005 and have fun with it.
With the low solar activity, band condition was poor. My score not as good compare to last year.

TX5C

With a simple trap dipole,which is only two meters high on the roof, I was lucky to catch TX5C on 40M at 1428z on 9 March. It is very difficult becasue of JA wall. I need to call almost for an hour to get it, new one for me on 40M.

I hope to have them in the log on 20M and 17M. Watch and wait for good propagation ...

Palestine E4/OM2DX

The QSL card arrived yesterday.

Band condition was poor lately, only worked them on 20M.

Porsche and Jade with RED PACKETS

As promised, Martin and Anni gave Porsche and Jade the "RED PACKETS" for the year of RAT. They like it very much but Jade walk away when taking photos !

Six Meter SB-220 Rebuild

Steve, VR2XMQ gave me the SB-220 when the time he moved QTH. The amplifier was modified to six meter by one of the ham in the United States. However, the amplifier experienced with problem since it arrived. In the first instance, the HV meter was damaged in shipping and flash over when switch on, which finally proved one of the 3-500z have problem. The outlook of the amplifier was bad, most of the screws are rusted and internal wiring is in a mess, overall it is not a professional workmanship.
The amplifier was sit there for sometime and few weeks ago, I decided to re-build the amplifier and make it ready for cycle 24 for some DX in the magic band.
Here below are the major improvements:
1) repainted the power and filament transformer and inside chassis
2) replace most of the rusted screws
3) replaced all eight HV filter capacitors to 270uf 450V 105 degree C
4) replace the HV rectifier board completed with eight 1N4007, which used as the 5.1V bias zener diode
5) replace two panel meters
6) replace the load capacitor
7) add soft-start and soft-key
8) replace the burnt safety choke (8 mm Teflon rod with approx. 60 turn of SWG 22 wire.)
9) replace one 3-500z
10) refine the input SWR
11) tidy up all internal wiring

With AC mains supply at 207V, it gave out 900W with 100W drive. It can be more if AC voltage up a little bit. Now it is a 100 percent working amplifier and ready to go.

WPX Phone Contest 2007

Another achievement for WPX Phone contest 2007. I am very surprised to be no.1 in Asia for 21 MHz . I will participate in this year contest again, still not decide which band to go, may be 14 MHz?

Contest Award

Very happy received ARRL International DX contest Award 2007 on today.

Power-on delay PCB

I made a new power-on delay relay circuit (soft-start) PCB yesterday. The zener diode which create a high turn on voltage for the Darlington connected transistor pair. The delay is approx. 3 seconds using 47K resistor and 100 uF capacitor. Longer delays can be obtained with a large capacitor.

GI7B Six Meter Amplifier Project - Update 9

It is connected to a BIRD Dummy Load (Model 8401) and 43 Watt Meter and easy tune to approx. 700W output. End of the project. Look forward to hear you on the magic band.

GI7B Six Meter Amplifier Project - Update 8

First RF test and found the tune variable capacitor totally meshed out, then I removed few plates and measured the capacitance is in between 4.5 to 10 pF. The tank coil also cut one Turn, now is 3 turns. The load capacitor is half-meshed, just fine.

After that, test Starting with 5 W of drive from a TS-600, gave 85W on the output first time, which equal to about 12.3 db gain.

Increasing the drive up to 10W brought 150W output, equal to 12.07 db gain.

I stopped at this point because the 150W dummy load already very hot, will test later with a high power one.

I also installed the top cover with ventilation holes.

GI7B Six Meter Amplifier Project - Update 7

Last evening round up all connections and perform initial test at the input SWR. At firs, the SWR is quite high with 1:3 , modified the coil to 4 turn 13 mm dia. with good result at 1:1.2.

After that, connect plate voltage and measured the plate idle current at 80mA, which indicated it is correct.

Now the amplifier is ready to go for load test.

GI7B Six Meter Amplifier Project - Update 6

Logan (VR2XRW) gave me a 10mm ferrite rod for the filament choke, it is in place all together with the input tune, consists of two Arco variable capacitors and 15mm dia. coil.

The GI7B tubes are in place. They were supplied with the filament votlage for few hours.

Front Panel

Plate Voltage and Amperes meter installed on front panel, it fit well and look good.

The meter at right hand side showing 2050 V DC, scale need to calibrate later.

GI7B Six Meter Amplifier Project - Update 5

The high voltage supply was wired up.
AC 220V input to primary winding (240V) and secondary measured at 800V tapping is 730V. After rectifier and voltage doublers, measured at 2050V DC. It meets with the plate voltage of the GI7B.
The soft key and bias board PCB is mounted at the bottom, nearby the T/R relay.

Plate Choke

The plate choke is made from 50-turns, 22swg(purchased from UK), close wound on a 80mm length of 20mm PTFE rod(purchased from Apliu Street)

It is tapped hole in one end for support.

GI7B Six Meter Amplifier Project - Update 4

Last evening I have completed the high voltage board as well as placing the high voltage transformer into the chassis. The high volatge PORCELAIN insulator and safety resistor (47 ohm 50W) are also in place.

GI7B Six Meter Amplifier Project - Update 3

In the past couple of day, the six meter amplifier project moving very slow.

1) I have made the PCB Board Fabrication for High Voltage and Soft Start. This weekend, will go for the Software Key and Bias PCB.
2) I also drill two big holes for the front panel meter High Voltage and Plate Current meter. Although it is a tough work, which took me an hour to complete, it looks very nice.
3) I cut 80mm Telfon Rod of 20mm Diameter for the plate choke. SWG 22 wire expect arrive from UK within this week.
4) I bought one 12V 10A contact rating Omron relay from Apliu Street, which is for the T/R switching.

From the photo, you can see the soft start PCB mounted on the bottom of the chassis.

GI7B Six Meter Amplifier Project - Update 2

If is quite difficult to get small diameter of copper tubing. It needs to buy at least a roll of several meter of quantity. So I give up this kind of material. Looking around and thinking of using surplus short length of hard line cable, center conductor is 5mm diameter. Wound 4 turn, inner diameter 40mm.
Doorknob capacitor is 1000pf 15KV purchased from Mainland China.

GI7B Six Meter Amplifier Project - Update 1

Yesterday went to Canton road to cut the aluminum sheets for the front panel and partition for the chassis. Six pieces cost of $215. I also locate one winding transformer company and ask for the quote for a 1000VA transformer at a reasonable cost. Size is approx. 6”x6”x6” and delivery time is one week. I told the shop will prepare the specification and order next week. What a surprise that they have transformer oil (for my HN-31 Heathkit dummy load) in stock, which is very rare and difficult to find here.

The major component is ready and has tried to place them on the chassis and it looks fine.