Another work weekend at the station

Juha, OH6XX and I spent 4 days at the station to make some changes with the antennas. Some time ago we bought a 20-15-10 meter triplexer with HP BPF’s from Ranko, 4O3A. To make the antenna switching more simple, we decided to go monobanders with the EU tower.

Last Thursday we took down the EU tribander stack and started to make 4 el OWA yagis for 20, 15 and 10. Kari, OH5LF came to make some modifications to the AC distribution network and the grounding of the station.

New yagis were completed on Friday and lifting up to the tower was scheduled for Saturday. Peter, OH5NQ and Kimmo, OH5KS came to help and the antennas were up in the tower in less than 2 hours.

20 meter yagi is based on G0KSC desing with re-modelled element tapering. 15 and 10 yagis were replicated based on 20 meter data.

On Sunday we ran a 135 meter hardline to the EU tower to complete the assembly. On 40 we have a 1/2 inch cable, on 20 a 5/8 and on 15 and 10 meters a 7/8 inch hardline.

Next time we will add some stackmatches, triplexer, BPF’s and 50 ohm switchable dummy loads together with 4O3A SAC X controllers to complete new antenna switching system.

Until the next time

73, Timo OG9X

Another work weekend at OH5Z

We arrived the station on Friday evening and started to make a new
operating table for multiplier stations. We made a big shelf for the linears
and displays.
Next step was to repair the antenna switching. We had a problem with
160 and 80 meter antennas. Since it was getting very late we decided
to get some sleep and continue next morning.

Kari OH5LF and Kimmo OH5KS came on Saturday morning to fix the rotator
of the big 62 meter tower. The tower rotates OK, but the EA4TX control
box is burned and has to be replaced. Fortunately we have a possibility to
rotate the tower with a remote switch.

Juha OH6XX and I connected high band EU antenna back in business so
that we have 3 directions on 40 – 10 meters.

In the afternoon we replaced the broken coaxial for 40 meter stack.

After the sunset we continued with antenna switching. Finally the
problem was found and we got it operational again.

In the evening we participated The Polar Battle, Scandinavian Activity
Contest for a few hours with about 550 qsoa logged.

Now we are ready for CQ WW SSB contest. We will operate as a M/S
with 6 operators.

73, Timo OG9X

Repair weekend at OH5Z



Hi all

A week ago Juha OH6XX and me went to the station on Friday evening to make repairs after the thunder storm. Mikko OH6HZH joined us and as it was CQ WW RTTY contest weekend his intention was to work the contest part time.

We assembled the fixed stack matches for 40-10 meters and they seemed to work OK. We still have some problems with antenna switching and we could not route antennas for 80 and 15 to the station. That we have to look again next weekend.

Kari OH5LF came on Saturday to change the chain for 62 meter tower just to find out that the motor was burned and there was also something wrong with the gear. The azimuth indication potentiometer was also burned. He will come back next weekend to repair the rotating system. We also noticed that the EA4TX rotator control was not working. There were 2 burned fuses and it seems that the -12 V power supply was damaged.

Tried also repair the semi-automatic amplifier for 160-10 m. We thought the problem was with a time-delay chip which was replaced but could not get it working with automatic band switching. Have to look that again next weekend. Fortunately we can use it as a manual amplifier.

We made new phasing lines for 20-10 meter EU stack and replaced them. While checking the SWR of the stack we figured that the stack match was broken. OK, one more broken box to the to do list.

We took a walk up on the hill to check the beverages and found NA beverage being broken in 3 places. As we have very limited time to make repairs at the station it seems that we have to work CQ WW SSB contest without RX-antennas.


We will update after next weekend

73, Timo OG9X

Station automation

It all started in 2007 when we started think about making some things easier during the contests. One of the first ones that came to mind was automatic antenna switching. Having had Yaesu radios all the time at OH5Z made designing the antenna switching system a bit easier with the BCD data out from the back of the FT-1000MP. The main principal at the time was to be able to share automatically as many antennas as possible between four operating positions we had at the time. I searched the internet for commercial solutions but either they weren’t suitable or they were out of the budget. I decided to build the system by myself. I contacted Mike SM2WMV (SJ2W) with my ideas and he made a dozen PCB’s for us. After ordering a lot of relays, boxes, connectors and a lot of other stuff I started building the system.

The original antenna switching system consisted  of 6pcs 2×1’s, 2pcs 6×2’s and one 6×1. I also built a pair of stack matches. We can share all the antennas from 40-160m between all the stations with lockout system. On 10-20m bands we can’t share the big stack of four tribanders anywhere else than to RUN1 position. We have this limitation as they are all fed with one feedline and we are not using triplexer with them. All the other 10-20m antennas were originally shared between the three multiplier stations. Before CQ WPX 2014 SSB we added four more boxes, 3pcs 2×1 and 6×1 which now allows us to have three directions on RUN1 position on 10-40m bands.

During all of these years we have worked almost 90000 QSO’s and we have lost maybe 2-3 relays in total. That proves that Mike’s PCB designs are working great. We have had some RFI problems with relays clacking when shouldn’t have but the reason has been quite often on poor RFI protection on the band decoder end or some cable acting as antenna near the boxes.



73, Juha OH6XX