Good news!

For those who enjoy Radio Contesting Sport, the WRTC – World Radio Team Championship may be considered the Olympics of Amateur Radio. Held in a 4 by 4 years period, this year´s WRTC was hosted in Germany.

One of our team partners, who was in WRTC 2018, bought, for a great deal, a full set of 4O3A HP filters. These filters were used by Ranko´s 4O3A Super Station in Montenegro and now they are lent to our PY0F project.

We decided to change the panel N female connectors to panel UHF female connectors – simply due to convenience on standarizing all the RF connectors in the shack.

The availability of these filters is a major breakthrough on our project!. We are already working on redefine the layout of the station to a HP contesting station – Ohhh yeahhh!!!   😀   }:)    \,,/

Here are some photos from the work in bench:

 

 

 

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‘Murphy’ attacks!

During the last days of September (just about 1 month to CQWW SSB 2018), one of our rotors stopped working – probably due to the strong winds season in late August. Instead of taking it down we decided to substitute this rotor (a oldHy-Gain Ham IV) by the rugged Hy-Gain T2X Tailtwister rotor. The problem was that the T2X have been sitting around for a long time off on the ground and needed some maintenance before getting in service again.

After some work, the T2X rotor is ready to be put up on the tower again and keep our plans going. The rotor will be sent to PY0F and hopefully in time for CQWW SSB.

 

Hands On!

During the last week of August, Renner PY7RP and Marenga PU0FDN performed some work for the final assembly of the Tower #2 and antennas. The antennas on this tower will be mainly used for S&P. It consists of a 2 el Yagi on 40m and a 10-15-20m KT34XA.

Day #1 – Assembly of the 2 elem 40m Yagi

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elements of the 2el 40m Yagi laying on the ground

My flight was scheduled to depart from Recife at noon local time. The flight duration is about 50 minutes from Recife. After arrival I met Marenga PU0FDN at FDN airport.

Marenga´s  QTH is located less than 1 km from the airport and his antennas may be seen yet from the highway (the smallest federal highway of Brazil – 7 km long) .

At 1800z we began the assembly of the 2 elem 40 Yagi. This antenna was checked during our last visit in August. All parts were there and was easy to assemble.

 

Day #2 – Assembly of the last tower section & rotor/bearing/mast

 

Day #3 – Getting the 2el Yagi on the top and began assembly of the KT34XA tribander

 

So far so good, the 2el 40m yagi showed good SWR < 1,5 from 7.000Khz ~ 7.200Khz. After getting it on the air we prepared the long runs for Cellflex 1/2″ cables for both yagis and began the assembly of the KT34XA.

Day #4 – Finalizing the KT34XA assembly and getting it on the air!

Besides the good performance of KT34XA, the assembly is really a hard work to do. There are a lot (>200) tiny parts to mount and it is really time-consuming.

 

During the assembly and yet on the ground, we checked the SWR curves and showed somehow high SWR – as if the ressonant frequency been shifted to the high part of the 10-15-20. We first thought this could be minimized when the antenna got up to the tower. Unfortunately, that did not happen.

We have less than 90 days to CQWW SSB Contest. We are planning to get the antenna down to the ground to re-check all the assembly and parts. Hopefully we will get it fixed until the contest.

Pre-Assembling begins…

During July 13 to 17th, Renner – PY7RP, had been at the station to arrange some pre-assembling works that are scheduled to happen in mid August – 2018. The works included:

1. Check of the material shipped to PY0F in the last months: A lot of materials have been sent to PY0F. 2 x KT34XA + 2 el 40m Yagi + Masts + Coax Cables + Coax Connectors + Tables + Chairs etc. All the assembling work is planned to happen in mid August. All materials well packed and kept in safe on the site.

2. Check of the new location of the towers: During the last months we decided (for a number of reasons) to relocate 2 towers of the actual 4 towers of the station. The aim here was to draw a new sketch with actual spacing between the towers. We hope this new layout of towers will permit us to improve our low bands performance.

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3. Check on the actual structural situation of Tower #3: As being located on an island, the station maintainace must be very carefull. The Tower #3 will be one of our main towers and will need some repairs. All the problems were identified and hopefully the maintainance work will be done till mid August.

4. Check of the 2nd 2 el Yagi for 40m: All the antennas and parts were checked before being sent to PY0F, the only one missing was the 40 meters yagi. Due to the maritime transportation schedule, there was not enough time to check it before the shipment. All parts are OK.

 

5. Check of available space for reception antennas towards NA direction: Although we are located in a middle Atlantic Ocean island, QRN is high – probably due to agressive weather conditions over the eletric power net of the island. QRN is high on 160 and 80. For that reason we decided to improve our reception with some dedicated RX antennas. We found that on NA direction we have around 700 feet (210 m) of space to deploy a beverage antenna.

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In the end, everything seems to be running smoothly and our plans are up and running for the CQWW contests later in October and November – 2018!.

73´s – Renner, PY0F/PY7RP

Let´s talk about ‘Filtering’!

One of the most important items in a Contest Station is the filtering solution. Due to the proximity of the antennas, bandpass filters should be highly considered – first due to high QRM between the stations and second to protect the radios front end.

There are a lot of options available in the market. They are basicaly divided in two categories: The High Power BPF Filters and Low Power BPF Filters.

The High Power BPF Filters, such as well known Ranko´s BPF (4O3A) were designed to be used just after the linear amplifier. In this configuration, all the high power signal passes through the filter. This is desirable to better attenuate the harmonics amplified by the linear amplifier.

Low Power BPF Filters, are placed between the rig and amplifier or the rig and antenna switch. They are cheaper than the High Power ones.

The bandpass filters are “monoband” devices i.e. they can be used only on the actual  radio´s selected band. That means, if the radio is on 20 meters band, the BPF placed after the radio should be a 14mhz BPF. Although this is simple to understand, many people get confused on how to use them. Just imagine them as a “part of the tuned radio”, if the radio is tuned to 28mhz, a 28mhz BPF filter will be used.

That being said, we can look forward on some brands and analyze some important factors while selecting a filtering solution. They main factors are: Insertion Loss and Attenuation Curves.

The Insertion Loss is a number that reflects the loss (in dB´s) due to the device inserted in the transmission line. Good BPF´s should not have a Insertion Loss bigger than 1dB (better 0.5 or below that).

The Attenuation or Response curves is a curve which represents the BPF´s attenuation (in dB´s) in response to the frequency variation.

In all cases, these characteristics may vary a lot mainly due to the filter design used. There are a great number of different filter designs: Butterworth Filters, Chebyshev Filters, Bessel Filters, Eliptic Filters etc. Each design vary its characteristics: bandwitdh, insertion loss, response curve, riple etc. More about filter design and topologies can be found on this link.

For the Amateur Radio enthusiasts, there are a good number of brands that manufacture these filters. For Low Power, they are: Dunestar, OM-Power, Hamation, Low Band Systems and VA6AM. For High Power, they are: 4O3A, VA6AM and Low Band Systems.

Since our station profile is set to be a Low Power Contest Station, than set our focus on the Low Power filters available in market. Some factors were quite importants on choosing the filters. Besides the technical factors some other factors as financial, transportation, acquisition logistics got to be important too.

During our research we compared the attenuation curves between the different brand LP filters. You can check it ou by bands here: 10m15m20m40m80m160m. All the numbers were taken from the manufacturer´s web site. You can download all the table data in Excel format here.

In terms of insertion loss, the Dunestar BPF600 claims about -0.5db average insertion loss across the BPF band. The Hamation filters did not provide I.L. numbers on their website. Here also the LBS filters seemed the better I.L. between them with best than -0.5db in all bands. As can be seen the Low Band Systems BPFs are the LP filters with greater adjacent band attenuation. The QST Maganize published a review on LBS filters in March – 2017. Click here to read it.

Besides the great numbers of the LBS BPFs, some other factors were important on the decision to purschase these filters. On July 10th we ordered a 6 pack monoband filters by LBS. Andrei, RA6LBS, was very kind and proposed to delivery the pack himself during the WRTC event in Germany. The brazilian WRTC competitior, Alex PY2SEX is going to pick it up with Andrei and ship them to Brazil – hopefully before CQWWs contests.

lbs logo  lbs filters set

 

Tower #2 Base Foundation

On May 2nd, we began the excavation of the Tower #2 Base Foundation. In reality, this will be the relocation of one of the towers of the site. This tower will be set exclusively to the “hunter” station. The foundation is 4′ x 4′ x 4′ and will be filled with 30MPa concrete and steal reinforcement.

The photos above show the position of the new tower in relation with the actual 60ft tower – Tower #1 – (in the background) which hold the A4S + XM240.

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The steel reinforcement and two new 2″ O.D. masts are still in Recife waiting for the boat transportation. We hope to dispatch them yet on the first week of May.

To make transportation easy, we decided to bent and cut the steal reinforcement yet in Recife.

 

… More informations to come …

CQWW CW 2017 Results!

Hello OM!

Today we had a very good news about our last year effort on CQWW CW. This was our first ever contest from the island and it has a very special value for us. Since that operation was arranged on the last 15 days prior to the contest and with very limited setup and operator team, we assume that as a very expressive result for all the team.

cqww cw 2017
#4 World Wide, #1 South America – M/S LP – CQWW CW 2017