2m/70cm Yagi

Some time ago I decided to get a new 2m antenna, one which would enable me to work more DX stations, in particular the ones in and around the United Kingdom. At this moment I'm using a small yagi which is vertically polarized directed towards one of the local Dutch 2m repeaters (PI3ZLB). The specifications for my new antenna were simple : 4 or 5 elements, at least 200W, robust and not too expensive of course. I did some research on the internet and this resulted in a dozen, ready to use, models. Great specifications indeed for all these models, but the prices unfortunately shocked me a bit : they were far too expensive. After having a few chats with PA3GDS (Math), he advised me to look for a DK7ZB antenna kit. These kits are sold by various shops, but one of the shops in Germany turned out to be the cheapest one. And there is another thing to mention : I decided to order a dualband yagi 2m/70cm kit (4 elements for 2m, 5 elements for 70cm). Price tag : only 34,50 EURO's, a real bargain ! The antenna kit arrived within 3 days after making the payment. Thanks Math for this valuable lead !

2m 70cm yagi - design DK7ZB - 5   2m 70cm yagi - design DK7ZB - 6

The building process of the yagi has almost been completed. The only missing item now is the choke which is going to be fitted in the connection box.

2m 70cm yagi - design DK7ZB - 7   2m 70cm yagi - design DK7ZB - 8

On the left the (spoiled) choke : I accidently ruined the RG-188 (PTFE) teflon coax by damaging the shield/braid (I cut the outer insulation too deep) and therefore losing too much length of the coax for the needed 7 windings. There was a solution though getting the choke fixed by using standard RG-58 coax, but I decided not to use this alternative because of the 50 Watts power limitation versus approximately 250 Watts when using the teflon coax. For now I will have to wait for a new piece of RG-188 to arrive.

On the right the supplied mast clamp (optional) which can be used both vertically and horizontally. My setup probably will be a fixed one, horizontally polarized, bearing north west.

2m 70cm yagi - design DK7ZB - 2   2m 70cm yagi - design DK7ZB - 3

When I have completed the dual band yagi, it will replace my 3 elements HB9CV for 2m.

2m 70cm yagi - design DK7ZB - 10

February 11th 2012 : the choke is ready to be boxed now, 7 windings as described by DK7ZB

2m 70cm yagi - design DK7ZB - 9   2m 70cm yagi - design DK7ZB - 11

Construction of the pole for erecting the yagi in progress. The pole is made of pvc, 5cm in diameter. The antenna is bearing 292,5 degrees (west north west) towards the United Kingdom and Ireland.

2m 70cm yagi - design DK7ZB - 13

An impression of the 2m/70cm situation in the attic. 

2m 70cm yagi - design DK7ZB - 16   2m 70cm yagi - design DK7ZB - 15

The new 2m/70cm antenna is also the main motive for changing all the HF and VHF/UHF feeders and getting these into the shack more easily. All the current RG-58 is going to be replaced by Aircell-7 coax and high quality (=low loss) connectors. The Diamond CX210's (picture on the right) will be used for switching between the FD4, 2m vertical, 2m/70cm yagi (horizontal) and the future 4m/6m dipole/yagi.

2m 70cm yagi - new coax switch board - 17   Comet CAT-273 2m en 70cm tuner

The new switch board is ready now.              My new Comet CAT-273 tuner for 2m & 70cm will act together with the DK7ZB yagi.

2m 70cm yagi - design DK7ZB - 18   2m 70cm yagi - design DK7ZB - 19

The 2m/70cm yagi is now fully operational. A few contacts with the UK showed that the antenna is working great !

2m 70cm yagi - design DK7ZB - 20

A closer look at the connection box and attached Aircell-7 coax.

2m 70cm yagi - design DK7ZB - vertical

September 15th 2012 : the second 9 elements yagi is operational, this time vertically polarized. The antenna is bearing 25 degrees (north north east) and will be used mainly for the local QSO's. Building this antenna for the second time was a piece of cake.

 

The 2m/70cm antenna kit (design : DK7ZB) was provided via NuxCom in Germany (great quality and service from Nuxcom, so I can strongly recommend them to you).