Showing posts with label 8 element. Show all posts
Showing posts with label 8 element. Show all posts

Thursday 5 October 2017

New Driven Element

I've changed the driven element of my DK7ZB to the DG7YBN (K6STI) style. This has the advantage of a 50 ohm direct feed eleminating the need for the 50-28 Ohm DK7ZB match. I've had problems water proofing the old match and not been able to source decent 75 Ohm coax anyway.
VSWR is very low and as far as I'm able to tell there is no loss of gain. Proof of the pudding will be in the eating.  EME contest this weekend so if I can make a few contacts I'll be happy if not I might have to reinstall the old DE.
The DG7YBN driven element

Update 15th October 2017

First EME contact with the new driven element

And it seems to work

Revieved this nice comment from Hartmut 

 On 01/11/2017 23:07, Blogger Contact Form wrote:

Nice modification on the 2 m Yagi there!
A number of low impedance Yagi are suitable of having a bent driven
element replacing mathcing devices like a T-Match or parallel coaxes.
And this also works out in the NEC model.

Well done.
73 de DG7YBN



Here's a link to Hartmut's website
DG7YBN - Low Noise Yagis

Friday 23 December 2016

Successful EME contacts

Massive EME array?  8 element DK7ZB
 Success

After several weeks of trying I finally got lucky and had two QSOs via EME.  Below are several screen shots from the contacts. The only thing that was different this time was the antenna. I used my 8 element DK7ZB instead of the thirty year old 9 element Tonna.  The Tonna is showing signs of it's age and I'm wondering if the corrosion is affecting it's gain.

Equipment

Modified Kenwood TM255E (SI570 LO, IF tap)
Homebrew SDR tuned to TM255E IF
Homebrew 300 Watt amp (Freescale MRFE6VP6300 mosfet)
8 element DK7ZB  (gain 12 dBd)
Software;
WSJT-X v1.7.0-rc2
PowerSDR-IQ


So I'm pretty happy with that and looking forward to more contacts.

Transmitting RO
Completed QSO
The second contact was an answer to my CQ, pretty suprised I can say
Second contact
And a card