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Call Sign : 29-CT-024 Posts : 32 Times Thanked : 0 Join date : 2020-04-27 QTH or Location : Ireland/Germany Equipment Used : Team CB/FX mobile & 1.5m orbitor. Sirio HP 4000/Maas DP-27 & Grant 2 premium
Subject: MAAS DP-27 dipole antenna tuning Thu Jun 04, 2020 9:15 am
Hello all,
I just bought a Maas DP-27 dipole (Yes yes I know I could have made one etc etc but I had no materials and for the price of this and my time it was definitely easier and cheaper to buy this one). Anyway the quality of the dipole on first impressions is great, with stainless wire and connections and high quality plastic parts. Its a 1/2 wave at about 5m long
So I threw it up last night on my balcony (basically identical to the balcony in the pic from google images) I just left it resting on the timber face and swr'd it, the swr was sky high. I proceeded to shorten it and did get the swr to 1-1.5:1 but i had to shorten it a lot ! (I didn't cut it).
My question is, how much should I be shortening it at a time to make a difference ? It was pretty late and I wasn't giving it my absolute best, will be trying again tomorrow but would like some advice, Does it ideally need to be suspended and not lying on a surface ?
I would like to operate from 26.965 MHz - 27.855 MHz predominantly
Cheers & 73,
Mark
Northern Crusader Major contributor
Call Sign : M0GVZ / 26CT1760 Posts : 530 Times Thanked : 35 Join date : 2019-11-13 QTH or Location : IO94SA Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike Age : 53
You need to tune it for where it's going to be used so that'll probably mean putting it up and down a fair few times and it's times like this where an antenna analyser becomes worth the money because you can take a reading then adjust it a bit and see how many kHz that amount of adjustment gives you. You can't do this with a SWR meter nearly as well.
Where you had it it'll have been capacitively coupling to loads of stuff, including the house wiring, so will appear electrically longer. You'll find when you move it to where it's going to be installed you're likely to need to lengthen the elements so it was a good job you didn't cut.
MrFendt New Member
Call Sign : 29-CT-024 Posts : 32 Times Thanked : 0 Join date : 2020-04-27 QTH or Location : Ireland/Germany Equipment Used : Team CB/FX mobile & 1.5m orbitor. Sirio HP 4000/Maas DP-27 & Grant 2 premium
Subject: Re: MAAS DP-27 dipole antenna tuning Sat Jun 06, 2020 2:39 pm
So I stuck the antenna back up today, (in an inverted V due to space) SWR was sky high and gradually shortened it and re tested and was still high until it just dropped off a cliff. Basically 1:1 at both ends of the band. Heard a small bit of chatter on 27.555 but I’m getting some really bad QRM. Not sure if this is because my power supply is about 1.5m away from the radio or just due to the fact that QRM is almost a guarantee in a relatively built up area.
Wilko88 New Member
Call Sign : 26-CT-3558 Posts : 2 Times Thanked : 0 Join date : 2020-05-18 QTH or Location : Bracknell Equipment Used : None Yet
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Jun 07, 2020 8:41 am
Hi - welcome to the world of interference, which is sometimes not a nice place. If you’ve mounted the dipole on a hand rail as in the picture, I’d just try moving it. Pickup from nearby ADSL broadband cables and AC power cables would be my first thought. Re the power supply question - perhaps try bringing the antenna end close to the supply and see if it gets worse and worse. I have also tried a car battery to power the radio and turned the house power off to try to find the noisy thing, if that makes any sense. Happy hunting .
MrFendt New Member
Call Sign : 29-CT-024 Posts : 32 Times Thanked : 0 Join date : 2020-04-27 QTH or Location : Ireland/Germany Equipment Used : Team CB/FX mobile & 1.5m orbitor. Sirio HP 4000/Maas DP-27 & Grant 2 premium
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Jun 07, 2020 9:14 am
Thanks for the feedback Wilko88. My intention was never to have a permanent homebase as it so easy for me to drive 25 mins and be at ASL 4000ft which is why i'm predominantly static mobile but i did put this up to see if i could have some QSO from home but im not going to put massive effort into eliminating the noise. I will bring the dipole out with me mobile and string it up off a tree so all is not lost.
73's Mark
madmax New Member
Call Sign : 13-CT-139 Posts : 24 Times Thanked : 0 Join date : 2023-12-13 QTH or Location : Neustadt, Rhineland-Palatinate, Germany Equipment Used : Kenwood, Quansheng, CRT SS9900 v4, Dipole Age : 44
Subject: Re: MAAS DP-27 dipole antenna tuning Sat Feb 03, 2024 11:42 pm
I have this antenna recently, and something confuses me about the settings. If anyone knows or has experience... Is it allowed to adjust the SWR by shortening or lengthening the ends? Or do the ends always need to be the appropriate length for the frequency at which the antenna is used?
The second thing that interests me, if anyone has an idea how to set it up to achieve the best performance for DX... My idea was to have it in an inverted V.
Image
GaryWilson CT Directors
Call Sign : 26-CT-1836 Ham 2E0GGQ Posts : 4196 Times Thanked : 353 Join date : 2019-06-27 QTH or Location : Redcar, North Yorkshire. Equipment Used : Radios & Wires & Stuff! Age : 59
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Feb 04, 2024 12:26 am
Hello Dejan,
Yes you will need to lengthen or shorten the legs to tune the antenna to the frequencies that you are using. A dipole should cover the majority of the 11 meter band with an acceptable SWR.
The inverted V configuration will be fine for DX and should also help a bit with local contacts as well.
Best 73 Gary.
madmax New Member
Call Sign : 13-CT-139 Posts : 24 Times Thanked : 0 Join date : 2023-12-13 QTH or Location : Neustadt, Rhineland-Palatinate, Germany Equipment Used : Kenwood, Quansheng, CRT SS9900 v4, Dipole Age : 44
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Feb 04, 2024 9:17 pm
GaryWilson wrote:
Hello Dejan,
Yes you will need to lengthen or shorten the legs to tune the antenna to the frequencies that you are using. A dipole should cover the majority of the 11 meter band with an acceptable SWR.
The inverted V configuration will be fine for DX and should also help a bit with local contacts as well.
Best 73 Gary.
Hello Gary, Thank you for the comment. It confused me that it's a bit longer than it should be according to the calculation.
Here is the image, as seen by the Nano VNA:
73's Dejan
Last edited by madmax on Sun Feb 04, 2024 9:58 pm; edited 2 times in total
GaryWilson CT Directors
Call Sign : 26-CT-1836 Ham 2E0GGQ Posts : 4196 Times Thanked : 353 Join date : 2019-06-27 QTH or Location : Redcar, North Yorkshire. Equipment Used : Radios & Wires & Stuff! Age : 59
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Feb 04, 2024 9:31 pm
Hello Dejan,
The legs of an inverted V dipole will need to be a little bit longer than those of a horizontal dipole. If you used a calculator for a horizontal dipole this is why you're experiencing a difference. The height of the ground it's mounted will also effect your results.
Best 73 Gary.
madmax likes this post
madmax New Member
Call Sign : 13-CT-139 Posts : 24 Times Thanked : 0 Join date : 2023-12-13 QTH or Location : Neustadt, Rhineland-Palatinate, Germany Equipment Used : Kenwood, Quansheng, CRT SS9900 v4, Dipole Age : 44
Subject: Re: MAAS DP-27 dipole antenna tuning Sun Feb 04, 2024 9:55 pm
GaryWilson wrote:
Hello Dejan,
The legs of an inverted V dipole will need to be a little bit longer than those of a horizontal dipole. If you used a calculator for a horizontal dipole this is why you're experiencing a difference. The height of the ground it's mounted will also effect your results.
Best 73 Gary.
Then everything should be OK
I live on the fourth (last) floor. I am at an altitude of around 200 meters above sea level.
73's Dejan
madmax New Member
Call Sign : 13-CT-139 Posts : 24 Times Thanked : 0 Join date : 2023-12-13 QTH or Location : Neustadt, Rhineland-Palatinate, Germany Equipment Used : Kenwood, Quansheng, CRT SS9900 v4, Dipole Age : 44
Short update. After just three months of use, I managed to burn out the balun. I wouldn't recommend connecting this antenna to the amplifier. The balun can barely handle 5 times less power than declared.