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First time on Top Band - I have a question if anyone can shed some light?
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Lance New Member
Call Sign : 26-CT-3984 Posts : 4 Times Thanked : 0 Join date : 2021-02-10 QTH or Location : Hull - IO93-us Equipment Used : Lincoln 2+ & Yaesu 991A
Subject: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 11, 2021 12:59 am
Hello to everyone in the Lounge.
Question regarding SWR with a home brew experimental antenna I strung together to try to get on 160m. Basically, I joined two mobile antennas for 20m and 40m thread to thread with a coupler I got off a bolt-on antenna mount and removed the whips off both so I can add a wire to either end and clamp in with the grub screws - from one of those ends, I added a 20 meter wire going up toward the chimney pot - the other end has a short wire going to an external random wire auto-tuner and the joined antennas are taped to a stick nailed to a fence. All very Heath Robinson I know
The auto-tuner can get the SWR down to 1.4 using 10w - I tried it on FT8 so I could get a coverage report off PSK however... On 25w the SWR slowly creeps up to around 2.7 during the transmit time, funnily enough, my computer logged 2 contacts while I was messing around, 1 in UK and the other in N Ireland - anyways, I was wondering if anyone might have an idea as to what might be going on to make the SWR rise? I'm using Mini 8x Coax roughly 25 meters long? and there are no unun's or balun's involved outside the tuner and I've only got a 4 foot earth rod, which to be fair is a bit thin compared to a 10mm gas pipe for instance - has anyone had experience with external random wire auto-tuners? I bought it a few months ago but only just set it up today as I had the day off.
Added a pic of area coverage captured after about 10 mins of testing.
Cheers - Lance.
43CT016 Major contributor
Call Sign : 43-CT-016 Posts : 368 Times Thanked : 22 Join date : 2019-11-17 QTH or Location : Perth Equipment Used : iCom IC-7610/IC-9700/IC-705 Age : 55
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 11, 2021 6:55 am
Have the mobile antennas got loading coils on them? I assume they will have if for 20m and 40m originally. If so, see how hot they are after a transmit cycle...I reckon you're cooking them.
Victor and Lance like this post
Alan Pilot Major contributor
Call Sign : 163-CT-220... Posts : 2623 Times Thanked : 70 Join date : 2019-11-19 QTH or Location : Anglesey North Wales Equipment Used : Yaesu FT-991A,,Yaesu FTDX-10,,Icom ic-7610,,Anytone AT-D878UV PLUS",,LINCOLN II+. Age : 16
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 11, 2021 7:35 am
+1 on the above.
Lance likes this post
Lance New Member
Call Sign : 26-CT-3984 Posts : 4 Times Thanked : 0 Join date : 2021-02-10 QTH or Location : Hull - IO93-us Equipment Used : Lincoln 2+ & Yaesu 991A
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 11, 2021 12:09 pm
Thanks for replying 43CT016 & Alan - I guess you're right, they were only cheap thin things from Knight's.
Saying that, I just had a a very clear contact on 40m with EI2HPB in Sligo N.W Ireland - 5/9 from myself with very punchy modulation and R5 10 over 9 from Dave, Chrystal clear. He has a rotatable dipole and using 150w.
On 40m SWR seems stable at 1.3 with 50w - 20m is the same, who needs top band anyhow? lol
43CT016 Major contributor
Call Sign : 43-CT-016 Posts : 368 Times Thanked : 22 Join date : 2019-11-17 QTH or Location : Perth Equipment Used : iCom IC-7610/IC-9700/IC-705 Age : 55
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 11, 2021 12:23 pm
They work well on their design frequency, for what they are.
Lance likes this post
26CT867 New Member
Posts : 11 Times Thanked : 1 Join date : 2019-08-16 QTH or Location : Northumberland Equipment Used : FT991a FT51r FT817nd Alinco DR-135UK to name a few
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 18, 2021 6:07 pm
And again as above coils overheating, see exactly the same when a balun or unun is overheating, you are asking a lot of your nock up for top band Lance, I have a 40m end fed half wave wire wound around the loft 20m long which does OK tuned for 80m and will tune for 160m but wont radiate or receive very good on there, you can tune a rusty nail but it wont work as an antenna, if you want to make a short antenna for 160m google the EH antenna and look at the 160m version not that hard to make and will do a decent enough job, or get a much wire out and about round the guttering, fences trees and bushes if you have any? and make yourself a bucket sized loading coil for the end and dont forget you need a massive ground system to load it against unles its at a half wave for 160m, experimenting with this stuff is good fun but not worth damaging your coils or radio.
26CT867 New Member
Posts : 11 Times Thanked : 1 Join date : 2019-08-16 QTH or Location : Northumberland Equipment Used : FT991a FT51r FT817nd Alinco DR-135UK to name a few
Subject: Re: First time on Top Band - I have a question if anyone can shed some light? Thu Feb 18, 2021 6:21 pm
Save you some time Lance 160m EH antenna here http://www.antentop.org/014html/014_p53.htm
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Subject: Re: First time on Top Band - I have a question if anyone can shed some light?
First time on Top Band - I have a question if anyone can shed some light?