hf radio multi tap aerial
Submitted: Saturday, Dec 29, 2007 at 01:51
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dandy
new to hf radios. found codan 8525 radio recently andi am getting it ready for trip. have replace eprom with upto date frequencies. I have the old multi tap aerial. which only has a few rfds & private channels. how close do the frequencies have to match &what damage will you do if you use it on the close as possible frequencies. Ihave ordered anew aerial but will be a few weeks away. is this old one any good as aspare etc. thanks in advance AGROE
Reply By: Member - Doug T (FNQ) - Saturday, Dec 29, 2007 at 02:09
Saturday, Dec 29, 2007 at 02:09
Before I got my new 5 tap for VKS the old antenna was only good for Ch 2 and it was 50kc out and worked OK , say if you had a 27mhz CB and the SWR was set for Ch 8 , 27.055 it works OK on Ch 40 27,405 making it 350kc difference so you have a bit of tollerance to play with.
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AnswerID:
278837
Reply By: 96 GXL 80 series - Saturday, Dec 29, 2007 at 02:10
Saturday, Dec 29, 2007 at 02:10
Dandy,
how close to the frequency are you talking?
If it is a long way out you can cause problems with the final transistors etc.
Does the radio come with a Tuner?
If the RFDS frequencies match up, you will be able to operate it on those.
AnswerID:
278838
Reply By: Member - Stephen L (SA) - Saturday, Dec 29, 2007 at 08:01
Saturday, Dec 29, 2007 at 08:01
Hi dandy
Make sure that you have the VKS 737 Frequencies fitted. Contact Steve Johnson at Johnson Electronics in Elizabeth, South Australia and he will set you in the right path.
Join the VKS network, for the best Australia wide service and coverage. These days the RFDS do not have the Radio Contacts like they had years ago, while the VKS network has more base across Australia, and in the event of any assistance, you are able to get through to one of their bases, with contact from their very friendly and helpful volunteer base operators.
I have had the Same Codan Radio that you have purchased for over 15 years, no problems at all, with a Terlin Tap antenna. Have made contact to the bases right across Australia.
All the best and make sure that you join the VKS network.
Cheers
Stephen
VKS 737 Sierra 4113
AnswerID:
278841
Reply By: Footloose - Saturday, Dec 29, 2007 at 08:27
Saturday, Dec 29, 2007 at 08:27
Depending upon the construction of the whip, even 50khz can mean the difference between full output and partial output. The Codans are quite fussy.
Best to get a custom whip, there are plenty of options.
Remember that your HF experience will only be as good as your aerial.
AnswerID:
278844
Follow Up By: dandy - Saturday, Dec 29, 2007 at 10:39
Saturday, Dec 29, 2007 at 10:39
Footloose,
the frequencieson the aerial are 2656 2708 5343.5 5 ch2360 5450 6825 6980 7952.5 10167 13521
the 7925.5 is closest to 8022 vks. is this close enough to use as abackup aerial. I have order a new aerial from terlin out backer. Just waiting for it.
FollowupID:
542922
Follow Up By: Footloose - Sunday, Dec 30, 2007 at 14:40
Sunday, Dec 30, 2007 at 14:40
Well 5450 and 7952 might be, depends on the actual units involved. There's a little trick if you have the use of an swr or antennae analyzer.
Firstly remember that the bottom part of the aerial is shorted out at a particular frequency so you'll have to work ABOVE the desired tap.
Wind some wire/solder around the whip and tape it in place temporarily. That will tend to lower the resonance.
If you want it slightly higher in frequecy, short the ends of the turns.
You'd have to play with the number and position of the turns.
NB. Dont do this without instruments, you can't really get it right without them. Try a local "Ham" operator that might be willing to assist, they're usually pretty helpful and every one will have access to instrumentation.
FollowupID:
543058
Reply By: The Explorer - Saturday, Dec 29, 2007 at 08:43
Saturday, Dec 29, 2007 at 08:43
Hello, I have used 8160 Khz on aerial for VKS Channel 2 (8022Khz)before and it has worked.
Cheers
Greg
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278846