HF Mobile Antenna

[VK3LCD]

Hi all, i am going to install an FT857 into my car. I am looking at HF antennas at present. I would like to purchase a screwdriver antenna here in Australia but not sure where to buy from. I am thinking of buying a "manual" band change antenna for a start, but, not sure what is a good brand or price. I think Terlin have a good rep But 350 etc is a bit pricey i thought. Maybe that is a great antenna for that price. I won't be doing any 4wd or outback stuff. Mainly on highway etc. Will be set up in a VT Commodore so it will be at the back of the car, will be mounted between towbar and back corner on either side. I also would like to know what auto atu's would suit my 857. The screwdriver (or any other similar antenna) obviously doesn't need a tuner but if i go the manual antenna for 6 or 12 months or so i will get a tuner. Any other hints, tips, comments most welcome.

Thanks

Gary
VK3LCD

[VK3AUU]

If you get a Terlin, you won't need a tuner. I have found that it also works on 6 metres if you put the tap on 15 metres. I don't know if the rig you intend to use has a SWR sweep such as the ICOM 706 MkIIG has, but if it hasn't, you will need a SWR indicator in the line to set it up on your operating frequency because it has a fairly narrow frequency response on most bands.

David

[VK2GOM]

HI Gary,

I run an FT857D in my 4x4, and use a Terlin Outbacker - the big one, 160m - 10m. There is also a version that does 80m - 6m, which with hindsight I wish I'd gone for.

Tuning is very narrow on it, especially on the lower bands. I set my tap on the antenna correctly, but always run it through an LDG Z100 ATU that is cable tied to the rig main unit down in the footwell. The remote head is on my dashboard. The ATU is wired to the rig such that I just push the button on the ATU, and it automatically puts the rig into Tx, does the matching, then returns everything to Rx.

As far as performance goes, I recently had a rag-chew QSO one evening with a G3 in the UK on 20m, so it definitely works.

You can use the SWR indication on the MTR mode on the rig to monitor what the rig is 'seeing' in terms of an antenna load.

Ground planes are paramount for antennas on cars. Try not to mount it in an extreme edge or corner. Middle of the car is optimum, but work out from there with an eye on practicality. When parked up static, I have three 10m retractable steel tape measures I can reel out and hook up as radials.

Also, worth a quick radio lash up first and a test whilst driving to see how much ignition/noise you get from the car. Would be disheartening to go to all the trouble of a neat installation then find you have S9 of ignition noise on all bands.

73 - Rob VK2GOM / G0MOH

[VK3XL]

Hi Garry, get in contact with FAMPARC They make their own Turlin like mobile antenna and the prices are very compeditive. I bought one that covers 80,40,30,20,17,15,12 and 10... might work on 6 as well, havn't tried that yet. Cost $135. You will have to get a base for it as well (they can supply them too). I also use a z100 auto tuner and a ic706 with my mobile setup. As far as a screwdriver antenna goes there is a bloke in VK2 that makes them. http://cust.idl.net.au/mp.jones/index.html But you can make your own if you have access to a lathe and the know how to use one.


Have fun
Mike VK3XL

[VK3BA]

G'day Gary, I concur with Mike 3XL - the FAMPARC jobbies work quite well. I've been using one on the front of the Hilux with an IC-706IIG & LDG AT7000 very successfully. Take a bit of care with the install, mainly in regards to earthing and you'll be fine. There's a bit of a pic of it on my QRZ page.

Cheers,

[VK3LCD]

Thanks for al the input so far, yeah i was gonna have a look at yours (antenna that is :> ) at the SERG hamfest Nic but you were a tad occupied. Would have loved to have heard more on 3VLY's favourite mode - DSTAR. Maybe next time we catch up....

[VK5KLV]

Hi Gary, Another course of action to consider! I have a FT857D installed in my Camry. The radio is in the boot with aYaesu FC40 Auto tuner. The tuner feeds a 2 piece whip about 3 meters long. This whip is mounted with a standard spring onto a standard Terlin style base mounted to a bracket bolted back to towbar mounts on RHS of vehicle. The whip stores easily in the boot by unscrewing the centre joint. The control head for the radio is mounted to the centre console in easy reach & view. I have a VHF/UHF whip mounted on a "Z-mount" on the RHS rear mudguard.This setup has performed very well foe just over 4 years now with trips across the Nullarbor (several) & to Alice Springs as well as many Kms of relatively local driving. Hope I have been of some help (or muddied the waters) Cheers, Les, VK5KLV.

[VK7XX]

[some text deleted] I am thinking of buying a "manual" band change antenna for a start, but, not sure what is a good brand or price.

Gary, have a look at the Opek HVT400B http://www.opektech.com/HighPerformance ... ml#hvt400b and here too http://www.universal-radio.com/CATALOG/ ... /5066.html. Yes, its a super comprimise antenna, but it cost me less than $120 delivered to the door.

I got mine from VK4ICE http://www.vk4ice.com/

73
John

[VK2GOM]

Gary,

If you wanted one of those, I have one here, that just needs the stainless whip part (which I stole off it for my Terlin Outbacker after the whip on that jumped off the antenna at 110kph and disappeared).

I'm sure you can fit any old stainless whip of around the required length and get it going. You could use springy 'piano wire' from any model shop which would work too. Still has the packet it came in, and of course the jumper band-change lead. The base is a PL259 in case you weren't aware. Covers 80m to 70cm as far as I can remember, including 6m and 2m.

$40 bucks (plus postage) and it's yours. A big saving over new for the sake of a stainless whip. If you need any more info, PM or email me.

73 - Rob VK2GOM / G0MOH

[VK3LCD]

Hey Rob, hooked up the antenna and 857 today and did a test on 80 with a couple of "locals" tonight (approx 100km away) . Seems to be working ok at this stage. Strong signals on 80 from VK2 etc. Will be doing more tests over the next week or so. I do have an s6 or thereabouts noise level in the car though. Antenna is on a boot lip mount type. I have read how most HF antennas (if not all) need very good earthing. I was thinking of moving the antenna but i guess it needs to be ABOVE all metal to work properly so i will probably leave it where it is and maybe try to ground the base a lot better. the radio will be mounted remotely (under the seat) and i think that should be grounded to the chassis as well. Any other suggestions very welcome from anyone. So far quite happy. Thanks Rob.

[VK2GOM]

Hi Gary,

Good to hear. Yes, the higher the better and above all metal to get as much ground plane as possible and not suffer detuning effects. A 3 footed mag mount is usable at HF as there is a fairly good capacitive 'connection' to the metalwork of the car. This also lets you put it in the very best spot - right in the middle of your roof.

Noise can be a stubborn gremlin to solve... On my Ford Explorer I have thick braid straps from engine to gearbox to chassis, from tailpipe to chassis, and then every door to the body, the tailgate and bonnet two straps each to the body, and another strap from the Aluminium bullbar to chassis. After spending a fortune on these straps at $14 a pop I still have about S6 of noise on HF, so most operation is whilst parked up. I think my remaining noise is ignition and/or fuel pump noise. Ferrite on the coax right where it goes into the antenna sockets on the rig can also help if it's RF-borne noise. For noise actually on the DC lines, you could try a noise choke/filter from JayCar - it goes across your battery then you take power from it. They do one which is rated 22A or so - ideal for a mobile HF rig. You could also try the trick mentioned on the forum here in another topic of bonding your negative wire from the rig to the car common earth bond point on the chassis, and not the -ve of the battery.

Look forward to working you mobile to mobile sometime! You'll love mobile HF, even if it is driving to remote spots, parking up, and working some DX! And band conditions will be getting better and better all the time as the solar cycle ramps up again.

73 - Rob VK2GOM / G0MOH

[VK4QB]

Hi Guys,
I have done research on ignition noise from a vehicle and found that most of the noise originates from the distributor, where the arcing occurs not the spark plugs which are shielded. Usually vehicles that don't have distributors have very little ignition noise. Make sure the ignition coil on the vehicles with distributor is bolted to the engine block, not the mudguard etc. Use a coaxial capacitor to feed DC to the ignition coil . Earth the bonnet with 4 straps at each corner ?? use separate earth strips on top of the rubber cushions earthing the strips to the bonnet and the body. Use an addition earth strap on the motor opposite the earth lead. Don't rely on the earth lead alone. I think the biggest problem in vehicles is ignition noise largely eliminated with computer controlled ignition systems.
Currently I have a diesel motor home. I don't use it while moving as the antenna is 12 foot long RG58 braid inside fishing rod with base at about 8 feet up. L matched to antenna with separate matching (in jiffy box)for each band. The base is earthed through the mast and has additional braid connected to the roof .SWR is 1:1 on any band 3.6, 7, 10, 14,18,21,28 mhz & 6metres Its only about 25 khz wide on 3.6 mhz and has wider bandwidth as we go up in frequency
73
Brian 4QB

[VK3PY]

I've never found bonding of doors, bonnet etc. to make one iota of difference to the ingnition noise on any of my vehicles (neither has it made any difference to the quality of the RF ground presented by the vehicle body, but that's another story). That's because a good deal of ignition noise is CONDUCTED along the cabling rather than being radiated directly to the antenna.

What has worked for ignition noise has been (a) a short bonding strap from the rig case to the vehicle body. Most HF rigs have an earthing lug on the back panel for this purpose. (b) One or two ferrite sleeves over the antenna feedline. Ideally you want to introduce 10 to 20 uH of inductance. If you think about it, any ignition noise conducted from the DC supply connection (i.e. battery in the engine compartment) will flow along the DC supply cable, over the rig case and continue along the coax cable to the earth connection at the antenna. In other words, the noise shares a common path with the signal. Not good. The earth strap mentioned above goes a long way to solving the problem. The ferrite sleeves help at higher frequencies where the earth strap may be a little too long. You could also place some ferrite sleeves over the supply cable for the same purpose. Worth a try. Take note though: for a HF installation you want the series inductance presented by the ferrite sleeves to be quite high. Those clip-on sleeves you can get from Jaycar etc. will only provide a few uH at most. Ten uH will introduce 440 ohms of series impedance at 7 MHz, just to give a guide.

One other benefit of the treatment described above is that it tends to keep RF out of the car's sensitive electronic stuff. In years gone by I've had the fuel gauge dancing around and a car radio that kept turning itself on whenever I transmitted on 40m. Now everything's happy.

Chas
VK3PY

[VK2KC]

Hi all, i am going to install an FT857 into my car. I am looking at HF antennas at present. I would like to purchase a screwdriver antenna here in Australia but not sure where to buy from. I am thinking of buying a "manual" band change antenna for a start, but, not sure what is a good brand or price. I think Terlin have a good rep But 350 etc is a bit pricey i thought. Maybe that is a great antenna for that price. I won't be doing any 4wd or outback stuff. Mainly on highway etc. Will be set up in a VT Commodore so it will be at the back of the car, will be mounted between towbar and back corner on either side. I also would like to know what auto atu's would suit my 857. The screwdriver (or any other similar antenna) obviously doesn't need a tuner but if i go the manual antenna for 6 or 12 months or so i will get a tuner. Any other hints, tips, comments most welcome.

Thanks

Gary
VK3LCD

Gary,
I have been through the mill with regard to the selection of HF mobile antenna, OPek, Outbacker, Workman, etc., but the best performer of all those is the High Sierra HS1800, motorised antenna.
It took a lot of work to instal it into the VE Commodore, has computer issues, but after a week I finished it. I love the way it tunes on the fly, I also bought a N2VZ tuner, and running a 706 Mk11G its great being able to select the frequency and hit the tune button, and it finds the lowest VSWR and thats it. Completed an east to west coast trip last year and I found it outstanding in the performance area.

I have just finished home brewing a 80 to 10m mobile fashioned on the Texas Bugcatcher, with a few changes, used a 110mm dia loading coil and a 600mm diameter capacity hat mounted right a the top, the whip wsa a recycled fibreglass HF whip 15mm in dia and 2400mm long. It outperforms my HS1800 easily!
My advice is no to bother with an Opek (useless!) or an Outbacker, I paid over $300 for mine and the Famparc antenna almost makes both of them look like a mobile dummy load!
Happy mobiling!
John
VK2KC

[VK2GOM]

Hi John,

I think a lot comes down to the installation, quality of earths, and size of available ground plane.

I worked a G station in the UK recently on 20m whilst I was mobile, and we had a good rag-chew. All on my Outbacker antenna. Works for me...

I'm intrigued as to what the FAMPARC antenna does differently, since as far as I can tell, it's a home-made copy of an Outbacker. I went for the Outbacker in the end since the quality of construction is better.

73 - Rob VK2GOM / G0MOH

[VK3FLAG]

sorry to bring up an old thread, however i just wanted to show how i have mounted my FAMPARC antenna, and I have received good reports from locally (vk3) and interstate VK2 and VK4 on 40M over the past couple of days, using an IC7000.
i made sure that the antenna had sufficient earth in order for it to perform, as recommended by the guys at FAMPARC.

[VK3DXE]

Hi Richard(?),

How do you find the strength of the lightbar mount?

I'm trying to work out the best way to mount a decent HF antenna on my Subaru Forester and it looks like either a towbar mount (not really practical for when I'm travelling, as the antenna will need to come off to open the tailgate) or on the lightbar as you've done. Did you have to do any extra reinforcement work behind the bumper? I'm guessing the bumper on your vehicle is a little more robust than that on the Subaru.

[VK3PF]

Alan,

I had a small bar welded up using Aluminium for my Forester - admittedly an old one, with the nudge bar at the front.

It is a piece of angle that fits behind the nudge bar, with 2 pieces of a rectangular extrusion cut at an angle welded to the angle section. There is a hole drilled in each "channel" section, which is then bolted down onto the original mounting place for the nudge bar - I simply removed the plastic covers and replaced the mounting bolts with slightly longer ones.

It might give you some ideas....

Cheers,

Peter VK3PF

View from above.

View from above of Subaru mount.

View from front.

View from front.

[VK3FLAG]

Hello Alan,

Yes, i had to fabricate some reinforcement brackets behind the bumper and also drilled it into preexisting holes on the body of the car.

Here is a link to more pics.

http://www.aurfscan.com.au/showthread.p ... -Rig/page3

[VK3DXE]

Thanks Peter,

My partner has the older model like yours - MUCH easier to mount things on Unfortunately the later model Foresters are more difficult. I may have to remove my bumper, work out some way to strengthen it, and then mount onto the light bar. Even mounting a "Z-Mount" bracket on the guard is difficult on the later ones. To top things off, I have the wider Aero roof bars, so mounting things on there isn't an easy solution either.

BTW, are you still active on 2m? Can't remember if we actually completed a contact when I was in Sydney (VK2DXE), but IIRC you had a reasonable signal via aircraft at times.

Cheers,