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Mobile HF questions

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M Rose

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La Grande, Oregon, USA
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As many of you who have been fallowing along on the “Adventure Machine” might already know, I’m adding Mobile HF capabilities to my comms set up. Right now I have an Icom IC-7100 running ham sticks for each band I want to use. These work ok for 10-20m, but the bandwidth becomes very narrow above 20m and changing bands is a real pita.

As some of you know my favorite part of the amateur radio hobby is building antenna systems. My requirements are:

1) the system has to be multi band 10-75m with the priority being 75m. On 75 meter I hang out between 3.940 and 3.988 and the most important frequencies are 3.946 and 3.955 since these are the emergency frequencies used by ARES in Oregon.

2) the Adventure Machine has a fiberglass top, and I’m not willing to line the underside with metal to make a ground plane.

3) I have an ATU that I can use to tune an antenna from 10:1 SWR down to 1.1:1 SWR that I can (and probably will) install.

So as I have been looking at mobile HF Antennas and have seen 2 that might fit the bill so far. A screwdriver antenna looks interesting, but I lack the skills to make it auto tune. The second one would be the Icom AH-4 tuner with a 108” SS whip.

What are you using for HF mobile?
 
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Trad77

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As many of you who have been fallowing along on the “Adventure Machine” might already know, I’m adding Mobile HF capabilities to my comms set up. Right now I have an Icom IC-7100 running ham sticks for each band I want to use. These work ok for 10-20m, but the bandwidth becomes very narrow above 20m and changing bands is a real pita.

As some of you know my favorite part of the amateur radio hobby is building antenna systems. My requirements are:

1) the system has to be multi band 10-75m with the priority being 75m. On 75 meter I hang out between 3.940 and 3.988 and the most important frequencies are 3.946 and 3.955 since these are the emergency frequencies used by ARES in Oregon.

2) the Adventure Machine has a fiberglass top, and I’m not willing to line the underside with metal to make a ground plane.

3) I have an ATU that I can use to tune an antenna from 10:1 SWR down to 1.1:1 SWR that I can (and probably will) install.

So as I have been looking at mobile HF Antennas and have seen 2 that might fit the bill so far. A screwdriver antenna looks interesting, but I lack the skills to make it auto tune. The second one would be the Icom AH-4 tuner with a 108” SS whip.

What are you using for HF mobile?
I ran a 102" steel whip about 5 years ago with an LDG antenna tuner. I only got 40-6 meters with that tuner. I think with the AH-4 tuner, it would tune it down to 75 meters no problem. That 102" whip antenna worked pretty good however, due to the fact I had to tune it more people would here me than I could here them. My signal reports were great but I could almost always just hear them. my signal would be 559 and theirs would be a 339 or so. on 10 and 12 meters I could bypass the tuner all together. I made some great contacts on 10 meters without the tuner. I say go for it and test it out... thats the fun part right?

OH! My curent mobile set up is a Yaesu FT891 with the ATAS120A screwdriver antenna. Fantastic set up. I work LOTS of POTA with that thing.
 
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Prerunner1982

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I am not sure a tuner will tune a 102/108" to 75m very well but give it a shot.
Have you looked at the Wolf River Coil or making one of your own?
 
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J.W.

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If you want 10-75 while moving, a screwdriver is about your only option. They are expensive but they work. The Yaesu ATAS system is nice because of the tuning interface but I like the Tarheel a bit better.

If you don't need to be moving while TX/RX but just want to take the shack with you, I have fallen in love with the Buddistick Pro. It's a loaded coil vertical like the Wolf River Coil but it uses a single elevated radial instead of multiple radials on the ground which makes it incredibly fast to setup and you fine tune the antenna by adjusting the length of the radial.
I have a mount on my roof rack for the Buddistick and I can be setup and calling CQ in under 5 minutes. To get 80m with the Buddistick, you'll need to get the lowband coil or a few extensions but it can be done.

Any of these options are going to have a fairly narrow bandwidth for 40m and up but that's the tradeoff for a loaded antenna. At least they can all be adjusted quickly to be viable.
 

M Rose

US Northwest Region Director
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Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
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Rose
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20990

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KJ7MFV
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US ARMY Retired
I am not sure a tuner will tune a 102/108" to 75m very well but give it a shot.
Have you looked at the Wolf River Coil or making one of your own?
I’ve seen the Wolf River Coils and have been tossing around an idea to make one for 80m and possibly 40m with a bypass switch for 10-20m

I have an LDG AT-200Pro II for my ATU. To hook up to my 102” whip, do I need to use a bulan? Or just hook coax strait to the mount (center conductor to whip, braid to the body ground)? Or try it both ways?
 

M Rose

US Northwest Region Director
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Member

Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
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Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
If you want 10-75 while moving, a screwdriver is about your only option. They are expensive but they work. The Yaesu ATAS system is nice because of the tuning interface but I like the Tarheel a bit better.

If you don't need to be moving while TX/RX but just want to take the shack with you, I have fallen in love with the Buddistick Pro. It's a loaded coil vertical like the Wolf River Coil but it uses a single elevated radial instead of multiple radials on the ground which makes it incredibly fast to setup and you fine tune the antenna by adjusting the length of the radial.
I have a mount on my roof rack for the Buddistick and I can be setup and calling CQ in under 5 minutes. To get 80m with the Buddistick, you'll need to get the lowband coil or a few extensions but it can be done.

Any of these options are going to have a fairly narrow bandwidth for 40m and up but that's the tradeoff for a loaded antenna. At least they can all be adjusted quickly to be viable.
I would like to be able to be driving and monitor 75m, transmitting while driving on HF isn’t as important as it will be to be able to listen.

Once I’m to my location I have plenty of antenna options to utilize. Getting on air remotely isn’t my issue, it’s while driving that I’m trying to solve.

So let me give the situation in which I’m facing:
My role in ARES is a two part role. First I am one of six operators trained to work in the EOC (Emergency Operation Center). Most times this will be my only place of duty, but my second duty is to be ready to deploy a UHF/VHF cross band repeater for connecting other agencies to the EOC on moments notice (usually told while sitting the EOC that we need the repeater set up at XYZ coordinates). I then take the box out to the field site and set up the repeater and then my base of operations depending upon how long our services are needed and how many repeaters I’m setting up.
While driving to my location, I need to be able to monitor 3.955 or 3.946 to see if anything outside of my county’s area of responsibility is going to influence my mission, meanwhile I will be in contact with the EOC via UHF or VHF simplex and tracked via APRS.
Once I have set up and tested the Cross Bands; I will then set up my HF station as a remote relay station to relay traffic from other counties and possibly state officials back to the EOC and vice/versa. I will also have to use Winlink to send out SITREPs and other essential documents to both the EOC and to the state.

This all falls on me because I am the only person on our ARES Team that has the ability to get out to the remote outlying regions and sustain myself for up to a month if needed by vehicle only. Several members of the team have RV trailers that are set up as their portable station, and while they can stay comfortably for months on end, they can’t get as deep into the mountains as a single vehicle without a trailer.

I hope that this helps explain that what I need to accomplish isn’t just to have fun talking on the radio making contacts, but could also be the means of saving lives or property.
 

Prerunner1982

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I’ve seen the Wolf River Coils and have been tossing around an idea to make one for 80m and possibly 40m with a bypass switch for 10-20m

I have an LDG AT-200Pro II for my ATU. To hook up to my 102” whip, do I need to use a bulan? Or just hook coax strait to the mount (center conductor to whip, braid to the body ground)? Or try it both ways?
Not really a balun per se as the vertical antenna and the coax are both unbalanced but a choke certainly wouldn't hurt anything.
 
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M Rose

US Northwest Region Director
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Member

Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
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Rose
Member #

20990

Ham Callsign
KJ7MFV
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US ARMY Retired
Not really a balun per se as the vertical antenna and the coax are both unbalanced but a choke certainly wouldn't hurt anything.
Awesome, so no need for the 9:1 transformer I just use my 1:1 Coaxial choke wound on a T230-43 toroid.
 

Prerunner1982

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Awesome, so no need for the 9:1 transformer I just use my 1:1 Coaxial choke wound on a T230-43 toroid.
A 9:1 may be good for 40 and 75 to make it easier on the tuner but not sure how well that would work for 10-20.

I was really just thinking a choke in regards to common mode current/RFI.
 
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M Rose

US Northwest Region Director
Expedition
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Member

Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
Last Name
Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
A 9:1 may be good for 40 and 75 to make it easier on the tuner but not sure how well that would work for 10-20.

I was really just thinking a choke in regards to common mode current/RFI.
I was thinking the same thing in regards to the choke and CMC/RFI.

I think I will do some experiments both ways… with and without the 9:1 transformer…

I just thought of something, I can run two coax cables off of the mount, one goes into both 9:1 unun and choke, where the other coax goes into just a choke. My LDG tuner can then select which to run unun or just choke. I would just need the connector easily accessible so I can add extra coax for stationary use.
 
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J.W.

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While driving to my location, I need to be able to monitor 3.955 or 3.946 to see if anything outside of my county’s area of responsibility is going to influence my mission, meanwhile I will be in contact with the EOC via UHF or VHF simplex and tracked via APRS.
If you really only need to listen to those two frequencies, get a SWL radio and keep it in your truck. If you want the option to transmit, get a hamstick and tune it for that range. They are high Q but will be fine for that range. Hamstick and a well-bonded vehicle mount will be many hundreds of dollars cheaper than a screwdriver.
 

M Rose

US Northwest Region Director
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Explorer I

5,171
La Grande, Oregon, USA
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Michael
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Rose
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KJ7MFV
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If you really only need to listen to those two frequencies, get a SWL radio and keep it in your truck. If you want the option to transmit, get a hamstick and tune it for that range. They are high Q but will be fine for that range. Hamstick and a well-bonded vehicle mount will be many hundreds of dollars cheaper than a screwdriver.
Already have the ham sticks… while they work, I have to stop and change out between 80 and 40m. Most of our Comms are on 3.955 and 3.946, but our backup frequencies are on 40. And yes I have to be able to transmit while driving as well… 95% receive and 5% transmit. But the possibility of me having to be a roving station is there as well which would mean 50/50 split receive and transmit.

the other problem with hamsticks as you mentioned is bonding… I have to put something under or over my roof and then bond it to my body and frame… that’s not going to happen.
 

Frdmskr

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So I ran a Tarheel Model 75 screwdriver for years with my TS480sat. Did not mount it on my 4Runner when I got a new one as I was afraid of it ripping off in trees.

If you research Breedlove Mounts you will see they have some beefy options (assuming you opt not to use your trailer hitch. If you do go with a screw driver on a quarter panel mount then keep a Hustler 54” solid stick (6m) and coulda with whips for use in wooded areas. 10/17/20/40/60 were the ones I used when in the woods. It’s much cheaper to replace a coil than a screwdriver and those Hustlers, while not perfect, will serve you well in the woods.

Just a thought and good luck!
 
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J.W.

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the other problem with hamsticks as you mentioned is bonding… I have to put something under or over my roof and then bond it to my body and frame… that’s not going to happen.
You’re going to have that same problem with just about any antenna you choose so that’s a wash on the decision making process. And you don’t *have* to put something on your roof. I know several people that run bumper mounted hamsticks. No, it’s not the same as a roof mount and yes the radiation pattern is a bit wonky but they do work. Every antenna is a compromise. The trick is figuring out how much compromise you can work with.

As has been mentioned several times already, a screwdriver setup is probably going to be the best option for what you want. Are they expensive? Yes. But they will do multiband while moving. Any other choice is going to limit your capability In exchange for saving money.
 

M Rose

US Northwest Region Director
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Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
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Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
You’re going to have that same problem with just about any antenna you choose so that’s a wash on the decision making process. And you don’t *have* to put something on your roof. I know several people that run bumper mounted hamsticks. No, it’s not the same as a roof mount and yes the radiation pattern is a bit wonky but they do work. Every antenna is a compromise. The trick is figuring out how much compromise you can work with.

As has been mentioned several times already, a screwdriver setup is probably going to be the best option for what you want. Are they expensive? Yes. But they will do multiband while moving. Any other choice is going to limit your capability In exchange for saving money.
I figured a screwdriver antenna is my best bet.. I even mentioned that in my first post. So thank you guys for confirming my suspensions.

Im still going to play around with my ATU and whip to see how well I can get it to work while I wait for the ability to order a screwdriver antenna.
 

M Rose

US Northwest Region Director
Expedition
Benefactor
Member

Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
Last Name
Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
So I ran a Tarheel Model 75 screwdriver for years with my TS480sat. Did not mount it on my 4Runner when I got a new one as I was afraid of it ripping off in trees.

If you research Breedlove Mounts you will see they have some beefy options (assuming you opt not to use your trailer hitch. If you do go with a screw driver on a quarter panel mount then keep a Hustler 54” solid stick (6m) and coulda with whips for use in wooded areas. 10/17/20/40/60 were the ones I used when in the woods. It’s much cheaper to replace a coil than a screwdriver and those Hustlers, while not perfect, will serve you well in the woods.

Just a thought and good luck!
I’m looking at the Breedlove mounts now. I will not be using my trailer hitch as a mounting point… unless I make a separate 2” receiver that won’t interfere with towing.

If you’re telling me to leave the screwdriver antenna at home when I head to the woods and use hamsticks, that won’t work… I already have the Shark hamsticks mounted to my quarter panel and on 75m I don’t have enough band width. 20-10 work great, I have all the sticks to work 6-75m.

I’ve been worried about mounting the screwdriver antenna in such a way that it won’t be so easy to brake in the woods. I found plans by DK3H (the person that built the original commercially available screwdriver antenna) for mounting the coil to the under side of a truck topper… I figured I could do one of several things… A) build a bracket system that would attach to the tub of the Bronco using the top mounting hardware, B) bite the bullet and finally get me a roll cage and mount the antenna coil between the cage and my roof, C) build a bracket system that would bolt to my floor using already available hardware. I’m thinking B and C are probably my best two options… if going with C, I will make it is such a way it won’t interfere when I add my cage down the road.
 

M Rose

US Northwest Region Director
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Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
Last Name
Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
Looking at the Breedlove Mounts… wow they are spendy. They look pretty, but they are no better than what I already came up with for mounts… in fact I think my custom 1/4 panel mounts are better than his… I used 8” X 8” X 1/8” steel plate welded to the inside of the rear quarter panel.
 

Frdmskr

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Honestly I was thinking if you are driving sacrifice the cheaper antenna.

What about a bumper mount on the front Aussie style? That keep you from hitting things on the side of the vehicle and you can use it to know how much height clearance you have :)

So I ran a Tarheel Model 75 screwdriver for years with my TS480sat. Did not mount it on my 4Runner when I got a new one as I was afraid of it ripping off in trees.

If you research Breedlove Mounts you will see they have some beefy options (assuming you opt not to use your trailer hitch. If you do go with a screw driver on a quarter panel mount then keep a Hustler 54” solid stick (6m) and coulda with whips for use in wooded areas. 10/17/20/40/60 were the ones I used when in the woods. It’s much cheaper to replace a coil than a screwdriver and those Hustlers, while not perfect, will serve you well in the woods.

Just a thought and good luck!
I’m looking at the Breedlove mounts now. I will not be using my trailer hitch as a mounting point… unless I make a separate 2” receiver that won’t interfere with towing.

If you’re telling me to leave the screwdriver antenna at home when I head to the woods and use hamsticks, that won’t work… I already have the Shark hamsticks mounted to my quarter panel and on 75m I don’t have enough band width. 20-10 work great, I have all the sticks to work 6-75m.

I’ve been worried about mounting the screwdriver antenna in such a way that it won’t be so easy to brake in the woods. I found plans by DK3H (the person that built the original commercially available screwdriver antenna) for mounting the coil to the under side of a truck topper… I figured I could do one of several things… A) build a bracket system that would attach to the tub of the Bronco using the top mounting hardware, B) bite the bullet and finally get me a roll cage and mount the antenna coil between the cage and my roof, C) build a bracket system that would bolt to my floor using already available hardware. I’m thinking B and C are probably my best two options… if going with C, I will make it is such a way it won’t interfere when I add my cage down the road.
 

M Rose

US Northwest Region Director
Expedition
Benefactor
Member

Explorer I

5,171
La Grande, Oregon, USA
First Name
Michael
Last Name
Rose
Member #

20990

Ham Callsign
KJ7MFV
Service Branch
US ARMY Retired
Honestly I was thinking if you are driving sacrifice the cheaper antenna.

What about a bumper mount on the front Aussie style? That keep you from hitting things on the side of the vehicle and you can use it to know how much height clearance you have :)
I was thinking of mounting the Tarheel inside my Bronco with the whip sticking out the side… if a EFHW works as an inverted L, why wouldn’t a screwdriver?
 

TahoePPV

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For HF mobile,I’ve used a Hustler whip setup with resonators for each band 10-80. I have the spring and quick disconnect as well. The mount currently use plugs into the hitch receiver. You can see a couple of the resonators just in front of the drawers.

 

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