Tuner Required?

[KD0KWW]

So.. for my newbishness.

If I were to invest in a FT-857D and pair it with the Comet UHV-6 and slap on the Comet 75/80m coil... would I need a tuner to operate safely/successfully?

I have very little HF experience, one night actually, and am working on a shopping list to scratch my itch.

Thanks,
TC

[W4PG]

I have not used that rig or antenna, but mobile antennas on 75/80 meters all present the same problem - namely that of bandwith.

Unless the coil is adjustable, and meaning you probably have to get out of the car and manually adjust it, changing your frequency by more than a few kHz is going to required changing the coil. Some things you can change but the physics of antennas isn't one of them.

The advantage of a screwdriver antenna is you can adjust it easily to change with your frequency so you obtain a decent match what-ever your frequency.

I'm not *EVEN* going to get into "efficiency" and whether one type radiates better than another.

However, in the good ham spirit we all strive for, I say put it up and see what happens!!

.............Bob

[WB2WIK]

So.. for my newbishness.

If I were to invest in a FT-857D and pair it with the Comet UHV-6 and slap on the Comet 75/80m coil... would I need a tuner to operate safely/successfully?

My first question would be where do you intend to install it, exactly?

I have very little HF experience, one night actually, and am working on a shopping list to scratch my itch.

Thanks,
TC

Cool. If this is for a home station, this antenna is a very poor choice: It's a mobile whip, and not a very good one for HF (although on VHF it's okay). It needs a very good ground plane to work, and in a mobile setup that's provided by the car if it's well attached and mounted in a good place.

It's extremely narrowband on 80m and unless you pick just one frequency and always use that one (i.e., 3810 kHz or something), you'll absolutely need a tuner.

Actually, I wouldn't use this on 80m at all. It's much better on, say, 17m or 20m as well as the normal 6m, 2m and 70cm coverage. On 80m it's pretty disappointing.

I have one in my garage, purchased brand new several years ago and only used twice. I figured someday when I have time I'll see what I can do to improve it, but initially on HF it was terrible. I did find on 2m it was quite good, and as good as my Larsen 5/8-wave NMO-150 2m whip, so that's pretty good indeed.

Where do you intend to use it, and on what bands? If you want to run 75m mobile, I wouldn't use this one, there are way better antennas that don't cost any more but are physically larger and will do much better.

[KD0KWW]

I used 80m a an example.. but this is all very valuable input! I see coils for other bands, 10/17/20/40m. My mounting plan is to use a stake mount grounded to the chassis.

So, combining this antenna, proper coil, and a tuner... could I at least expect a good match in said bands? I know performance is subjective until I actually try it... but I'm going for a confident purchase... I don't believe the Denver HRO would let me install it first

If it comes down to it I'll just go with the ATAS-120... but I am up to suggestions!

Thanks,

TC

I have not used that rig or antenna, but mobile antennas on 75/80 meters all present the same problem - namely that of bandwith.

Unless the coil is adjustable, and meaning you probably have to get out of the car and manually adjust it, changing your frequency by more than a few kHz is going to required changing the coil. Some things you can change but the physics of antennas isn't one of them.

The advantage of a screwdriver antenna is you can adjust it easily to change with your frequency so you obtain a decent match what-ever your frequency.

I'm not *EVEN* going to get into "efficiency" and whether one type radiates better than another.

However, in the good ham spirit we all strive for, I say put it up and see what happens!!

.............Bob

My first question would be where do you intend to install it, exactly?



Cool. If this is for a home station, this antenna is a very poor choice: It's a mobile whip, and not a very good one for HF (although on VHF it's okay). It needs a very good ground plane to work, and in a mobile setup that's provided by the car if it's well attached and mounted in a good place.

It's extremely narrowband on 80m and unless you pick just one frequency and always use that one (i.e., 3810 kHz or something), you'll absolutely need a tuner.

Actually, I wouldn't use this on 80m at all. It's much better on, say, 17m or 20m as well as the normal 6m, 2m and 70cm coverage. On 80m it's pretty disappointing.

I have one in my garage, purchased brand new several years ago and only used twice. I figured someday when I have time I'll see what I can do to improve it, but initially on HF it was terrible. I did find on 2m it was quite good, and as good as my Larsen 5/8-wave NMO-150 2m whip, so that's pretty good indeed.

Where do you intend to use it, and on what bands? If you want to run 75m mobile, I wouldn't use this one, there are way better antennas that don't cost any more but are physically larger and will do much better.

[W4PG]

75/80 meter mobile isn't very productive during the day . . . maybe a bit at night.

You'd have much better luck on 20 or 17 meters during the day and the antenna will give you much better coverage of the band as well without having to manually retune it.

..............Bob

[KD0CAC]

If the budget is not too much of an issue and since your already looking at the Yaesu 120 , I would buy a entry level Hi-Q antenna ,
http://www.hiqantennas.com/
For the same money I think you get a better antenna .
For less money , Ham Sticks of your choice .

[KD0KWW]

The Hi-Q looks nice! Although a lot of the pics say stealth... I'm not sure how, lol. I very much doubt I would get spousal approval for that beast, also after I purchased the required extra equipment, the antenna is approaching $400.

But I had not seen this one before, thanks for pointing it out!

If the budget is not too much of an issue and since your already looking at the Yaesu 120 , I would buy a entry level Hi-Q antenna ,
http://www.hiqantennas.com/
For the same money I think you get a better antenna .
For less money , Ham Sticks of your choice .

[WB2WIK]

The Hi-Q looks nice! Although a lot of the pics say stealth... I'm not sure how, lol. I very much doubt I would get spousal approval for that beast, also after I purchased the required extra equipment, the antenna is approaching $400.

But I had not seen this one before, thanks for pointing it out!

Huge difference between a Hi-Q (and a few other very similar antennas, with big motor driven coils and tall stature -- all of which work very well) and a UHV-6 or even ATAS-120. The Hi-Q will beat the smaller antennas by a lot. This isn't just a matter of getting a stronger signal report: It's the difference between easily making contacts, and not making any.

For performance vs. economy, it's hard to beat a well-installed 3/8-24 mount as high on the vehicle as possible with interchangeable single-band whips like Hamsticks. This means getting out of the truck every time you want to change bands; but it's very inexpensive, and on 20-17-15-12-10m they work very well; on 40m, not as well; on 80m, worse. If you use stainless steel "QD" adapters ("quick disconnects,") changing a 3/8-24" whip like a Hamstick takes all of ten seconds, maybe less if you're quick.

[N5YPJ]

I had one of these before mounted on my pick up and it wasn't good on 40 meters, I can't imagine what 80 meters would be. I've used a Hamstick on 80 meters before and when timing my calls just right in the round tables after a few calls I would get an acknowledgment of my call but too much repeating and trouble to operate regularly. What I want to say is if you are going to operate mobile then look for a better antenna. If you are operating fixed then look for a much better antenna. 80 meter mobile your better antennas will be screwdriver antennas. Fixed antennas can be a wire or trap vertical.

If it is mobile you want then Google K0BG's website. Alan has tons of info on mobiling - a virtual encyclopedia on mobile operating. Good Luck & 73 !

[KJ4RIV]

The screwdriver antenna as outlined in the ARRL antenna book (I highly suggest you get a copy if you don't have one) is fairly simple to make and can be adjusted from inside you car. You can use a radio controlled car steering servo (or conversely an airplane servo also works) to drive the antenna tuner coil. Standard servos are $10 and all you need to do is pull out the potentiometer and hook power to the motor wires with a DPDT switch through a uA7805 voltage regulator (you can get that at any Radio Shack). All you are using it for is a gearbox anyway. This would be how I'd solve the issue.

-Alex