Author Topic: FT857D Antenna  (Read 13044 times)

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Tempstar

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Re: FT857D Antenna
« Reply #30 on: October 18, 2013, 05:18:32 AM »
I had a Hi-Q and it was a great antenna and would do 2 meter through a diplexer at 1.6:1. The downside for me was the fact that it was heavily dependent on a good ground system and had moving parts that could potentially fail (just an anal personal preference thing). I also got into the whole ALE thing for a while and needed a no-tune setup. Also, grab 5 snap on ferrites for the coax and install them outside the vehicle. I do this even with the Chameleon and it makes a big difference on the amount of RF in the passenger compartment.
 Remember too, that RF ground and electrical ground are different animals: You'll want to run a flat ground strap from the radio to the vehicle and from the antenna mount to the vehicle. The point being to make the vehicle an effective RF ground to oppose the RF energy being radiated. I learned the hard way and probably cooked some brain cells along the way. Grab a cheap field strength meter and try it inside the vehicle while operating and play with your grounding.
 Great choice on the antenna though. I get so frustrated seeing folks cheap out on the most important part of the rig and the cry about the poor results.
 As far as a tripod setup, I have a Chameleon dedicated to that. I use 3 33' stainless 3/16" cables with 3/8" rings crimped on that go under the mounting bolt of the base where it screws to the tripod, and tent stakes (they look like big nails with a plastic rope tie) on the other end. I'll try and post some pics. It does not seem to affect my signal reports much but sure gets a lot of noise off the receive side, especially electrical noise.
 Hope this helps a bit, and good luck!
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unseenone

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Re: FT857D Antenna
« Reply #31 on: October 18, 2013, 09:54:47 AM »
This does help considerably. I understand the need for grounding, but your explanation puts they why in perspective. Currently i'm running the 857D with a remote head. I have a ground strap from the radio to the body. I also have a ground strap from the ATAS120a on the roof rack to the Body Ground Point.

I ordered 5 snap on ferrite for the project, I may need more. I haven't gotten the cable yet.

How to you measure a good or a bad counterpoise is the question on my mind at this moment.

Thanks

AD

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Re: FT857D Antenna
« Reply #32 on: October 18, 2013, 10:28:27 AM »
With a counterposie ruler of course!

Probably signal strength
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unseenone

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Re: FT857D Antenna
« Reply #33 on: October 18, 2013, 01:30:03 PM »
I did a little experimenting on the HiQ with a YT-100 Tuner. You can tune it, without using the moving gadgets this way. It actually tuned better / easier this way than the Chameleon wire for whatever it is worth. Charlie said to experiment, so I experimented.

Tempstar

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Re: FT857D Antenna
« Reply #34 on: October 18, 2013, 07:48:22 PM »
For counterpoise work, 1/4 wave usually works, but any is usually beneficial. If one was the experimenting sort, one could start there and add until the SWR bottomed out. Start slightly de-tuned and work the lengths until you see improvement.
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unseenone

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Re: FT857D Antenna
« Reply #35 on: October 19, 2013, 05:15:10 PM »
Taking your advice into consideration, I re-did the ATAS120a antenna.  I had the ferrite just inside the cabin. I hope this looks good.



What wire to you recommend for counterpoise work, keeping in mind, slick and easy to work with. I was thinking of ordering SuperWire.  I would just order the raw wire, but this would give you the general idea. http://newsuperantenna.com/MR1-SuperWire-Basic-Counterpoise/

« Last Edit: October 19, 2013, 05:36:03 PM by unseenone »

AD

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Re: FT857D Antenna
« Reply #36 on: October 19, 2013, 06:32:15 PM »
I thought you could not get the Rover into the garage?
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unseenone

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Re: FT857D Antenna
« Reply #37 on: October 19, 2013, 08:04:50 PM »
We did some experimenting when we got back, and with everything bolted down tight, it clears by 1/4". I just have to be really careful to not bounce it on the 1 1/2" floor lip. So far, no hits, it just rubs the rubber door seal as you back in.

How did the show go today?
How does the wiring look?

AD

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Re: FT857D Antenna
« Reply #38 on: October 20, 2013, 07:05:49 AM »
Starts tomorrow-wed. Just hard fun driving vehicles through DC and getting looks from everyone.  People were stopping there cars, getting out and taking photos.
The only dumb question is the one that did not get asked!!

Tempstar

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Re: FT857D Antenna
« Reply #39 on: October 20, 2013, 07:28:48 AM »
Good looking job on the mount!
I sometimes assume too much, so I'll throw this out for those who may not know: RF only travels over the surface of a conductor, not through it as electrical current does, thus the importance of the flat strap Unseenone is using in his great installation.
 As for counterpoise wires, I have experimented with different lengths and diameters and have found lengths starting at as little as 1/10 wavelength to be effective. I have also tried wires electrically grounded, earth grounded, and at no ground potential, and found that the counterpoise performs well with the exception of electrically grounded, where it has the potential of picking up 60hz hum and transmission  line noise from motors and switch gear. Try to remember to treat electrical and RF grounds as two distinct systems
 I have also played around with different diameters of counterpoise wires and not found a great deal of difference in performance except when I tried 30 guage magnet wire, which was apparently almost invisible to RF.
 In short, almost anything conductive will work as a counterpoise as long as it is at RF ground potential. Don't overlook electric fence tape either. I have a dipole I made from it and it works great, rolls up small, and is broad-banded due to the multiple conductors and wide layout.
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unseenone

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Re: FT857D Antenna
« Reply #40 on: November 21, 2013, 09:47:52 PM »
So I bought a HiQ Piranha antenna, as far as screwdriver type multiband antennas go, it's one of the best out there.

I've been playing around with it on a tripod at this point. I need to have a mount built to mount it on the roof rack for mobile operations.

The issues I'm having at this point, are related to getting it "dialed in" on some bands.  It's fine on others, on SSB on 6, 10 15, 12 & 10 meters, I will get HSWR.  I have a SWR meter, but i'm not very practiced in using it, or how to get the desired result.   I'm hoping to get some advice here.  This is what I've got so far.

160m 1.910 SWR 1.0:1  335 turns
75/80m 3.837 SWR 1.0:1 693 turns
40m 7.180 SWR 1.0:1 821 turns
20m 14.291 SWR 1.0:1 933 turns
10m 28.446 swr 2.4:1 656 turns
12m 24.961 swr 1.8:1 599 turns
15m 21.276 swr 1.7:1 514 turns
17m 18.110 swr 1.3:1 839 turns

Does anyone have any advice, I think this is a bit technical.

W.Lynn

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Re: FT857D Antenna
« Reply #41 on: November 21, 2013, 10:41:25 PM »
I'm afraid I'd only be able to help in the tools & time sort of way, and you donít really need me for that.   You have more kit than I do.

Tempstar

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Re: FT857D Antenna
« Reply #42 on: November 22, 2013, 04:48:44 AM »
Anytime you run a multi band antenna, you're going to have areas of sacrifice. Your SWR readings are all great except 10 meters. The radio will handle 2.0 or less easily, and an 857 will fold back the power starting at 3:1. I'd say you're OK except 10 meters. Just check it all again when you put it on the vehicle because that big hunk of steel is going to make things change. I had to but a 5" longer whip on the Tarheel I had just to get to the 2.0 range, but Hi-Q is better stuff.
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unseenone

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Re: FT857D Antenna
« Reply #43 on: November 22, 2013, 11:17:10 AM »
What happens on the bands with higher swr is when you transmit on SSB, the peaks cause high swr, which means you end up with a chopped transmission. So I need to figure out how to get the SWR down, with matching gear, shunts, and brains. The latter being where I am running a little short.

AD

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Re: FT857D Antenna
« Reply #44 on: November 24, 2013, 01:36:05 PM »
10 is the really only  hi one you have.  Can you manually adjust the screwdriver with the meter attached to see how it effects your readings? 
The only dumb question is the one that did not get asked!!