ok thanks for the input.  what langth of random wire laying along the hedges (thats what I'll have to do) would be minimally sufficient? are we talking 50', or would 15' work?  

my tuner is a MFJ971

also, I would run a coax out to the feed point, what do i do with the outer jacket at that point?  push a short rod in the ground, or just leave it, or something else?

sorry if the questions aseem basic, but I'm kinda new.

thank you
cp

hi all,

got my hf "go kit" together. (706Mk2G, MFJ manual tuner, pc625 battery in a canvas tool bag)

i plan to use it on HF 10/20/40/80 at work on slow nights, which means some type of collapsable antenna.

i found the S9V from S9, but the review here said you really need radials.  that's not really in the cards for my site. i can place the antenna just outside the building but it will have to be very compact and inconspicuous.

I have everything else worked out including a 239->sma adapter and elbow for the small vhf/uhf whip on ant2

any suggestions for a collapsable HF solution?

thx

hi all,

i'm putting together a go-kit for my icom 706mk2g. it will also have a manual MFJ971 tuner with it.

lookin to build some kind of homebrew HF antenna (or two!)  some kind of end fed wire would be cool.  also would like an telescoping whip of some kind.

any suggestions, or anyone done this already?

OK, I read the link by VK10D Owen and am reading the others.

http://www.vk1od.net/antenna/G5RV/index.htm

Question:  how do I determine the impedence and if necessary, other parameters of the antenna as installed.  For example, I have a digital multimeter, do I simply disconnect the 239 at the end of the ladder line section of my G5RV and test ohms?

Sorry but I'm kind of new and have to start with the basics!

There is also a mention of "voltages at remote tuner". While I dont have a rmeote tuner configuration, where is the voltage (before or after the remote tuner), when does it happen (when trans,itting?) and how is it measured?

Hi Owen,

So far there seem to be different opinions. It seems that there is no clear answer on whether to run a balun, or which one.

Common mode current seems the issue.  I've seen mention of coiling the coax, and other mention that this is ineffective. There was also different approached, how many winds and around what diameter, and where to make the coil. At the junction to the ladder line seems the place.

There was also info about applying a choke to the coax. Not sure what choke or where to get one, I'll read back and re-read it.

So start with this, what is your exact proposed optimization and with what items, placed where?  Is your proposed optimization to reduce "common mode current" and why would I want that reduced, because the "unbalanced auto tuner" would not 'like' it? if so, what does that mean, does it affect the output signal from my station or impact the life of the tuner, or both, or something else?

-chris

thanks john. i think i will keep the at7000 tuner, and put the mfj in the go-kit I'm making for the 706. (thats on another thread). i suppose I could reverse them, or just run 2 manual tuners but I have these two, and I do like turnng knobs but also enjoy the small footprint of the AT7000, SEC1223 PS and 7000 radio on my desk.  the G5RV has served me fairly well so far as I can tell. I made a contact in Spain the other night, my first overseas contact. I am also a minor / occasional SWL listener, and have an old Hallicrafters SX71 that need work. I almost sold it on ebay when someone asked for proof that it works. I started making a video of it, and having become a Ham and having the G5RV, thats what I hooked up to it. Immediately grabbed a 40m SSB conversation between FL and TN or something close, and it sounded so nice... (other than some ongoing drift)  So I cancelled the auction and plan to get it overhauled. I had never had a real antenna hooked to it before. Just random wires not very long. Plus my old house had pretty tough QRM from nearby wires. Had no idea I could call the power company to fix that until I became a ham and someone told me.

So anyway, the focus here was to decide whether to keep the AT7000 and that depended on whether the SWR difference between the MFJ and the AT was significant. Looks like it is not.

Now on to making the 706 Go kit, have the odyssey 625 battery, a tuner, and power connectors etc. just need to start reading on how to make portable antennas. If I could find a whip to handle 2m and 10m, and maybe 6m that would be great. the HF can be some kind of wire antenna perhaps that can be unspooled and hung up somewhere.

just to give an idea where this is all going, and why I needed another tuner.

anyway thanks again for the info and best regards

thanks, what is foldback, and how would I know?  during tuning with a AM ddad carrier, my 100watt transmitter seems to show around 35watts on the front panel (even on 1:1 swr). can I assume that this acceptable, and basically getting full power?

and also (this may be another topic), if that is basically full power out, how can I best know what the antenna is actually radiating out into the ether?  

finally, lets say an answer comes back how to check what the antenna is actually radiating, and it turns out to be near optimum. does that mean that recieve performance on that band is also optimal for that antenna?

not sure if Im asking these things right, but I am learning for sure, so thank you all.

this is all very interesting info so thank you for the replies, and yes I am a new ham operator. got my general ticket last spring.

anyway, the real question here is should I keep the AT7000 if it tends to give 1.75:1 SWR, (vs closer to 1:1 with the manual tuner)?

what is the real actual transmit power and reception performance difference between the two if any, with those results?

thats the key question I should address first.

(then start thinking and learning about various antenna choices)

john,  your comments that I do not need balun after all, brings me back to square one.

my MFJ manual tuner can tune way better SWR than the at-7000, which is why I assumed using it with a ladder-line G5RV with no balun was the reason.

80m  1.25MFJ   vs 2.0 AT7000
40m  1.25MFJ   vs 1.75 AT7000
20m  1.00MFJ   vs 1.25 AT2000

another interesting observation is that if I tune the AT7000 at 20m, then go to 40m (and dont touch the tune button), it's got better SWR than if I tune it there.

i do need to decide if I will ask for a refund from the seller, are you sure a Balun wouldnt help?

also, you say that since I have coax up to the ladder line, I dont need the balun, but how else would I feed the G5RV, it has a 239 junction at the start of the ladder line, and the ladder line has to hang straight down so somehow I would have to get to that from the radio.

hi all,

i have a icom 7000, and was using an MFJ-971 manual tuner which was able to tune me up pretty good on most bands.

recently i decide to try a used at-7000 auto tuner I picked up, and it wouldn't tune as well, so THEN i started to read manual, and found that the tuner needs a balun to properly tune an antenna with ladder line.  of course I do have coax TO the beginning of the ladder line which led me slightly astray.

anyway, LDG offers 2 baluns, 1:1 and 4:1. which one would apply here?

and while we're at it, is there a better antenna (not a beam or anything that requires a mast) that I might think about buiding instead?

thanks in advance for any and all advice!

The Odyssey is a dry cell, and deep cycle capable from what I can tell. My friend has one in his airplane, left the master switch on and discharged it totally. He zapped it with a sec of reverse polarity a couple times and then gave it a full charge.  Been starting the plane ever since.  You can also fast charge that battery with very high amps, and in fact it loves it.  Being a dry cell, there is nothing to spill and it can be mounted or used in any poition.

It is also almost the exact width of the radio, and I have inquired about a custom leather bag 7"wid, 10" long, and 10" deep.  With the Radio at one end, and batt at the other, that would leave decent space in the middle for the mic, MFJ 902 tuner and a couple portable antennas.

Will have to make a snap-open flap at the heat sink, for cooling then I can run it without pulling it outta the bag.

Looking for convenience here!  

73s
Chris P

Thank You!  Mark, and the rest... the replies have given me the picture, and that battery would be in the ballpark for my purposes.  I was concerned not to waste too many "radiobucks" on a batt that would turn out simply too small, or even too large.

One possible use is on my night job where there is often kill time, and all I can use now is the 2m HT. There is even a flag pole I could house up a wire antenna if the boss isnt around.

Another purpose is just to toss it in the car, on the seat. Because I drive sometimes into not so great areas, would be good to easily be able to leave it at home.

And finally, as a portable "demo station". As a relatively new ham, I'd like to be able to interest others and what better way than carry this kit in from the car into their house and fire it up on 2m, or other lower bands of antenna space permits.


I think I will look now into antenna choices, and see what existing or possibly custom leather bag could hold the kit as compactly as possible.  Also, need to look at compact tuners.

Anyway thank you again for taking the time to work the battery numbers on this project.

73s
Chris P
KB1SNJ

Hi

I'd like to throw my Icom 706Mk2g in a bag and take it portable. I was looking at the odyssey PC625 dry cell battery, http://www.odysseybatteries.com/battery/pc625.htm and wondering if anyone has any idea what kind of power drain the radio would be on such  a battery.

Or any other suggestions.

I thought about selling it and getting a 817nd but 5 watts just wouldnt be enough.

Don't care that the battery is 13 lbs, plus radio, antennas and some type of tuner. 20-25lbs is fine.

Thoughts?

OK I read it.  Still need to know if the bulkhead ground at the radio is connected to the ground rod and service ground at the service entrance. If so, then doesnt that provise a path that goes by the lightning arestor?  If now then what does the bulkhead ground get connected to, a separate ground rod?  Confused.