best antenna for me?

[Ruffy]

But to be honest none are going to show huge improvement over your wilson, except maybe the 108" whip, I don't know why they sell 102" steel whips, back in the day only full 1/4 wave whip that were 102" were fibreglass covered, and were only so due to that fibreglass coating slowing the velocity of the signal, just like coax does. Fibreglass has a different velocity factor to air, which is why fibreglass antennas were shorter.


I await the onslaught op:op:

Soooo you think my Wilson 1k will be fine? I see other reads where they love there Wilson 1K. To me I haven't fully tested it at all. I used it in my wifes SUV on the way back home. It seemed fine but I had wires everywhere and wasnt properly hooked up at all. Just did it quick to make sure it worked

 

[Ruffy]

I was 13 years old and proved two teachers wrong, one of whom i admire greatly because he listened to reason and was open minded enough to realise a book might just be wrong, and a 13 year old might just be smarter than them both.

JAZZ 73

lol sorry I had to.

 

[The DB]

First off, just to let ya know, I was just giving you a hard time with that post...

bare in mind I'm from uk where frequencies don't have skips, so yeah a minor oversight. not to mention one most of your fellow Americans make too.

I haven't used midband for 35 years due to qrm from you guys and Italians/Spanish running mega power and mega splatter on Antiquated Modulation.

I was aware that you guys had two different 40 channel bands, I am not sure of their frequencies but thought one was the same set used here. I'm with you on the megawatt stations for shooting skip in AM. Man, what a group of idiots. And I say that publicly. SSB is superior to AM for shooting skip for several reasons. To many of my countrymen seem to think that more power is always better, but they ignore where that power is actually going as they put so little on frequency sometimes that a radio with far less power and all of its power on frequency would be 10000 times more effective...

v I'm well aware of the alpha channels and why they were restricted and also why 23 comes after 24 and 25 frequency wise as they filled in the 30 Khz jump between 22 and 23 when they added the extra 17 channels to the original 23. I've been on cb since 78, i used fcc gear for the first year or so, a president ar7 to be precise.

I figured you knew that, I was really just trying to annoy ya with that one. Perhaps someone else learned something though...

I have always found .98-.97 to be about right when building antennas, as opposed to the 95% quoted in many books and used on most antenna calculators, again its still minor, and doesn't change the fact the reason why 102" whips are too short.

velocity factor of air varies with, purity, altitude, weather, and other things too, unless you have 100% pure air which thanks to fannies at Chernobyl and your government detonating high altitude nuclear bombs, amongst many other things ain't gonna be the case, as W5LZ says its a ballpark figure , not often I agree with Doc. But was the reason i suggested 108" whips to tune out all these variable quantities.

where do you get dielectric constant of air is 1.0 ? Google it, I think you'll find others differ.

To answer the question first, that isn't what I said. I said the velocity factor of air was essentially 1. It was my way of trying to say very close to one. Unless I missed it when checking my text, every time I mentioned it I specifically used the word essentially. The dielectric constant of air at one atmosphere of pressure and no moisture is 1.00059. Is that not close enough to be considered essentially 1? Yes, air is in a constant state of flux on this planet, so it will vary, but I've yet to see a range for such variances. As the air in the area of the antenna is in a constant state of flux the velocity factor of the antenna wire itself will be in a constant state of flux. Luckily this velocity factor change from air being in a constant state of flux is minimalto the point that few people ever notice the difference...

Even more important what makes you think its resistance that causes velocity factor, i think you'll find its more due to what surrounds conductor than what conductor is made off or how conductive it is, otherwise all coax being made from copper would have the same velocity factor, it doesn't, the dielectric dictates the velocity factor not the conductor, the more air it contains the higher the figure, but none are 1 or 100%, fibre optic cables have velocity factors too, but they are pretty shit at conducting electricity.

So apparently you forgot about the part where I was talking about the velocity factor of air before typing this part up? Odd as you commented and asked a question on it...

The wire's resistance does play a part, but a very small part for just the reason you are referring to. For the same reason a PVC (or any other) insulation on the wire will also have an effect. I never once said or implied that the resistance of the wire was solely responsible for the velocity factor. I'm happy to tell you right now that when it comes to metals that any effect of resistance will be so insignificant that you can't cut accurately enough to account for it... I have stated as much in the past, on these forums, several times.

I never forgot to mention the ground losses, I chose not too, they are so unpredictable and depending on mounting location can even vary on different parts of the same vehicle. It wasn't worth mentioning as most people fail to grasp it anyway. I'm glad you do.

OK... You are correct, talk about ground losses to many people is borderline mystical in nature.

Just the same as you choose not to model lossy coils as its most likely beyond the capability of your modeling software's limitations. I ain't seen an antenna modelled yet that had the coil figured in. All I see are straight wires, not many of those in coils.

I haven't personally attempted to model coils yet primarily because I haven't had the need to. I will say this, I tend to use very high amounts of segments, or points, along any given surface just for accuracy. I tend to use far more than most people suggest, and why not, it only takes a few more seconds to run on my computer. Before I model anything like that I will likely experiment, seeing how many points I need for said coil before the pattern and other data stabilize, then double the overall amount.

Do you model real ground conditions or just believe antennas hang in mid air, cause i ain't seeing masts or coax modelled either. Would be great if antennas behaved in the REAL world as they do in cyber space, but sadly they don't.

I use the Sommerfeld Ground in nec2, although I recently was made aware of an error in the nec2 implantation of this ground model. I'm still doing research on this to determine how big of an error it is. Aside from that it is generally accepted as the most accurate model of an earth used today. I use what nec2 calls "Average Ground", and in almost all of the posts with models I mention this... If I use anything other than average ground I go out of my way to make that clear. As an added point, it is known that nec2 is not accurate when below a certain point above ground, and my models are never below this point. The nec4 engine has corrected this, however, I'm not seeing it being worth $300 for that one correction...

There are various implementations of mininec out there, and at some point I wish to take a look at them, but as if yet I have not.

When it comes to masts and a feedline that depends on the situation. I generally at some point do take a look at a few possible lengths. The thing is, it is hard to accurately model the effects of such as the real world lengths are impossible to predict, and as those lengths change so do their effects. Because of that I'm generally looking for a worst case scenario when I add those in. I have spoken to this several times, as has another on this site.

How do you know the guy who wrote the software hasn't fucked up programming it, because most of it looks seriously flawed to me. Which is why I don't bother my arse with it. Blind faith is very common, look at all the religious fuckwits in the world that follow without question and believe a wee man in the sky is looking down on their every move, don't mean they ain't deluded like those who think an A99 has more gain than a 3 element beam, blind faith again.

How do you know one guy wrote the software? The history of the nec2 engine, which most modeling programs use today, was not originally written by one person, but a group that worked for the US Navy.

You apparently haven't read all of my comments in the past on modeling. Some of them are very critical, to the point that it seems I don't trust any of it at all. There are several things to consider with modeling, I can make a model say damn near anything I want, so if it is used for advertising I am automatically suspicious, and often flat out ignore them. I've shown this in the past, have you not seen the models of the Vector 4000 that had over 100 dBi gain? If a model doesn't look right to me I don't trust it, period, and I would have no problem calling someone out on it. Modeling is a tool, much like your antenna analyzer, and should always be taken in that context. How accurate it is or isn't has a great deal with the skill of the person using the software. Would you trust that someone who for the first time picked up an antenna analyzer to be as versed at using it as you or I? It is exactly the same thing. I would actually take it to the point that if you don't really understand the theory behind antennas neither of these tools will really help you much at all.

you say you can never match to 1.0:1 with tuning in reactance, tell a swr meter that, not to mention the fact not all coax is actually 50 ohms, many are 51 or 52 ohms and other values, also you can't be assured an antenna analyser is 100% accurate, especially Mississippi's finest junk ones. There's a small thing called manufacturing tolerance that ensures that. So it really depends how low your swr was to begin with.

Ahh yes, you know I bought my VNA because I was unhappy with my MFJ right?

Let me clarify what I was trying to say about adding an impedance. If you tune an antenna to resonance, and the R value is not 50 ohms, you cannot add a single type of reactance to match it to 50 ohms without also doing something else. In my mind this has nothing to do with feedlines at all as the matching in pretty much every CB antenna, if any exist at all, its done at the feedpoint (center and top loading coils are about the only exception I can think of to that). Long story short, if you add reactance to resonance you get "not resonance". If your not at resonance, the antenna feedpoint will not provide an SWR match to a feedline, no matter what its impedance.

Is there a time when a 52 ohm feedline might actually cause an antenna to match slightly better at the point of an SWR meter? Well, yes, but you will never notice the difference as it will be less than a needles with of difference on the SWR meter at worse...

We could nitpick all day but bottom line is, anyone buying a 102" will struggle to tune it, that was the main point I was trying to convey, so outwith all these minor niggles,

is there anything wrong with my Arithmetic,

I have no complaints on either of these...

Because I've got a very high grade in it in what once was the best education system in the world? I was tested in it at Glasgow university at 11 years of age and got an A, 5 years later when it counted at the exams, I sat in the hall for 10 minutes for 100 questions and got an A again, just to prove it wasn't a fluke the first time,

I got to meet Johny Ball a highly rated mathematician at Glasgow Uni, Zoe Ball's dad, the same Zoe Ball married to Norman Cook (Fatboy Slim) and he was amazed at my mental Arithmetic, which in those days my brain wasn't as fried from weed and I didn't trust calculators, as batteries run low and they are erratic when that happens.

I also proved a teacher wrong at secondary school who dragged me to head of maths dept, as I was apparently insolent because I demanded 100/100 instead of the 99/100 she gave me from marking from a book, he got her answer the first time because he used the formula in the book the same as she did, when i pointed out the book formula was wrong he done it my way and got my answer, did it a third time and got my answer, then told her there is a big difference between insolence and confidence, He made her apologise to me in front of 30 odd 16 year olds.

I was 13 years old and proved two teachers wrong, one of whom i admire greatly because he listened to reason and was open minded enough to realise a book might just be wrong, and a 13 year old might just be smarter than them both.

Just the same as Lou Franklin got it wrong in understanding and repairing cb radios, as he used the formula for 95% (which was commonly used for making wire antennas) velocity factor instead of 100%, that's why his length was 5% out, his proof reader missed it, i didn't, i also didn't miss his claim an Avanti Moonraker has a driven quad element when in fact it is driven by gamma matched Yagi element.

I question everything, especially where figures are concerned.

JAZZ 73

I had much the same type of math experience. My problem was not showing the work, because when I worked through it on paper I would get some wrong answers... I was far better at doing it in my head, and still am, than writing it out. I learned to write down the correct answer, then do work, and if it didn't match my correct answer I would redo the work. What a waste of time that was. If they didn't grade the work I wouldn't have wasted my time with it...

Have you seen what they are trying to do with teaching math over here now? The common core crap? I hope you guys never have to deal with that nonsense over there...


The DB

 

[jazzsinger]

DB,

like you I think you know I was intentionally tugging a few strings, I think. Its safe to say we can both learn from each other, I respect much of your points and have liked many of them too over the time we've interacted, I won't answer each individual point as most of it has enlightened some, me and you included and completely baffled others, and I'll be honest and say I give no modelling any interest whatsoever as is so fallible, so I haven't seen a 100Dbi Sigma 4, but I sure as fuck would love to own one, lol.

We have covered a fair bit of ground and subject matter that will help others grasp the how's and why's and a few why nots as well, I had no intention of arguing with you merely wind you up as you and 399 have done to me, I'm Glaswegian, and typical at that, we are some of the biggest wind up merchants on the planet and I have 35 years experience bamming people up on radio, I rarely if ever lose, I have intellect way beyond my creative ability to use it positively as half the time I'm bombed out my face, I've never hid that, life hasn't been easy and I wasted a hell of a lot of talent.

I once got accused of cheating in class because like you there was no working just the correct answer, I was sat in a class on my own with teachers watching and given 100 various long division and long multiplication in my first year of secondary school, I still got 100/100 and in less than 10 mins, I got pissed off and went mad at o level exam cause I was finished and double checked in less than 10 mins, I wanted to go but minium time was 15 minutes, I pissed them off that much they let me, I still got my 100% A, only other thing was naturally gifted at was spelling, I do word grids in minutes, natural ability, I was adopted and wasn't till I traced my mother 4 years ago I found she had similar gifys, just a pity she was a mad gambler, good with numbers but not smart enough to realise they were always stacked against her, deluded she'd be the lucky one out of the thousands of mugs who lose, I'm a bit more realistic and far more streetwise growing up in the wild west of europes murder capital.

I ain't no angel by any stretch of the imagination,borderline at best, but the biggest talent I possess isn't numbers or spelling, its the ability to laugh at adversity and myself if need be and the craziest sense of humour you can imagine, I think I've took out a fair few keyboards with people spewing coffee in my time, I have one other talent but its in my past and rather it stayed there, the ability to raise hell in an empty room.

We do have 80 channels, 26.965-27.405 FM and 27.60125-2799125 with no skips, the others have same skips as yours, I use neither, I only operate ssb and when I did use FM many years ago it was mainly to source weed and other dodgy shit, or cb gear, every criminal in Glasgow had CB's in late seventies to mid 80's, that's why so many of us don't give a fuck about breaking cb laws, or any others for that matter, its the way of y city, they call it no mean city, but here is not like the states with guns at 50 yards, its up close and personal with blades etc, guns are here but usually only involved in drug deals gone bad.

I'm a culture vulture, there is no challenge for me anymore left in line of sight comms, from high ground I've worked 3 different cuntries many many times from mobile station, 26/29 and 68 divisions, I like to tall to and learn about other cultures, I consider Europe a rig check, although I talk to many on sporadic e its F layer that gets my interest, still a few challenges left there, but not through inability, mainly through not being on when it was in and point blankly refuse to work activations, They can ram their 2 dollar contributions up their arse, I ain't desperate to work anywhere and ain't competitive, I still dx the old way, surfing the band and listening for calls, not haunting 555 like its ch19, lol, I'm old fashioned, I stalk then pounce knowing there is a very high probability of success as I have supreme faith in my equipment and confidence, I know if I can't work something its not my gear just the way propagation is running.

I've bee ndoing non stop ssb almost 3 1/2 decades, with popping on and off at will, I take it for granted, and come on forums to try to give back to a hobby that has seen me through many hard times, there's only a handful of people I learn anything from and you are one of them, I'm always open to new concepts and different opinions, I've been wrong many times but I'm smart enough to realise it and learn from it.

I knew 30 years ago AM and FM were lame ducks for dx, especially AM with its phase sensitive nature, ssb doesn't have those sort of cancellation problems although can suffer it from multipath signals and changing conditions, but its the best mode for 11m by miles, in July we are supposedly getting AM/FM/SSB legalised on the 40 FCC channels and no doubt our other 40 FM phased out, can't wait for that till it returns high band to what it used to be, prime dx country with little QRM, but with UKFM offset by -3.75 Khz it causes all sorts of shit above 27.600 so leaves us 195 Khz for DX, although its not as bad now as in 80's when all 40 UK channels were 30Db over 9 of shite. Now they all sit talking pish on ch19 or 555. I always preferred 26 Mhz around .285. I like a qso, if I want a rig check I'll shout Italy on 555, lol.

At the end of the day its night, and the point I made about 102" whips are valid with or without the technicalities or the minor inaccuracies.Ccaused mainly because I was so busy over the years doing UKFM stations antennas for them and we use 20 not 19, and so do many of your countrymen, even though as you and 399 point out is erronous, I generally tune my own antennas for 27.000 as I like to cover 26-28 Mhz, and I ain't fussed about a 2.0:1 or even 2.5:1 swr, it pisses rain here nearly every day, its not even worth getting out vehicle to tune, if its lower fine, if not, fuck it, I'd be a bit more thorough on any base setup I do, but as we are temporarily mobile and magnet will be placed in a different place all the time it ain't worth bothering about squeezing every inch of performance, I rarely bother with atu's, and swr meter's are removed during use, I just do radio, burner, twig with high quality interconnects and plugs, if I get rfi I fit low pass filter to amp with double male connector, I won't use coax that ain't mil spec, if it ain't good enough for uncle sam it ain't good enough for my station, I always solder braid and centre and make my own patch leads, as I don't trust shop ones or any other type, especially crimped connectors, I don't mind paying for quality where necessary, I've been busted before, so my radios are quality but sourced cheap and I repair them, antenna is always HP4000 or Megawatt 4000 and at home I ain't got one up yet, only moved here a few years ago and other things like my surround systems and doing up the house were more important, I live in middle of 3 storey building, so coax ain't cheao and access to roof isn't possible, so only way will be to get council approval and do it legally, again not cheap, But I'll get round to it, i have everything except 20 foot mast and T and K brackets, should put antenna base about 45-50 feet in air, I have a few antennas to choose from and more on the way, just not sure whether to keep classics unopened and use sirio tornado which will do equally good job till it falls apart or put up CLR2 or something else, depends what council let's me away with, if anything, but the threat of a 100 ft temporary mast should talk them into it, lol, as you don't need permission for temporary structures I've had 3 visits from them about weed and I from the hawaii 50 and got away with them all, I know how to play their word games, even when cops found a couple of grams of quality gear I got out it on the technicality I never invited them in and they had no warrant so was an illegal entry and would have got laughed out of court, especially as my lawyer/solicitor is best in this town, the procurator fiscal was talked into dropping it by police head of drug squad as in their words not in public interest to pursue, what they really meant was not in police interest to pursue cause they fucked up and I told them my lawyer would seek officers sacked along with a few other things I ain't going into, lmao, They ain't bothered me since a year ago last good friday, I told them they'd need to bust me every fucking day at least 5 times a day to stop me puffing, I'm sure they have better things to do with their time, lol.

Ironically the only case against me I ever lost was a cb bust at 16 cause I was too stoned to be bothered even turning up at court, had I did so I might have won cause I'd have came at them in ways they couldn't imagine, I'm quite inventive when studying law and human rights, one of which is the right to use technology. I was diagnosed with anti social personality disorder which makes me a formidable and manipulative opponent and not averse to using foul means to achieve my goals, I've even faced attempted murder charges and it got laughed out of court, I was insulted by that, if I wanted too would be no fucking attempted involved. I thrive on fights be it physical or verbal or legal, I just view it as a challenge I will win no matte what.

As the comedian from my old area Clydebank Kevin Bridges says, attempt should be twice the sentence than doing it, not a lighter sentence because you were shite at it, lol, I don't know if America has a similar law, but its dumb as fuck.

Anyway there's no hard feelings from me and I saw that you we're at the wind up and retaliated accordingly, just like I did with 399, In humour rather than argumentative, and I had no idea who invented the software, but I'm glad you cab afford a decent vna, maybe you could do me a favour and tell me the optimum dimensions for an aircore coax wound rf choke at 446.100 mhz with RG213 as I plan on building a 446.1 Mhz T2LT and due to life circumstances had to sell much of my equipment 8 years ago when my family disintegrated and again 4 years ago when I made big changes in my life, as no-one here knows how to do it and I don't have the equipment to do it, but the ones I see used I have an intuitive feeling they are far from optimal.

And if they ain't optimal common mode current and lower element length won't be bang on, I'm sure you'll know how to measure the outer shield impedance with a VNA.

Believe it or not I had no idea you had a VNA or were unhappy with an MFJ, just some of the readings I see made on them when people post pics make no sense, that was total coincidence, lol.Again we're on ground where most people won't know what a VNA is or a MINIVNA, never owned one, but like a spectrum analyser I would love too, my income prohibits gear like that sadly and I'm only now getting on my feet again after rebuilding a shattered life and winning custody of my son, 12-18 year olds don't come cheap, lmao, but saves me using google cause he knows everything, in his delusion anyway

Cb is now a low level hobby to me if I'm honest, I go on forums to help others achieve what I take for granted and have done since a very young age. Putting something back into a hobby that allowed me to escape a lot of pain is why I do it, if I pick up a bit of extra knowledge then that's a bonus but not in any way my motive, I've forgot more than most ever learn, but as Einstein once said, why remember what you can read up on if you need it, although my favourite quote of his is I know of only two things in this world that are infinate, stupidity and the univers, and I'm not sure about the universe.

You take care mate, 73 Jazz.

 

[jessejamesdallas]

Boy....This thread sure took off since I was last here!

Just got one question for Ruffy regarding this statement.

I seen the predator 10k and have to say it's not ugly at all. The ugly part is the price!

"What do you consider ugly about the price of the Predator 10K?"

Prices for the Predator's start under $60...which is less than the price on the Wilson 5000...Maybe more than what your use to paying for a fiberglass antenna, or a 102" whip, but you'll be hard pressed to find anyone who has used a Predator 10K to say they are not worth the money...

You want "real world answers" from people who have used the products, and not just one mans opinion, then check around for threads on the Predator 10K Antenna's...

By the way...you'll only need one...

 

[dx31353]

Boy....This thread sure took off since I was last here!

Just got one question for Ruffy regarding this statement.


"What do you consider ugly about the price of the Predator 10K?"

Prices for the Predator's start under $60...which is less than the price on the Wilson 5000...Maybe more than what your use to paying for a fiberglass antenna, or a 102" whip, but you'll be hard pressed to find anyone who has used a Predator 10K to say they are not worth the money...

You want "real world answers" from people who have used the products, and not just one mans opinion, then check around for threads on the Predator 10K Antenna's...

By the way...you'll only need one...

I just wanted to add to JJDs reply. I just ordered my first 10k today. I ordered the single coil with a 22" shaft, a lug mount, 12' of coax and an aluminum angle mount. The total after tax and shipping was $150.00. I thought that was a darn good price for all I ordered.

Sent from my SCH-I545 using Tapatalk

 

[AudioShockwav]

I will say this.
The last P-10K I got from Kale was $85, single coil, 27" shaft and worth the money.
I will also say that Kale is a very good machinist, and builds a quality antenna.
I have other issues with the man, but his single coil antennas are a good value.
Nuff said.

73
Jeff

JJD, you sounded great the other night on .385 in my RX from your Base.
Good Talking to you.
ASW

 

[The DB]

I'm gonna let most of our discussion rest as we are really pretty far off topic at the moment, except for a question...

Anyway there's no hard feelings from me and I saw that you we're at the wind up and retaliated accordingly, just like I did with 399, In humour rather than argumentative, and I had no idea who invented the software, but I'm glad you cab afford a decent vna, maybe you could do me a favour and tell me the optimum dimensions for an aircore coax wound rf choke at 446.100 mhz with RG213 as I plan on building a 446.1 Mhz T2LT and due to life circumstances had to sell much of my equipment 8 years ago when my family disintegrated and again 4 years ago when I made big changes in my life, as no-one here knows how to do it and I don't have the equipment to do it, but the ones I see used I have an intuitive feeling they are far from optimal.

RG-213 for a t2lt antenna at 446.1 MHz and you need to know how to build an air choke for it... That is a tough one... You would need fewer windings to raise the effective choke frequency from the standard CB band, but I doubt that just decreasing the windings, even to one on the same size form, would increase the effective choking frequencies high enough to have any effect on such a high frequency. Further, making the windings smaller should also help push the frequencies in the right direction, but RG-213 has a minimum amount you can make such a winding.

Unfortunately my antenna analyzer only goes to 180 MHz which makes any testing at the 440 MHz band difficult...

I am going to need to do some research to see how they make chokes/traps at that frequency, I want to say ferrite beads are typical, but honestly I'm not sure. Most of my experience has been in the HF bands, and that is where my studies have focused...


The DB

 

[Ruffy]

Boy....This thread sure took off since I was last here!

Just got one question for Ruffy regarding this statement.


"What do you consider ugly about the price of the Predator 10K?"

Prices for the Predator's start under $60...which is less than the price on the Wilson 5000...Maybe more than what your use to paying for a fiberglass antenna, or a 102" whip, but you'll be hard pressed to find anyone who has used a Predator 10K to say they are not worth the money...

You want "real world answers" from people who have used the products, and not just one mans opinion, then check around for threads on the Predator 10K Antenna's...

By the way...you'll only need one...

Yea your right about the price. Sorry about that. I googled it real quick and seen one for like $180 and just exit the page without really checking it out.

 

[jessejamesdallas]

Yea your right about the price. Sorry about that. I googled it real quick and seen one for like $180 and just exit the page without really checking it out.

That happens...I was checking out prices earlier on eBay for a SRA 198 NC Microphone and seen them listed anywhere from $99, to $1,150.99!

"IF" these guy's get even half that for one, I have 4 or 5 of them sitting here in the house that are almost new, that I'm going to stick on there and claim they are very rare, impossible to find, not made anymore, and maybe the last ones available in the US, and list them starting at $250 each...

I figure if these guys on ebay can make outrageous claims and get people to bite, then I'm going to jump on the bandwagon before everyone wise's up!

 

[Mudfoot]

Those prices mean the seller is out of stock. It avoids relisting fees. They figure only a complete moron would click BIN. When back in stock, the price is lowered. Saves time and money for the seller when he's out of stock.

Really need a sticky on this subject. Lol

 

[jazzsinger]

I'm gonna let most of our discussion rest as we are really pretty far off topic at the moment, except for a question...



RG-213 for a t2lt antenna at 446.1 MHz and you need to know how to build an air choke for it... That is a tough one... You would need fewer windings to raise the effective choke frequency from the standard CB band, but I doubt that just decreasing the windings, even to one on the same size form, would increase the effective choking frequencies high enough to have any effect on such a high frequency. Further, making the windings smaller should also help push the frequencies in the right direction, but RG-213 has a minimum amount you can make such a winding.

Unfortunately my antenna analyzer only goes to 180 MHz which makes any testing at the 440 MHz band difficult...

I am going to need to do some research to see how they make chokes/traps at that frequency, I want to say ferrite beads are typical, but honestly I'm not sure. Most of my experience has been in the HF bands, and that is where my studies have focused...


The DB

Similarly not being an amateur and having no interest in the very expensive 934 Mhz we had back in the 80's which was barely affordable and lacking equipment for amateurs was never going to be cheap in the 80's.

The ones I have seen used have had tighter windings than your average top end of hf ones, but intuition tells me not tight enough and far far too many turns, I have obviously considered clip on ferrites as an alternative, I plan using a cushcraft ARX 450 for the job as with a great lump of basalt volacanic plug blocking my main target area and a quarry blocking me to Glasgow my home town, supplied handi antenna and upgraded na771 just don't cut it from indoors,

I have to walk to river front to get round both, I have made the trip from there but even then signal is touchy and just turning round or moving slightly can destroy signal, I generally listen for best incoming signal and obviously that will be reciprocated on the outgoing side, not sure if I can access roof of 3 storey building, but do have a satellite dish outside I don't use and could fit the Ringo Ranger there, but although I know its not ideal may be only option, I'm also aware RG213/U isn't the best option at that frequency either,

Hardline heliax with N plug would be a far better solution but very costly and even then I might still not achieve my objective, might not even be achievable from chimney or 10 foot mast on top of it, its more for curiosity than anything else,

I realise the bend ratio may not be achievable with any coax and line isolater / ferrite clip ons may be a far more productive solution as common mode current will almost definately be a certainty with that antenna, I really do need to get a vna or mini vna that can go that high or at very least an antenna analyser, I know mfj 269 will go there but it ain't gonna be most accurate tool for the job, although might be only semi affordable one, It could also be used for building an efficient T2LT as well, so it could come in useful to many people operating up there, even a swr meter for that frequency range is pretty expensive, I really just wanted confirmed my suspicion that the chokes I've seen used which resemble that on the gainmaster are not effective for the job, thanks for taking the time to answer me, I would imagine dimensions wouldn't be too far off a similar one for the amateur 70cm's band but have struggled to seek info even on that, I'm thinking same as you ferrite clip on/s is deffo way to go but was curious if it was possible with coax,

it is just a gut instinct from what I know about HF chokes that what I have seen just can't be effective as those types of chokes are very narrow banded and without sufficient choke impedance could either be useless at best and detrimental at worst.

Thanks for your effort, it is much appreciated, Jazz 73.

 

[jazzsinger]

Just out of curiosity are the predators still giving audio gain? lmao

 

[jazzsinger]

Those prices mean the seller is out of stock. It avoids relisting fees. They figure only a complete moron would click BIN. When back in stock, the price is lowered. Saves time and money for the seller when he's out of stock.

Really need a sticky on this subject. Lol

I think it would amaze you just how many morons have more money than sense and will click BIN at stupid prices, I've seen no end of shit sold on e bay at stupid prices although it must be said more often than not it is relisted due to the fact it was sellers friends shill bidding prices up, makes you wonder how many fools get caught out with this practise.

My best advice is if its a buy it now at sensible price go for it, if its an auction set your maximum price and never go over it because another will always show up at right price and there is some real decent e bayers out there,

Never watch anything as it alerts seller and stooges to shilling possibilities, get to know your pc and its responce time, run c cleaner and its registry cleaner before you bid to maximise performance, and put in your maximum bid about 30 seconds too go, then confirm it with about 10 seconds to go, that way shill bidders have no response time

I won a 300 quid odd JVC High end, Z chssis K2 interface CD player exactly that way,it cost me 20 quid plus 10 quid postage, it was the best buy I ever made on e bay, is absolutely immaculate, The seller all credit to him honoured the deal and said you got the bargain of a lifetime there, and added some you win, some you lose. He even threw in a 70 quid studio reference Cambridge audio interconnect, the feedback I gave will ensure he lost that one but will win many in the future, it was in immaculate condition, almost unused, now used daily along with my other JVC and Sony/Mission equipment and sounds simply divine, not everything about E bay or people is all bad, I honestly expected him to relist it after any excuse to get out of it, but to throw in a top grade interconnect that was never mentioned as well as take a huge loss restored my faith in humanity, I put in a 100 quid bid, unbelievably no-one else bid and I got it at start price, I guess no-one but me knew what it was, let's just put it this way, when I originally bought the system in the 80's it was the one part I would have killed for but just couldn't afford, and I have the matching Super A amp for it, all from the days when JVC made top quality shit and still does the same job today as it did 30 odd years ago, and is used every single day. That's what I call value for money. If only all e bayers were as honest, and from that if I were to ever find myslef in the same position I would do exactly what seller did and honour an agreement no matter what it cost me, you can't buy respect, but you can sure as fuck earn it.

 

[M0GVZ]

George, you can usually find lengths of second hand hard line heliax at radio rallies and its all perfectly usable. A friend of mine has accumulated quite a lot of quite decent lengths over the years, all with those big fat expensive N-type connectors on the end.

As for the chokes I think you're basically going to be bifilar winding on a suitable mix ferrite core whatever that mix would be. Is common mode even an issue on UHF though?