K-40 Antenna Not Bad At All!!! I would use one!

[MudDuck442]

Just a quick post to see what others have to say. To start off, I have pretty much always used a Wilson 1000 or 5000. A couple antenna gurus that I met back a few years ago did antenna modeling in several spects of the Wilson 1000 and 5000 vs. a lot of the other CB antennas that were out on the market at the time such as the big coil type antennas like the Predator 10k, monkey made, and a few others. It turned out for MANY reasons the Wilsons came back almost every time as better performers for most situations. I say *most* situations because I do realize there is NO perfect antenna for every situation.

With that said, recently, we came across a batch of K40 antennas and their respective magnet mounts N.O.S. (new old stock) and subsequently 4 vehicles that needed installs.

I'll skip a lot of the non-important details, but basically the mobile setups were running 2970dx n2 radios, and using the K40 antennas two magnetic mount, and two permanent mount.

Once getting them all set up on the MFJ 259B antenna analyzer, it was time to get the installs all neatly done and get everything wrapped up.

Over the next few days, we would hear the users of the antennas in our group on the air, and I must say, they work great. It seems the K40 has been picked on, and under-rated a lot. The results on paper (analyzer) and also real world results were a LOT better than expected.

I would recommend a K40 to anyone that is not running a huge amount of power. We will see how they physically hold up over time in the sun, heat, wet, cold, etc but so far so good!

 

[Mudfoot]

You can mount a K40 on a moped and get a good SWR. What do these K40 users do when they want to talk a few channels above or below the normal 40?

Especially, since they be running them fancy N2's.

 

[MudDuck442]

Well, SWR is only part of the equasion, remember a dummy load gives you a perfect SWR, but SWR tells us nothing of how well an antenna radiates, and in fact in MANY situations an antenna that exhibits a low SWR over a wide range of frequencies usually is not an efficient radiator.

Check out some reading on the subject, if you are curious, a good book is Reflections, Reflections II and Reflections III by M. Walter Maxwell:

Reflections II: Transmission Lines and Antennas - M. Walter Maxwell - Google Books

And also some other online reading:

the REAL SWR page

 

[Mudfoot]

You didn't answer my question.

BTW, I'm sufficiently schooled on the topic of SWR.

 

[jazzsinger]

K40 was never a bad antenna,it just wasn't a great antenna.even in its day it was easily outgunned by the vastly superior avanti av261 (if i'm not mistaken the benchmark for all good base loaded mobile antennas even now) , its biggest drawback was narrowbandedness,

wasn't ideal for 120ch radios nevermind todays 26-30 mhz and beyond radios,even a 7 ft firestick was a better bet 30 years ago, and like wilsons their prices are shocking,


Sirio hy power,megawatt and performer range all easily beat it, come to that most modulator/bullwhip type antennas will wipe the floor with it as well.

if your using 40ch radios in a busy area and ain't into shooting skip then buy one, you want to shoot skip,operate outside 40ch or have few local contacts then there is much better value out there for less money. it has more nostalgic value than anything else.

 

[MudDuck442]

Yeah, I wasn't trying to start a debate, just saying that we got a great deal on some of them for very cheap (15.00 each) and it warranted trying them out, and most of the guys use a handful of frequencies and have made DX contacts using them as well as pretty impressive DX work for what we all expected... that's all nothing more nothing less.

As I said I have always gone with the Wilson line and have never had an issue. I even stocked up on the older models and recently installed one on the car that had been sitting for years.

I did have a question though... you said (jazzsinger) that there are better antennas out there for cheaper, I am curious, what do you recommend for the price and why?

 

[TonyV225]

I used K40 for a few years and had no problems but once I got into higher power and shooting skip 10 meters ETC I wouldnt stray from the Wilsons I run a 500, 1000 and a 5000 and have used all 3 on 10 meters without an issue. I have a pile of antennas some still in their original packaging but I just stay with Wilsos. I would however love to try the Sirio 5000 after its rave reviews. I will eventually try one out this spring or summer I suppose.

 

[jazzsinger]

Yeah, I wasn't trying to start a debate, just saying that we got a great deal on some of them for very cheap (15.00 each) and it warranted trying them out, and most of the guys use a handful of frequencies and have made DX contacts using them as well as pretty impressive DX work for what we all expected... that's all nothing more nothing less.

As I said I have always gone with the Wilson line and have never had an issue. I even stocked up on the older models and recently installed one on the car that had been sitting for years.

I did have a question though... you said (jazzsinger) that there are better antennas out there for cheaper, I am curious, what do you recommend for the price and why?

I personally use the sirio hp 4000, its never let me down, can easily handle the biggest linears I use, zetagi B300p or RM kl400 or similar, I've had amteurs disbelieving I was mobile many a time,from height it works seriously well,

I've worked ,N.ireland,Rep of ireland and northern England all on less than 300W from the hills around my city far too often and with far too much repitition for it too be propagation,its deffo line of sight. Sure they aren't the greatest built antenna but here they and matching magmount work out about £50 odds, which in my book works out about a pound a day for a year then its free for the next ten years or however long it lasts depending on your driving or in my case how many thieving junkie bastards are active.

On skywave propagation I feel confident using it, I won't talk pish about how many and where I've contacted on it as propagation decides that not the antenna, all I will say is with a couple hundred watts and my hy power even the atlantic is just a puddle to me and there is nowhere on this planet I aint confident of reaching when and if conditions allow. Here in the uk spares like whips etc are easily available,the mag or drilled so239 base can be fitted with a sirio 3/8 convertor which basically allows me to test it against any antenna with a few twists,

I've used k40's before and while they are reasonable and do work both line of sight and dx for me the sirio is much more reliable,only 3 antennas I'd use instead would be the 7ft firestick,the av261,both no longer made and a 1/4 wave whip,not ideal when moving if you don't want your bodywork ripped to shreds,I'd consider the original wallen modulator and clones as well,while not as good as the sirio its the one cheap and discreeter antenna that actually gives the sirio a good run for its money,its only fractionally down at distance.

There's very few cars in europe containing cb's that don't use sirio's antennas, we don't buy into all that audio gain and swing crap,we mostly use FM and SSB here.

Bottom line is they are long proven antennas in europe,in my city possibly the city with the most tightest c#nts (me especially included,I'm tighter than a camel's arse in a sandstorm) in Europe where poverty is rife,no serious dx'er would be seen dead without one.

I ain't gonna slag off the K40, they do a job and for many they are a happy purchase with a bit of nostalgic status thrown in,at 15 dollars a complete steal,I'm not sure if your typing from the house or jail as you definately commited daylight robbery on that one,lol, but for my love of 26mhz and linears the K40 lack of bandwidth is a serious issue,the sirio will give you a useable swr over about 2mhz with only a little drop off in performance at band edges.

End of the day your happy with it which will give you confidence in your voice,I firmly believe that alone will bring you success with the K40 where others with better antennas will fail.

If I'm honest in my opinion only the 1/4 wave whip beats a sirio on price and performance and only modulator/clones,bullwhip etc come close peformance wise but much cheaper. Anything else I personally wouldn't touch.

 

[Robb]

Think the lack of bandwidth and its power limitation is enough to pass on the K40 for me.

I had two of those K40's and I gave them away because I didn't want to mess with replacing the matching cap in the base any more.

Sirio has them beat easily in every way, and the Wilson does as well.

Seen any sandstorms lately - Jazz?

 

[MudDuck442]

Thanks, Jazz for the info.

 

[jazzsinger]

Thanks, Jazz for the info.

No problem mate, bare in mind they are my personal views and not neccessarily fact, you summed it up perfectly in one of your earlier posts when you stated there isn't one perfect antenna for every occasion, infact an antenna with high radiation angle might be ideal for a specific contact where a better antenna with lower radiation angle might not do the trip, the wise man keeps as many options open as possible and always carries spares to cover sods law.

 

[jazzsinger]

Seen any sandstorms lately - Jazz?

I try not to waste any,valuable commodity