K30 Tuning and Magnum 257HP

[2RT307]

I should preface this post and let everyone know that I bought the K30 for travelling in rental cars. I run a 257HP with it. I was blessed with a meeting with the world famous HomerBB today. I was travelling in NW Arkansas, and got to meet "Homer" face to face. Great guy, and a real gentleman. I got to see all the home brew antennas in his back yard that ya'll have seen posted here, as well as make a few DX contacts from his "shack".

I travel quite a bit with my job, and purchased the 257HP and K30 specifically for use in rental cars. Homer was kind enough to help me get the silly thing tuned. I had no idea that this little magnet mount antenna would be so finicky. We fiddled and fiddled with the thing, and finally got it to settle down to less than 1.4:1 on 19, and around 2:1 on channel 1 and channel 40. Yes, I realize this is a compromise antenna... but it fits in my suitcase! It is very narrow banded, and very sensitive to where it is located on the vehicle. I had a Charger rental (sweet!), and the SWR's would not get into a useable range unless the antenna was on the roof. I know that is the best location, but it looked better on the trunk. Kind of cop car/FBI... the Charger is black.

Homer suspects that the coax is pretty junky on this antenna, and recommends ferrite beads snapped close to the antenna. We tried a ugly balun type choke with the coax, and it DID help at first. We found that it wasn't necessary later, but that was with the antenna on the roof. I wonder if the wires in the rear window defroster were throwing things off, too. Tuning is in baby steps... 1/8 of an inch at a time.

I am sure Homer can add more to this if anyone is interested. The specific application probably has a very limited audience, but I wanted to pass on the info just in case someone else was out there trying to do the same thing.

Thanks again to HomerBB for all the help!

73,
RT307

 

[Shasta69]

I have a K30 and ran a Cobra 25 and Uniden PC122XL (AM/SSB).

Quite frankly, you get what you pay for. I found the coax next to the PL259 was pinching itself and ultimately broke the center core. Homer's right about the coax.

SWR's - Magnum recommends no more that 1.8 swr (check manual).

rental cars - I have run a Wilson 1000 on a rental made a 7400 QSL mile contact with a RCI2950DX barefoot in a minivan. Even though the whip is nearly 5' long and it can be stowed and flown within a flyrod case. I did however do the "motal sin" and tapped into the cigarette lighter, but it work!

As far as Magnum 257Hp radios.... check my previous posts on that!

Much Luck!....

 

[hotrod]

I should preface this post and let everyone know that I bought the K30 for travelling in rental cars. I run a 257HP with it. I was blessed with a meeting with the world famous HomerBB today. I was travelling in NW Arkansas, and got to meet "Homer" face to face. Great guy, and a real gentleman. I got to see all the home brew antennas in his back yard that ya'll have seen posted here, as well as make a few DX contacts from his "shack".

I travel quite a bit with my job, and purchased the 257HP and K30 specifically for use in rental cars. Homer was kind enough to help me get the silly thing tuned. I had no idea that this little magnet mount antenna would be so finicky. We fiddled and fiddled with the thing, and finally got it to settle down to less than 1.4:1 on 19, and around 2:1 on channel 1 and channel 40. Yes, I realize this is a compromise antenna... but it fits in my suitcase! It is very narrow banded, and very sensitive to where it is located on the vehicle. I had a Charger rental (sweet!), and the SWR's would not get into a useable range unless the antenna was on the roof. I know that is the best location, but it looked better on the trunk. Kind of cop car/FBI... the Charger is black.

Homer suspects that the coax is pretty junky on this antenna, and recommends ferrite beads snapped close to the antenna. We tried a ugly balun type choke with the coax, and it DID help at first. We found that it wasn't necessary later, but that was with the antenna on the roof. I wonder if the wires in the rear window defroster were throwing things off, too. Tuning is in baby steps... 1/8 of an inch at a time.

I am sure Homer can add more to this if anyone is interested. The specific application probably has a very limited audience, but I wanted to pass on the info just in case someone else was out there trying to do the same thing.

Thanks again to HomerBB for all the help!

73,
RT307

well id like to congats ya on meeting homer. the k30 is a decent 3 foot antenna.,
the roof is the BEST place for any antenna. and the antenna was telling ya that.,
i myself perfer the lil wil by wilson. it tunes better.a full size wilson will unscrew
and you can store the whip/ coil in your trunk.i agree id read the manual and make sure
your swr is acceptable.another idea if ya only use the basic 40 channels id look into
a cobra 25.same size radio.

 

[2RT307]

Hey guys, thanks for the responses. I haven't had any problems with my 257HP (unlike some others that I have seen post). I do have a Wilson 500 that I will probably pack on the next trip. I originally got the K30 for flying and carry on luggage. Most times on the trip to Arkansas, I need to check my baggage. So, a bigger antenna will fit. Home and I discussed it, so I am also considering a top loaded Firestick with a good mag mount with better quality coax. I would be able to fit a 3 footer in the suitcase. I know these are all a compromise, but I have to wonder if the top loaded Firestick would perform better on the roof than a base loaded Wilson 500. Time will tell!

73,
RT307

 

[Randalman]

I was using a K30 also with a Magnum 257hp but as you said it is very narrow banded so I was not using some channels because of the high SWR and I did not want to hurt my new radio. So I thought I would try a Wilson 1000 and their "short load" antenna it is not much if any longer than the K30. It worked for me I have < 1.4 at the highest and on 20 it barely moves the needle.

I was Dx ing today on sideband and got a call back from Surrey B.C. I live in Ontario. But more importantly I am heard loud and clear locally on SSB and AM at normal power.
I might be imagining it but I think it gets better Rx as well.

 

[2RT307]

I was using a K30 also with a Magnum 257hp but as you said it is very narrow banded so I was not using some channels because of the high SWR and I did not want to hurt my new radio. So I thought I would try a Wilson 1000 and their "short load" antenna it is not much if any longer than the K30. It worked for me I have < 1.4 at the highest and on 20 it barely moves the needle.

I was Dx ing today on sideband and got a call back from Surrey B.C. I live in Ontario. But more importantly I am heard loud and clear locally on SSB and AM at normal power.
I might be imagining it but I think it gets better Rx as well.

Thanks for the info, Randalman!

73,
RT307

 

[hotrod]

a 3 foot firestick MIGHT work slightly better depending on where u mount it.
trunk =if the firesticks top load is above your roof line then it just might be better
but not alot .
roof= probaly wont see any difference as both loads on both antennas will
already be above the roofline. which essencitally is what u want.the wilson 500
u mentioned mounted on the roof would be great.i had one and compared it to
the bigger brother the 1000 and the difference was only 1/2 s-unit in favor of
the bigger antenna.

 

[hotrod]

any updates on this

 

[mackmobile43]

I suggest you purchase a better antenna which will not be too difficult, the k-30 like the wilson lil-wil are junk for the simple fact it's hard enough to shunt feed and antenna that is affixed to metal and of sufficient counterpoise and then you go and throw all that out the window and try to accomplish it with a magnet mount depending solely on capacitive coupling to ground which makes tuning next to impossible as stated in the beginning of this thread with proper tuning equipment.

I would suggest the Wilson 1k in the least and your best money is spent on the Wilson 5k for a temporary ride to ride antenna and should not really require tuning between different vehicles if they are of the same size and mounting locations are the same, no doubt the middle of the roof.

 

[psycho]

Since a K30 is just a watergating antenna and being able to carry the setup in a suit case is important, just buy a 40 channel handheld radio.

 

[cbradiomagazine.com]

The K30 is a great travel antenna - I'm on the road much of the year in rentals cars and such and it fits perfectly in my bag. Now if you run it on a trunk of a vehicle it often needs more tuning than on the roof and can require cutting (which obviously is not something you can do unless you packed your hack saw). So in most cases you're best off going on the roof. Many times you'll find with just adjusting the length inside the K30 base the best you can do is a 1.4-1.8 and of course the K30 has a fairly narrow sweet spot so you'll want to set it up for where int he band you'll be operating. Since I'm mostly on 38 LSB I just set it up for that.

The K30 is far from a crap antenna, it's just a serious compromise but trying to take a radio + antenna for travel in a suitcase means compromise is often necessary.

If running a Magnum 257HP I'd turn the radio down so you aren't running full power, best to stick around 30 watts into the K30 if you can't get your SWR low, additionally you're probably using the accessory plug to power the radio and you don't want to be pulling too many amps.

When I travel I usually take a PC122 or 640E as they are the easiest to travel with for me and on SSB I find the output + K30 is easily enough to talk locally and make SSB contacts. The Magnum 257HP version wouldn't be my first choice for a travel radio due to the higher output and draw. I did however used to take my original version with me on trips and have good results, again you just have to be careful with the amperage pull in the rental car.

If you can fit a Wilson 1000 antenna whip in your bag you'll definitely do better than the K30.