the 257HP comes with the RFX75 from the factory, the 257 (non HP) does not, it comes with dual finals instead, it does around 30-50 tuned up

 

i know that.. hence why i didn't say HP, we already had the 75 kit laying around and just bought the regular m257 and replaced the finals with the 75 kit. wasn't worth the extra cash for 15 mins worth of work. ohh btw 28 watts was the max we got out of the stock 257 (non HP).

 

I see

I have the Roadpro Titan II, which is a basically a Magnum 257 (non HP) without variable power, and with a single 2sc1969 final. I got 18 watts out of it...35-45 watts on a257 is quite doable, I have tuned 7 of them with results ranging from 30-50 watts (the 30 watt unit was weird to say the least)

 

I have a non-modified Radio Shack TRC-465 operating on 4W (12W on SSB) and using a Radio Shack 102" ss whip antenna. I know, oooooo, whoop-dee-do, right? Except the first day I fired it up, I picked up SSB stations in Minnesota, Alberta, & Virgina. The rig was about $50; the antenna was $21.

Now, I mainly got back into CB because the local clubs require it. But I also do a lot of solo rides out in the desert. I'd rather I had the capability to talk to stations in New York than a fancy new radio & short antenna, as the New York station can still call the rangers here by phone a relay a message & my coordinates. Where I go, oftentimes my 2M ham radio and cellphone are useless.

 

Well, I'll describe it as best I can....

I have two different mag mounts and two different antennas (short springer orbiter for mobile and 9ft tank whip for static). I stick the mounts in the centre of the roof with the roof bars as far front/rear as I can move them.

When I test SWR I get massively high readings (over 50:1), the more power I put in - the higher the SWR climbs. I tried coiling the cable to make a quick balun and the SWR dropped (but was still about 7:1). It has been suggested to me that this must be common mode interference so I'm looking for the right kind of ferrite split ring so I can make an ugly balun near the antenna and test again.

I bought the second mag mount to eliminate cable faults, and didn't notice any difference so I'm guessing that the cables are fine and there's something else going on.

All suggestions welcome

 

woah holly reflect batman... you got a pic of this setup?

 

A balun is not going to do you much good. Yes it will "match" the antenna to the radio, but you're not going to transmit too far, and possibly damage your radio.. If both antennas are mag mounts you have to have good contact at the base of the antenna to create your ground plane. If you have access to a DVM, or ohm meter then you can check the continuity from the PL-259 and the antenna itself. First remove the connector from the back of the radio then check from the center conductor to the radiating element, you should see zero ohms, then from the shell of the connector to the base of the mag mount with it too reading zero ohms. If that checks out then measure between the center conductor of the PL-259, and the shell which should show an open circuit (infinity). Personally I would stay away from magnetic mount antennas. Direct mounting is the way to go.

 

Gotta say, I'm getting very frustrated with the mag mounts - how two can give such bad readings I just don't know. One bad one from the batch I could understand but two seems unlikely. Am I doing something wrong by just slapping it on the roof and testing? I tried the newer one on another vehicle and got the same results.

I'm very tempted with direct mounts, but I'm confused as to how I'd get a decent ground plane with the antenna at one end of the Jeep or the other.... Can I mount onto the roofbars or is that just as dumb?

I'll do the tests you suggest as soon as I can find my multimeter.. I'm sure I saw it round here somewhere :/

 

Hate to say this but it could the quality of the antenna. You get what you pay for. If it's a mag mount you desire then investing in something like a Li'l Wil from Wilson should work. K40's are also pretty decent. Then again I haven't touched a CB since the 80's. My dilemma is staying VHF/UHF, or shoot the works and go HF/VHF/UHF.

 

Moderators....seriously...a CB Radio sub forum would be greatly appreciated. Thanks.

 

simple... just install the antenna and use a hard mount and make sure the mount is grounded!

 

Wouldn't an electronics forum with sub-forums for radios, stereos, and other gadgetry would probably be more appropriate? Just my .02...

 

yeah i already tried they wont go for it.. probably they see no money in having it.

Morat, are you using both the antennas for one radio? duel band? or they for different radios? a little more info would help. also if its a VHF/UHF radio mag mounts are not usually recommended due to grounding problems. and if the antennas are close well.. your gonna get a little reflect off each other causing SWR problems. my 2m antenna is hard mounted and my cb antenna at the moment is a mag mount.

 

are you certain you are checking the SWRs correctly? I mean are you modulating when you check them? Because you shouldn't be. SWR should not change as the power level goes up

 

I am a Super Moderator on another IB automotive forum (RX8Club). The only ones that can set this up are the Administrators. There are only 2, okcjeeper & Robb M. Robb M. is an employee of IB. He would be busy and not much help in this. I would contact okcjeeper with your request. This site does have a lot of traffic for having just 2 admins. I'll bet they are busy.
On my other forum, we have the tech forums divided into different areas of the vehicle interior, exterior, suspension .... But, this was all setup before IB bought the site about 6 yrs ago.