MAGNUM 257 HP Review

[Tucker442]

send it to Chris at the Radio Shop in Ontairo Ca. he is the warranty guy and a great radio tech for magnum radios, if it's new the repair will probably be free if not then his prices are very good and not a lot of down time. If that doesn't work just list in on Ebay for like an hundred bucks someone will buy it even with an issue for that money

 

[9C1Driver]

My 257HP has bad SSB TX audio brand new out of the box. The SSB TX audio sounds distorted and raspy. It sounds alot like RF getting into the modulation. However, I don't think it's an RF problem. Even reducing the RF output to only a few watts still produces the probllem. The SWR into the IMAX 2000 antenna is 1.1 @ 28.450MHz. Swapping in another HF radio into the antenna connection does not have the problem; so that removes the RF as the cause of the problem.

I did a google search on "Magnum 257HP Poor SSB TX audio" and found that I'm not only one having this issue. Some people think the top-gun modulator is the culprit because the previous version of the 257 did not have this problem and the AM TX audio of the 257HP is excellent.

I'm open to any suggestions, otherwise I have no other choice than replacing my 257HP with a different 10 meter rig.

The blue display non-RFX-75 radio's had the Top Guns for several years with little or no problems. To be honest you hardly ever heard of a 257 go bad until this newest version with the RFX-75, which is the HP version.

That said it's not the RFX units but rather, I think, some kind of a production or quality control issue. I have never seen a firestorm if problems with Magnum radio's until this newest 257. I wish I knew what the deal was.

 

[Tucker442]

it always amazies me how many people have a 1.1 to 1 swr, either everybody had a crummy meter or they just have no output power. I am creeping up on 58 yrs old, have had almost any antenna made that is under 100 dollars and have never ever had a 1.1 to 1 swr. My best has been like a 1.2 and a little bit meaning like 1.25 or more most of them have been 1.3 to 1.5 with different coax configs or just different coax at different lengths but never had a 1.1 so why don't you 1.1 guys either get a better meter or just go around the band to see it get higher on other channels that you have cuz ALL bs ASIDE not all these people have a 1.1 swr antenna unless they are like doing 2 watts

 

[Robb]

I did a google search on "Magnum 257HP Poor SSB TX audio" and found that I'm not only one having this issue. Some people think the top-gun modulator is the culprit because the previous version of the 257 did not have this problem and the AM TX audio of the 257HP is excellent.

There is NO TopGun Modulator in a Magnum 257HP!
lol!

 

[binrat]

it always amazies me how many people have a 1.1 to 1 swr, either everybody had a crummy meter or they just have no output power. I am creeping up on 58 yrs old, have had almost any antenna made that is under 100 dollars and have never ever had a 1.1 to 1 swr. My best has been like a 1.2 and a little bit meaning like 1.25 or more most of them have been 1.3 to 1.5 with different coax configs or just different coax at different lengths but never had a 1.1 so why don't you 1.1 guys either get a better meter or just go around the band to see it get higher on other channels that you have cuz ALL bs ASIDE not all these people have a 1.1 swr antenna unless they are like doing 2 watts

You mean you don't key up and turn that litle knob until the meter reads 1.0:1??

 

[hp1kpn]

Low SWR

it always amazies me how many people have a 1.1 to 1 swr, either everybody had a crummy meter or they just have no output power. I am creeping up on 58 yrs old, have had almost any antenna made that is under 100 dollars and have never ever had a 1.1 to 1 swr. My best has been like a 1.2 and a little bit meaning like 1.25 or more most of them have been 1.3 to 1.5 with different coax configs or just different coax at different lengths but never had a 1.1 so why don't you 1.1 guys either get a better meter or just go around the band to see it get higher on other channels that you have cuz ALL bs ASIDE not all these people have a 1.1 swr antenna unless they are like doing 2 watts

This is off-topic to my issue, but here's how I get the low SWR on 10 meters:
1. Start with a new IMAX-2000 antenna and trim length according to instruction to tune it to center freq of 28.4
2. Since my coax run is 85' I decided to use LMR400 coax.
3. Antenna is mounted on telescoping fiberglass mast so it can be lowered during severe weather.
4. This base installation gives me an SWR of 1.2 @ 28.45MHz on my DAIWA SWR & POWER METER even with RF output at 50W.
5. To further reduce the SWR, I installed a quarter wave coaxial sleeve inside the fiberglass mast, just below the antenna feedpoint. The coax runs through the sleeve which is attached to antenna ground at the feedpoint. The coaxial sleeve acts as a counterpoise and further reduces the SWR to below 1.2

 

[9C1Driver]

There is NO TopGun Modulator in a Magnum 257HP!
lol!

I got this from dbradiomagazine.com

The Top Gun Compressor is included in the “S” series radios and is also now included in the Magnum 257 radio. The Top Gun Compressor works in AM, FM, and SSB modes, keeping the modulation at peak performance in all these modes. This technology has been around for quite some time and was developed by the same people who came out with the SPA-1 speech processor.

 

[Tucker442]

Thats what I thought too, I had a new 257HP and it had some kind or extra little board that was soldered to the modulation circuit

 

[Robb]

FYI - the TopGun Compressor is not the same part; nor does it have the same effect as a TopGun Modulator.
The 257HP has a TG Compressor installed ONLY.

A TG Modulator works only in AM mode; not in SSB mode. If the radio has distorted audio on SSB; then I suspect the owner may have turned the mic gain up inside the mic itself too high - and/or turned up the ALC pot in the radio. If you don't have the proper equipment to make these adjustments and know how to use the test equipment; then don't mess with the radio adjustment points . . .

 

[AudioShockwav]

Top Gun Compressor, Left picture.
Top Gun Modulator Right picture
Pop the cover and see what it has inside.
The one on the right works in AM mode only.


73
Jeff

 

[AudioShockwav]

http://www.youtube.com/watch?v=HPLnZ2CTvcI
From CB RadioMag online.


73
Jeff

 

[hp1kpn]

FYI - the TopGun Compressor is not the same part; nor does it have the same effect as a TopGun Modulator.
The 257HP has a TG Compressor installed ONLY.

A TG Modulator works only in AM mode; not in SSB mode. If the radio has distorted audio on SSB; then I suspect the owner may have turned the mic gain up inside the mic itself too high - and/or turned up the ALC pot in the radio. If you don't have the proper equipment to make these adjustments and know how to use the test equipment; then don't mess with the radio adjustment points . . .

1. mic gain inside the mic is set to factory default.
2. ALC pot and all other pots set to factory default.
3. Problem happens no matter what the radio's MIC-G is set to.

I mis-spoke in my original post when I referred to "TopGun Modulator," I meant to say TG compressor.

 

[Robb]

1. mic gain inside the mic is set to factory default.
2. ALC pot and all other pots set to factory default.
3. Problem happens no matter what the radio's MIC-G is set to.

I mis-spoke in my original post when I referred to "TopGun Modulator," I meant to say TG compressor.

If you got the radio used; then someone may have messed with it.
If you got the radio new; then you have a reason to send it in for warranty repair.

 

[Turbo T]

I've ran into an issue of when I am on SSB and when I key up and just before I speak in the mic, the radio shows signs of brief modulation on the display. It doesn't always do it, just sometimes. Seems like maybe a bad switch in the mic or maybe it's in the radio itself? Has anyone else had this problem?

 

[Tucker442]

I've ran into an issue of when I am on SSB and when I key up and just before I speak in the mic, the radio shows signs of brief modulation on the display. It doesn't always do it, just sometimes. Seems like maybe a bad switch in the mic or maybe it's in the radio itself? Has anyone else had this problem?

First I would try turning the mic gain down to about half or less, that really shouldn't be a big issue as long as it is not beeping or squeeking on the air. I did have one that after cleaning the slide switch in the mic with tuner cleaner it quit doing anything weird.