Magnum 257 (Report)


Magnum 257 for 11m (Widebanded)


1st Impressions (Hand’s On)

Feels a bit tinny. Microphone small and light. Clarifier knob wobbly. Possibly difficult for users of regular multi-band CB radios to get familiar with the menu driven band change system. Would be difficult to function the menu system if you were driving.

Mine had been modified for 11m use and tuned by store before I received it. I only work SSB but it comes with AM and FM as well. No built in SWR meter. Signal meter reading about 50% of reference radio. 5 vrs. 9 plus. Meter calibration problem. Received audio good but internal speaker a little squeaky. The low tone switch certainly helps.

Knobs need some white marking so you can see position at a glance especially clarifier.

Clarifier works TX and RX and didn’t have to move it much off center for good audio.

It is still a CB set at heart and you have to change bands to move more than 45 channels.

Do they have a mod to just scroll thru like a normal transceiver without coming up against the end of the band? It should be an option, as should 5k/c steps. First thing I did was to fix 4 rubber stick on feet to the bottom of the radio so I could place it on the bench and keep the speaker clear. Speaker is on the bottom. Speaker is big enough to sound better than it does. TX audio is very good. When hooked up to the big amp people could not tell I was not on the TS570! (TS570 with 30 watts SSB drives this amp to 500w but the 257 drove the amp to 600 watts!) Other CB’s owned include Ham International Concorde III. (sold years ago), and a SS3900. (Totally bad) Current radios are TS570 and IC706MKIIG and FT817so it is competing with some good radios. First CB radio I have bought in 20 years.



Not much to it. Everything surface mount except electrolytic caps, cans, transistors and trim pots. Only a few connecting wires. Certainly neat enough. DC in is wound through a substantial toroid before connecting to board. Twin output transistors are connected to heatsink at rear. Doesn’t look like too much to go wrong.


On air

Frequency coverage was 25.160 thru 29.700 in 10 banks of 45 ch. Who or what operates on 25mhz? 5 memories and a last channel recall

Output on full RF power and mic gain controls is about 23 watts or so on SSB. 8 on AM and 23 on FM. SSB audio reported clean and natural under strong and weak conditions. Heatsink got a bit warm after prolonged use but cooled quickly. Ambient about 25 degrees C in the shack with the aircon on. As we live in the tropics I will probably affix a small fan to the back of the heat sink to help it out.

Readout can be either frequency to 5 places or channel number with a band letter.

Alpha channels are indicated with a small ‘a’ after the channel number. No fiddly minus 10k/c switches needed here. Each turn of the channel switch moves the frequency by 10k/c. The channel step (1,10,100 k/c) change feature is negated by the wideband mod and the only thing that can be changed under ‘step’ is where the 10k/c step starts and finishes.

The norm is to set it on 5 which means you change from 27.455 to 465 to 475 etc

If you set ‘step’ to 0 you will get 27.450 to 460 to 470 etc

If you set ‘step’ to 2 you will get 27.452 to 462 to 472 etc and so forth.

No matter what, you can’t step in 1k/c. or even 100k/c if the radio is modified for 11m.

Now I see why many European operators are using 27.572 or 27.577 rather than 27.572.5 or 27.577.5 which I would tune to with my TS570 to go between channels. Makes sense now!

Took some time to get accustomed to the band change method but once you do it becomes 2nd nature. Only problem is that you can only scroll one way. If you are on F and want to go to E you have to go through G H I J A B C D first!

But there is  a way to circumvent most of these problems and that is to use the memories.

There are 5 memories that can be programmed into buttons 1 to 5. The trick is to put the frequencies and modes you use regularly into memory so they can be recalled with 2 strokes. To access band F memorize 27.555. To change quickly to 27.550 memorize it and then you can readily use the mic buttons to move up or down to any frequency ending in zero in that band. Give me a 5k/c step please!

To drop to band E from F memorize a frequency in E and you are there in a couple of clicks. Different but it works.

The back up for the memories will only last a few days after you disconnect the radio from the power source. Should be OK in the car but if in the house you could easily loose the memories if you turn off the power supply for too long.


The Buttons and Function Switch

The function switch is the clarifier pressed in and released. The function option appears and will stay there till you do something.

Here is what they do with the 11m mod in place


1          Step     Changes the last digit of the frequency but radio still steps up in 10k/c

                        See explanation above on step

1+Func            Activates NB and ANL circuit.


2          Call      Change bands. Each click moves up another band. Up only.

2+func              Changes from Ch plus band readout to frequency. Shows alpha channels

                        correctly. Frequency readout only 5 numbers ie 27.455


3.         Scan     Scans for and waits on busy channels

3+func              Didn’t seem to do anything


4.         LCR     Last channel recall. Instantly takes you to the last channel you Tx’d on

                        for more than 3 seconds. Nifty for Qsy’s.

4+func              Didn’t appear to do anything


5          Mode   Selects the TX mode. AM, FM,LSB or USB. Each press of the buttom

                        changes the mode.

5+func              Low tone for the received audio. Works. I left it in all the time to get rid of

                        the white noise and reduce hissing.


6          M-Load Press once then you have about a second to press button 1-5 to select the

                        memory stored there. You have to be quick! Very quick or else it will

revert to the normal use of the button. This is frustrating and you should have several seconds to hit the desired memory button. before it reverts.

6+func  M-Save Stores frequency/channel to desired memory. You have plenty of time to

                        decide where to put the frequency. Not like when you are retrieving them!


Conclusion so far

A good little radio with few bells and whistles and no roger beep. Retaining the split function in the ‘widebanded’ mode would have been nice.  Receives OK and gets out with good audio. Unfortunately in this time of low sunspot you will need a linear to break in to most DX. Use the money saved ($200) over a hi power CB radio to invest in a 300 watt linear and you will have the best of both worlds. A bit fiddley to use at first but you get used to it quickly.

Not much can touch it for the price.    


I wrote the above report about a year ago when I first got the radio. It has continued to function with no problems and has become my rig of choice for listenning around and local use. Audio continues to get good comments and she drives the DX500 amp (4ea 2SC2879’s in parallel) to 450W +. Memories are great and easy to use. Only problem is the lack of back up of the memories.  2 days unplugged and everything needs to be reprogrammed. Makes it hard to sell when folks open up and see a few numbers and letters on the screen. A 9v battery back up mod would be great or a bigger capacitor. Instant 5khz switch would be a bonus. 

Suffers a bit from AM intermodulation and adjacent channel rejection a bit low but look at the price!

Very close to perfect at the moment…. 






This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s