This is particularly useful in areas where large volumes of traffic (signals) are present. Turning the control counterclockwise reduces the receiver sensitivity. This affects the distance at which a signal can be detected. RF GAIN CONTROL: Adjusts the receiver sensitivity to both signals and background noise.Turn clockwise to increase and counterclockwise to decrease. VOLUME: Adjusts the AF gain, or volume of the received audio.
OFF: Turns the power to the radio on and off Many of these functions may change or will be disabled in expanded frequency mode. The following knob controls can be found on the Magnum 257 as specified in the owners manual. Keep in mind the two CB radios shown are single final radios that only will do around 20 watts max and don’t have near the number of features available on the Magnum 257. In the picture below with the Magnum 257 HP you’ll see two SSB radios I had on my bench: a Uniden 640e (one of the smaller SSB CB radios around) and the Cobra 140 GTL (smaller than the Cobra 148, Galaxy 959, etc.). When talking about the size of this radio you’ll hear everyone say how compact it is, but I think a picture really is necessary to give people a better idea of the size of this radio. Even after owning my original yellow model and the later blue face models I’m always impressed by just how compact this radio really is. When you open the box you’ll be greeted by the smallest SSB export radio on the market. Make note that the PEP output is incorrect (shows 30 watts on the box) and if you are buying the radio and want to make sure you are getting the new HP version look for the sticker in the upper right hand corner that says 257HP.
The features shown on the box are all correct though and point out all the advanced functions of this radio. When you see the new Magnum 257 HP box you’ll notice they are still shipping them in the old style original Magnum boxes showing the radio with the yellow display (I think Magnum must have a ton of the old boxes around since it’s been five years since the changeover to blue). The latest version of the Magnum 257 (the HP) takes the current version to the next level with the addition of the new RFX 75 final system from RF Limited, giving the radio output in the 70-80 watt range. The compressor helped maintain consistent audio peaks and provided the Magnum 257 with very consistent audio with even more punch than previous versions.
#Rfx 75 amp mod#
With the Top Gun compressor installed on the Magnum 257 the NPC mod was no longer necessary as the radio now had very solid audio on both AM and SSB. The new radio then came with a blue display and Magnum also started including Top Gun technology on the radios by adding the Top Gun Compressor. Magnum made changes to the radio in 2004-2005 and it then came with dual ERF-2030 transistors and was capable of roughly 40 watts PEP (it was advertised as 50 watts PEP). The NPC mod for the 257 was introduced shortly after, which allowed the radios to have much louder AM audio, especially if you also made the adjustment to the VR pot inside the stock microphone. The display was amber in color and the radio was very popular for SSB but many people faulted its AM performance as not being loud enough. The original Magnum 257 was a dual final radio with 1969 final transistors and was capable of around 25-30 watts PEP. In front of me I have the latest version of the Magnum 257, the Magnum 257 HP, and while it still retains much of my original radio’s looks there have been some significant changes since 2003. Originally the radio was paired with a KL203 amplifier and I made DX contacts from Africa to Chile. I was rewarded with a very solid performing SSB export radio that I used in my mobile all over the Northwest United States and I took the radio with me when I moved to Hawaii. When I received the radio I did the expanded frequency conversion (which was a little difficult on the older models), added the NPC modification, and turned up the microphone gain via the small potentiometer located inside the microphone. At the time I had purchased one brand new on eBay for $169. It’s hard to believe it’s been seven years since I owned my first amber display Magnum 257. Rather than wasting time re-writing the same info to sound different, I thought I’d focus on writing about what sets this radio apart from the others. Magnum 257HP 10 Meter AM/FM/SSB Export Reviewīefore you begin reading this article I will give a little disclaimer: I did use some of the paragraphs from the Omegaforce and Deltaforce articles in this review since these three radios do share some of the same features.
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