Dimming the panel lights on the Yaesu FT-301
No modification on your FT-301 is required!

Designed by sv3ora


Before you attempt any modification on any commercial radio, you should first study it's manual really well. Here is the manual of the Yaesu FT-301 transceiver. It is a great radio, in fact one of the best looking radios ever produced to my taste. To me, when I am in front of the panel of this radio, it feels like being in front of an old military plane cockpit. This alone is an excuse for more time on HF transceiving and DX contacts. I have two of them, both with analogue dials (versions FT-301 and FT-301S), because I do not particularly like the digital readout versions of this radio, the FT-301D and FT-301DS.

This radio has a special panel, as it is totally black with white markings on it. Even the S-meter background is black. This combination of colors gives a very special property to the radio, it provides high contrast. High contrast, allows the reading of the markings even on very dim light conditions in the shack.

The nice looking frequency dial and S-meter, have incandescent bulbs above them to light them up, two for the dial and one for the S-meter. Whereas these are incandescent bulbs and not LEDs, they still shine the dial and S-meter quite brightly. Many of you may think that a brightly shinning dial especially from an incandescent bulb, is beautiful in the night. It certainly has something that the cold light of LEDs cannot reproduce easily, being vintage or simply a different kind of light. However, for this high contrast dial and S-meter, the bright lighting is more of a decoration thing rather than practical.

There are a few points with bright lighting that you might have thought or not. The first point is that a bright incandescent light causes the incandescent bulb to fail after some years of operation, because its filament burns at high temperature near it's nomimal voltage/current level. Indeed, one of the most common problems when you buy vintage radios, is that one or more incandescent bulbs have failed and need to be replaced. Replacing a miniature incandescent bulb nowadays is not the easiest thing as these become more and more rare in this "LED era". They are cheap when they are found though.

The second point is that the FT-301 dial and S-meter are high contrast and the addition of a bright light only makes contrast worse. As I said, it is there mainly for decorative purposes. To test this, I disconnected the bulbs and switched on the radio. The markings on the dial and the S-meter could be read even at very dim light conditions inside the shack. In fact, on low ambient light, reading the dial and S-meter without any background lighting was preffered, not only for contrast reasons, but also because any tiny dust inside these black background dials shows up way more easily, when the bright incandescent lights are on. Ok, cleaning these from time to time should help, but it is not that easy to clean them, as this requires dissasembly of the front panel of the radio, its knobs and in the case of the S-meter, opening it up.

The third point somehow relates to the second. In the frequency dial, there is a dim red vintage LED indicator, which indicates the exact frequency reading. There is a pointer marking there as well for the purpose, but the dim red LED is behind the rotating disc which has the KHz markings on it. The rotating disc is black with white KHz markings on it. When the dim red LED light hits the disc from behind, it's light passes through the white disc markings but not through the black background of the disc. This makes markings appear instantly red and then switched back to white, giving their turn to adjacent markings, when you rotate the frequency knob. Because the KHz markings are close together onto the disc, this LED has to be dim, so as it's light can effectively light up only the current KHz mark and not the adjacent ones. And here begins the problem with the bright background lighting. Such a lighting makes the dim LED pointer barely visible in some ambient light conditions. So once again, the usage of bright dial lights degrades contrast and readability.

There is a fourth point to consider, but this is kind of personal prefference. A bright dial in a dark room makes your brain concentrate more on the light and markings and a bit less on the reveived audio. We are talking about faint signals here, where you try to dig them from the noise. They say the best reception of such signals is being done with the eyes closed, or in a dark room and with headphones on. It seems than when you don't use your eyes a lot, your ears become more sensitive, as your brain focuses more on the hearing sense. It is the same thing when you compare the radio with the television, in TV you use your eyes a lot and stop hearing things around you as your brain focuses on it.

The contrast of the dial and the S-meter in the FT-301 is so nice that I actually prefer reading them without any incandescent light bulbs switched on, when the ambient light conditions in the shack are mid to high. But when all the lights in the shack are switched off, you must have some kind of S-meter and dial lighting, because otherwise only the red LED will be seen. To satisfy this and overcome the problems mentioned in the previous paragraphs, I decided to operate the incandescent bulbs at a lower brightness. This greatly increases their life span, allows the LED indicator to be visible, preserves the high contrast on mid to high ambient lighting and allows for reading of the dial and the S-meter on total darkness, without fancy blinding lights.

There are different solutions for operating the bulbs in lower brightness, current limiting resistors, higher voltage bulbs, voltage regulators etc. However, the one I liked the most was the simplest and the one that did not required any additional components or mods to the radio. I connected the two frequency dial lights in series instead of parallel. This reduced their brightness significantly. My S-meter bulb had already burnt out (the classic problem I described above) so I found one from my junk box, that run at about the same brightness as the series connected dial bulbs. I guess, if the original S-meter bulb had not gone bad, I could connect the two frequency dial bulbs in parallel and these in series with the S-meter bulb, but this was not tested.

The results were very satisfying. Now I can leave the radio on for many hours each day, without worrying too much about burning out the incandescent light bulbs. When there is mid to high ambient lighting, the incatescent bulbs are so dim that their light is not seen onto the dials and only the ambient light lights the dial up and revealrs it's high contrast glory. When the shack lights are switched off, the brightest thing is the dim RED pointer led, indicating nicely (but not blindingly) the KHz on the tuning dial. The even dimmer incandescent light is barely seen from accross the dark room and it provides just enough light to read the markings when being close to the radio with the room lights off, without blinding you up. With the very dim incandescent bulbs, I discovered that the FT-301 transparent plexi glass on the frequency dial, shows a tiny amount of greenish-blueish hue onto some areas near the bulbs, despite the bulbs color is dim orange. I do not know how to explain this, but it is a very nice effect. Perhaps it relates to the tiny coloration of the plexi glass which is not noticeable in bright light. We are talking about traces of greenish-blueish hue here, don't think that they make the plexi glass turn blue! These light variations are so small that cannot be shown in a photograph, as the camera is not sensitive enough to show them, like the eye conceives them.


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