Hi all,

I've had an FT-301 for a couple of years, waiting for restoration. Finally got it on the bench and have been working thru the issues. I thought I'd share information about the biggest issue, which I've just solved. The radio was receiving pretty well, but not putting out as much as a milliwatt. I discovered that the PA brick is fine, and couldn't see any issues with the 10 watt amp either.?After some probing with a voltmeter I realized that there was no Switched Tx 13.8v. So started tracing that circuit, and soon enough found that L2, a 35 uH choke connected to one of the feed-thru capacitors on the underside of the rig, was open.

I replaced L2 with a similar value inductor (with a diode "backwards" across it), and immediately on keying up I was startled by a small explosion and smoke!! A tiny black component going from the downstream side of the choke to ground had fried. Whatever it was, it wasn't in the schematic as far as I could tell. But then I noticed an identical part on the other side of the choke, again going to ground. This one was labeled as "6.8 20v", so a capacitor. Not a form factor I'd ever seen before, but perhaps an early version of a tantalum? (small, black, rectangular shape)? Old tantalums are known for "exciting" fireworks on occasion.

Anyway, I replaced both with 6.8 uF electrolytics even though, as I mentioned earlier, I could not find them in the schematic. Clearly they, along with the 35 uH choke, are designed to keep RF out of the Switched 13.8v Tx line. After that I powered up the radio again, and it now puts out a solid 90-110 watts, depending on band.

I've already replaced all electrolytics in the radio, tightened every screw, have cleaned the card-edge connectors and of course also the case and knobs got a good scrub. Before doing a full alignment my next chore is to do something with the dial and S meter lamps. I find them woefully ... BLAH !! I'm not sure how else to describe it, but they just do not do the radio any justice. I'm going to put in LED's, and may mess around a bit to find some sort of (slight) color filter to give them a bit more "pizzazz." Any suggestions?

Joel, VE6EI

I rotated the band selector may times on the 80 meter position and now it is drawing 5 amps so now I am getting some output. I guess I better try to clean the contacts on the band selector.

Next is the carrier balance.? VR501 will not null out the carrier. It almost gets it but no null.?

Switching from CW to USB or AM, The rig momentarily goes into transmit. I guess, a good inspection and

contact cleaning is in order. The rig does not have a CW filter so I ordered one. Found a good deal for a new
Inrad 250 hz filter for 39 bucks on ebay. Last of the few from the manufacturer.

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I would first check DRIVER output just disconnect the PWR AMP input BNCs on the back.
If driver making 5-10 watts out, then problem is PWR AMP LPF or band SW wafer switches.

I have no output on 80 meters, all other bands are ok.
Where do i start to troubleshoot this problem?? I can hear output on a external receiver.
Thanks !!
Robert KH2BR

I replaced that relay but still nothing it keeps on doing that. I replaced the caps and the diode as well. It doesn't war to work for me.?

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The vox is completly down. I tryd dummy load and an dipole antena it doesnt change unfortunatly. I can put the trive switch whaerever i want its still the same unfortunately

Good day
Im a new yaesu ft-301 user. I have a real head scratcher. My yaesu ft-301 works fine until you press the ptt key then its like it stays in tx mode and the sound output does not return to normal. If it does that you need to power down the radio and power it up agen. If anyone can give me a litil bit of inside why it does that it will be much appreciated.

73
ZS6LVJ

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Possible VOX settings/circuit problems?

Ok Mel….it looks like the voltage applied to the relay to change it over night be dropping as the relay changes over….a poke about with your test meter might prove this …..then it may be a matter of looking for the reason for the voltage dropping.
perhaps a short or something ?drawing too much current in the TX . May need you to disconnect the Power rail at various points to isolate that which has failed or is drawing too much current.
long distance fault finding is not easy! Hope that has given you some ideas.

顿补惫别…骋4顿础齿

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When I push to talk.

Does the chattering happen when you just power up the rig, or is it when you press the push to talk.
顿补惫别….骋4顿础齿.

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As Dave points out the CW OSC is on the IF board. Make sure DRIVE control is fully CW and measure pin 3 on the IF board in CW MODE.This enables CW from the MODE switch. If not there, MODE SW contacts might be at fault.

Well thanks to the help received on here, my bargan price 301S is compleatly aligned and is up and running. Now I shall have to think about a paint job for the case, but I have had 2 QSOs on it with compliments about the audio quality.
Thanks folks.
顿补惫别….骋4顿础齿