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FT-301 - A repair journey begins

 

Hi to all in the group!

I have started to repair an FT-301 that I acquired years ago. Must say I am mightily impressed with how Yaesu built these. Just love the plug-in card system - must surely be a candidate for the easiest radio to get into and fix ever made.

So far, I have it working on receive - and sounding nice. On transmit, and without the booster plugged in on the rear panel, it produces up to 20 W of RF in SSB, but only a disappointing 1 W of RF in CW / FSK / AM. Sadly, the booster has suffered some mechanical damage in that the 'Jones' plug has taken a bash and the paxolin on the rear that retains the pins now doesn't. Might end up having to replace the whole plug.

A couple of questions, if I may:

Q1. Should the impedance of the companion hand microphone be 50 kOhm, or 500 Ohm? I thought I had read somewhere that, like the FT-101 up until the E/F, the microphone should be a Hi-Z type. I have both types here, but the 50 kOhm unit does not drive the '301 TX at all, whereas the 500 Ohm one does with gusto.

Q2. The front panel meter on mine is open circuit. The circuit shows it as a 200 uA FSD unit. Does anyone have experience of taking one apart and making a fix, or am I looking at finding a (unobtanium) replacement?

Regards,

Mark, G4FPH.
 

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H Mark,

Have you adjusted upper and lower sideband frequency. These xtals typically drift out of spec. adjusting the frequency pot will typically not get you there.
If you need parts I have plenty of them.
You’ll need a good spectrum analyzer or sensitive frequency counter to measure xtal freq. Also the SSB filters drift(xtal based). I’ll need to sweep them to see how far of they are.
Verify supply voltages, see schematic for voltages.

Let me know if you need more details.

Michael


On Jan 29, 2024, at 7:52?PM, atlasstuff <g4fph@...> wrote:

?Hi to all in the group!

I have started to repair an FT-301 that I acquired years ago. Must say I am mightily impressed with how Yaesu built these. Just love the plug-in card system - must surely be a candidate for the easiest radio to get into and fix ever made.

So far, I have it working on receive - and sounding nice. On transmit, and without the booster plugged in on the rear panel, it produces up to 20 W of RF in SSB, but only a disappointing 1 W of RF in CW / FSK / AM. Sadly, the booster has suffered some mechanical damage in that the 'Jones' plug has taken a bash and the paxolin on the rear that retains the pins now doesn't. Might end up having to replace the whole plug.

A couple of questions, if I may:

Q1. Should the impedance of the companion hand microphone be 50 kOhm, or 500 Ohm? I thought I had read somewhere that, like the FT-101 up until the E/F, the microphone should be a Hi-Z type. I have both types here, but the 50 kOhm unit does not drive the '301 TX at all, whereas the 500 Ohm one does with gusto.

Q2. The front panel meter on mine is open circuit. The circuit shows it as a 200 uA FSD unit. Does anyone have experience of taking one apart and making a fix, or am I looking at finding a (unobtanium) replacement?

Regards,

Mark, G4FPH.

 

Dear Mark

to question 1
?mic 500 ohm. You can find at page 7 instruction manual ft - 301.

att
Emerson, PP6EW

Em ter., 30 de jan. de 2024 às 00:52, atlasstuff <g4fph@...> escreveu:

Hi to all in the group!

I have started to repair an FT-301 that I acquired years ago. Must say I am mightily impressed with how Yaesu built these. Just love the plug-in card system - must surely be a candidate for the easiest radio to get into and fix ever made.

So far, I have it working on receive - and sounding nice. On transmit, and without the booster plugged in on the rear panel, it produces up to 20 W of RF in SSB, but only a disappointing 1 W of RF in CW / FSK / AM. Sadly, the booster has suffered some mechanical damage in that the 'Jones' plug has taken a bash and the paxolin on the rear that retains the pins now doesn't. Might end up having to replace the whole plug.

A couple of questions, if I may:

Q1. Should the impedance of the companion hand microphone be 50 kOhm, or 500 Ohm? I thought I had read somewhere that, like the FT-101 up until the E/F, the microphone should be a Hi-Z type. I have both types here, but the 50 kOhm unit does not drive the '301 TX at all, whereas the 500 Ohm one does with gusto.

Q2. The front panel meter on mine is open circuit. The circuit shows it as a 200 uA FSD unit. Does anyone have experience of taking one apart and making a fix, or am I looking at finding a (unobtanium) replacement?

Regards,

Mark, G4FPH.

 

Emerson,

Thank you for the reference - I see it now. I will move my 50 kOhm microphone out of the way, so I do not connect it by accident and think that the TX is faulty!

Regards,

Mark, G4FPH.
 

Michael,

Thanks for the reply.

I have not yet adjusted the carrier oscillators. On LSB and USB they sound about right to my ears as is, just listening to band noise and to some stations. I will trace the path for CW to get to the bottom of why RF output is low on TX for that mode.

If you have a booster amplifier that you have broken for spares then I may be back in touch regarding the Japanese 'Jones' plug if I cannot come up with a solution. Likewise the S-meter. Are you in the US?

Regards,

Mark, G4FPH.
 

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Best wishes,

South Hills Amateur Radio Club, Inc.
KS3R / W3PIT / N3WX
, &

January 30, 2024 2:57 PM, "atlasstuff" <g4fph@...> wrote:

Michael,

Thanks for the reply.

I have not yet adjusted the carrier oscillators. On LSB and USB they sound about right to my ears as is, just listening to band noise and to some stations. I will trace the path for CW to get to the bottom of why RF output is low on TX for that mode.

If you have a booster amplifier that you have broken for spares then I may be back in touch regarding the Japanese 'Jones' plug if I cannot come up with a solution. Likewise the S-meter. Are you in the US?

Regards,

Mark, G4FPH.

 

James,

Thanks for the link. I had looked on eBay UK, but not US. Good to know there are replacements out there across the Atlantic.

I'll look to extract the meter from my radio in the coming days. I see it's on a bracket. Would be great if extraction of the meter on the bracket turned out to be as easy as pulling cards!

Regards,

Mark, G4FPH.
 

I took a look at extracting the meter (on it's bracket) from the radio. Sadly, it seems this is not possible without first removing the front panel. That's more work than I want to do at this stage.

On the plus side, I now have the analogue dial '301 working well on RX and TX. I did a major glue job on the thin, SRBP spacer that indexes the pins on the rear of the six-pin 'Tocon' (Miniature Jones-like) connector on the booster. The pin spacing and orientation of the Tocon is not the same as a Jones. I took measurements of the spacer as, if my glue job fails at some point in the future, I will have a go at making a replacement out of some 1.6 mm thick fibreglass board, with slot and hole cutting using a Dremel, or similar.

The '301 produces 100 W+ PEP of SSB on all bands. The stock Yaesu hand mic didn't sound great, so I substituted a Shure 444T and got improved reports. I did have to move the carrier crystals a little to optimise make the best of the (slightly narrow for my tastes for rag-chewing) filter bandwidth. PA bias sounds OK. The RF processor works well - just like I remember the one in my FT-101E. The VFO is incredibly stable.

There's still a way to go fixing up this old rig - the meter; lack of power out on CW; full alignment; making an adaptor so it will key my linear; and possibly more - but I like 'rolling restorations'. What it has shown already is that the results will justify the time spent. When I run out of electronic work to do on it, I might just attempt to give it a fresh coat of paint, something I have never tried.

Regards to all in the group,

Mark, G4FPH.
 

The front panel on the 301 is very easy to remove. Take a pick if you don't have a spare but no surprises in there. Just wrench time.
Dave
 

In Europe they were sold as the Sommer Kamp 301. I probably have a good meter if you can't find one.
Dave
 

This is a problem with the 301. I do have an instruction sheet on how to set the SSB osc's. You would think they would run 1.5 kc of center but there is a problem in the filter board I think. I set them to about 1.2 kc using two different tones back and forth. The manual is almost right on this one. There never was a service manual published as these were lemons that canceled instantly when the WARC bands came out.
Dave
 

Does this mean none of this went through? Can some body help me with this software? Please.
Dave

--
Dave Bohlen

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