Exactly. I'm trying to find something 'fast'. Some of the numbers, when I can find them, are terrible. For reference, is this fast acting?!?

Or these blade style!??

Although the reactance is balanced out, what are the ohms (zero reactance) doing? Some will call ohms; impedance.

The speed of the fuse may be critical to the second fuse. The second fuse? Yes, the printed circuit!

Mick and others,

One additional question. I seem to remember that fuses are not only rated for current and voltage but also speed. There are fast fuses and slow fuses. I'm guessing the SMD one in the rig is a fast one. I'm wondering if an automotive blade style fuse is 'fast enough'. Any thoughts?

Mike / KA4CDN

I measured the voltage on the CAT port rig at the rig's pinout. Under 1v. \

I found the schematic in the file section. File?ft857 technical supplement, part one, page 25, layout A, section A3 has part F1001 located.




Measuring continuity in circuit, it is OPEN.

So I believe you all are right on. Now to summon up the courage along with steady hands and younger eyes!?

Mike / KA4CDN

I used the smaller spade type fuse when I done mine, was a better fit in the 857 case.

Mick SA4MDN

Thanks everyone.

I'll open the 857 later today. Can the fuse be check in circuit?

I'm thinking that I might have a more serious problem because as I mentioned, even supplying the 13.8 to the tuner via its alternate power jack, the radio doesn't indicate that the tuner is there.

I've got a buddy with a FT-857 and I plan on going over there Tuesday to do some simple swap testing so will know more than. With that info, I may call Yaesu and get their advice.

I'll report back.

Mike

https://cdn.shopify.com/s/files/1/0289/7782/3843/files/MFJ-939_Schematic.pdf?v=1586534091

There is a fuse in the circuit that should be checked. F1001 is the number 3.15 amp. This is a chip fuse near the CAT connector.
This should tie into the 13.8 supply.?
I have no good idea why you are measuring 5.04 unless it is being fed back from the MFJ - 939Y. Have you checked the voltage at the connector on the radio?

Maybe this, it shows 897D, but 857D is the same, its what I had to do to my 857D when I popped the cat power fuse when I connected to a wrong tuner.
Also makes changing the fuse if ever needed in the future a breeze.



Mick SA4MDN

Which tuner and how was it blown?

Mike / KA4CDN

Hi. New member here.

I'm using my FT-857D with a MFJ-939 auto tuner. It had been working great since Nov 2019 but yesterday I had a problem where it wasn't tuning.

I'm trying to diagnose the problem. The MFJ-939 is not powering on. It normally gets power from the 857 via the interface cable. It also has an alternate power input. If I supply power to the alternate input, the tuner powers on. However,

Even with the tuner powered on, the 857 screen does not display TUNE. Pressing the TUNE soft button doesn't do anything. I tried doing a complete reset of the 857 (Press HOME and Power On), reset Menu 020 to TUNER and Menu 085 to TUNER. No success.

The MFJ-939 came with the interface cable and it's manual provides the pin out for the tuner side. It indicates that the rig is suppose to supple the 13.8vdc on three of the pins. I'm measuring 5.04vdc.?

This is a mobile install. Yesterday, when I was using the setup, it was near zero degrees F.?

I'm worried that the MFJ has killed some portion of the FT-857D. The fact that I don't see the 13.8vdc seems BAD. And that the rig doesn't seem to know the MFJ-939 is there even when the tuner is ON via alternate power make me wonder if the CAT control is killed too. I don't have a means of testing the CAT independently.

Any advise or suggestions?

Mike / KA4CDN

What about the power settings in the service menu?

The 1/2 inch is between the radio top/bottom and the bracket.?
Buzz
KD4CXI

All,
?Thanks for the reply's and information and yes I did search the Web and found all the major dealers out of stock. Just to be clear this is not a life and or death have to have I made my own mounting bracket that works just fine. I just like to keep things original and complete when it comes to my radio equipment (and most other things as well) So if I run onto a bracket that no one needs or wants that would be great if not Oh well life will go on. By the way Tony VA7TF I only use 1/16 on each side of the radio and the screws fit as they should if i had used a 1/2 inch the screws would not have reached without having to deform (bend out of shape) the bracket. Again thank you all for the reply's. Take care stay safe
73's
ke4ska

开云体育

Did you try calling yaesu?
--
Leonard K. Pennock (AD7AS)

Bad luck. I cannot find new stock. It looks like an appeal on here is the only chance. Maybe someone has a ruined radio and still has the accessories? Good hunting.