Yaesu 101E Finals

[Rudes]

Hello,
I have read threads that say when replacing the finals on these radios with usa type tubes, before neautralization to change cap 125 from 100pf to 10pf. Is this the cap when looking from the top of the radio down at the finals, runs between the variable cap to the top of the coil located between the 2 tubes? Right now I am seeing about 55 watts on my watt meter dead key on a/m and only 20 watts swing on sideband. Is this normal or are the finals weak? My RCI 2950 shows a swing of 40 watts on ssb.

 

[wavrider]

A wealth of information on yahoo groups Fox Tango 101.

The service manual and all upgrades mods are available for down loads there.

I do not have the service manual in front of me , it went back with the rig when it was finished being aligned.

Yes if you are going to use American made finals the cap does need to be changed.

 

[Rudes]

Is the cap location the one I described and do the power levers seem right?

 

[BJ radionut]

New Finals for FT-101xx

In order to use the "American" variety 6JS6's, a simple modification to the neutralization circuit must be made to the final section of the transceiver.

The modification consists of replacing the fixed value 100 pf 1000 VDC mica capacitor with a 10 pf 1000 VDC mica capacitor. This capacitor, C125, is in series with the 10 pf variable neutralizing capacitor off of the plate circuit.

If this modification has not already been completed on your rig, be sure to use a mica or silver mica of at least 1000 VDC.
Do not substitute a different type, because the heat in the final compartment will change the value, and your tubes will fail prematurely. Also, be very careful to keep all leads short and in exactly the same orientation as the original capacitor.

Before reneutralizing, open the variable neutralizing capacitor all the way to minimum engagement and follow the neutralizing instructions in the manual. While dipping the plate, remember to adjust the neutralizing capacitor for equal value meter reading peaks (IC position) on both sides of the dip when tuning the "Plate" control.

Be Careful remember the voltage in that final cage can be Lethal! NON-CONDUCTIVE tuning stick....I use a ceramic type.
Reprinted from Yaesu-Mod page
All the Best
BJ

 

[Rudes]

Cap Location and Power Question

I am aware of the procedure and thank you for the post...but is the location of c125 the cap I have indicated and does the power output sound right for this rig or does it seem down, my rci puts out more on ssb.

 

[Doc Feelgood]

First of all I would keep the AM carrier at 25 or below, SSB on a good working 101x should be 100-180 or so, 150-165 is about average on a suitable accurate meter.

definitely something not right on that radio, and proper neutralization is critical to both performance, and longevity of the tubes.

From your description, your assumption is correct and that is the cap that needs to be changed out for non-oem tubes.

 

[Rudes]

OK...I don't run the radio in AM mode but when I have it in the tune mode I can see 45 - 50 watts on my swan meter when I turn the carrier up. Is this number low? I picked this radio up on ebay and it had GE tubes in it with the 100pf c125 still in it. I changed the cap to 10pf and neutralization. Being that my SSB is low...20 watts...is it the tubes or someting else?

 

[wavrider]

The driver tube is the one that usually takes a pounding in that rig.

I have not seen more than 120 watts out on ten meters, but that was with OEM tubes and how old are they?

Tubes tested good on the B&K precision tube tester and on the lower bands I was seeing around 150 watts on 80 meters with a peak reading watt meter. Autek WM1 meter.

If the proper alignment is not performed, neutralization, band alignment both TX and RX then it can cause poor performance on TX and RX.

How is the receive on the rig?

What band are you testing power out put on?

Test all bands into a dummy load if you have that available and see if the lower frequencies give you more power out.

 

[Rudes]

Low Power

First let me thank everyone who has replied!
The receive works great. On 10 meters the output power is only 8 watts on ssb but is 80 watts rms on 80 meters. I read in the service manual that a "short" between the white leads from the tank coil could cause a similar problem. Does this sound probable and if so how would I correct it?

 

[Rudes]

Cleaned Band Selector

I cleaned the band selector switches, especially in the trap coil area and got an increase in output. On 10m 40 watts rms from 8 and 140 rms from 80 on 80meters. Sounds like an alignment?

 

[GnG8d]

HERE is the full blown service manual for that rig. If you are seeing 140w pep on 80m, you should be able to see ~100w pep +/- on 10m I would think. But seeing that kind of output on 80m tells me that the tubes aren't all that bad of shape.

 

[Rudes]

Does not seem to be the tubes

Thanks - had the manual. Obviously something needs adjustment. Where should I look next...ALC or TX adjustment?

 

[GnG8d]

If it were me? I'd use the manual and a scope and go through it. I'd probably even replace a lot of those old carbon composite resistors while I was at it. But I'm not seasoned enough so say "go here" after just reading of the symptoms.

 

[wavrider]

If it were me? I'd use the manual and a scope and go through it. I'd probably even replace a lot of those old carbon composite resistors while I was at it. But I'm not seasoned enough so say "go here" after just reading of the symptoms.

X 2 on the above.

Probably a good alignment front to back will bring that rig back to life.

 

[GnG8d]

How'd it go?