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FT-101e Neutralization question



 
 
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  #1  
Old January 20th 04, 02:02 AM
gil
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Default FT-101e Neutralization question

Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw
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  #2  
Old January 20th 04, 02:47 AM
Edward Knobloch
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Default

In order to neutralize, you must first open the screen voltage
supply to the 6146's. This may require unsoldering the screen
grid supply at the 6146 sockets (pin 3 of each 6146 octal socket).
Leave the the tubes in their sockets, with plate
connectors attached. On the 10m band, feed some power to the grids
of the finals, and measure the output signal on the coax (50 Ohm load).
You can use a separate, loosely coupled receiver tuned to the frequency
for this purpose. (I.e., use a short antenna wire placed near
the output coax, connected to the separate receiver.)

Adjust the grid tune, plate tune and plate load capacitors
for maximum output signal, then adjust the neutralization capacitor
for minimum signal. There should be a point of the neutralization
adjustment where the output signal has a definite minimum.
Congratulations - you are now neutralized.

Be careful - you are working near lethal voltages, and you should use a
insulated, non-metalic tool to adjust the neutralization capacitor.

Keep one hand in your pocket when you reach into the transceiver,
so you won't get high voltage across your chest. If you don't +know+
what you are doing, ask another ham to help. Don't be alone
in the house when you are reaching around the 800VDC.

Both final tubes should be the same type. It is not good practice
to mix a 6146 or 6146A and a 6146B.

73,
Ed Knobloch

gil wrote:

Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw


  #3  
Old January 20th 04, 02:49 AM
Gary Schafer
Guest
 
Posts: n/a
Default

Adjust it so that the plate current dip occurs at exactly the same
point that you get maximum output while you tune the plate tuning
control.

73
Gary K4FMX


On Tue, 20 Jan 2004 01:02:55 GMT, "gil"
wrote:

Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw


  #4  
Old January 20th 04, 05:39 AM
SAM
Guest
 
Posts: n/a
Default

The 101E uses 6JS6s, not 6146s. Check and see if they are American tubes or
original Toshiba. Most of the original ones had a green stripe around them,
but the white letter Toshibas will work just fine. If they are Toshibas you
should not have a problem neutralizing them unless one or both of the tubes are
bad. If they are American tubes, you will need to change C125, the 100 pF
mylar block cap (that is in line with the tunable neutralization cap) to 10 to
15 pF. Then try neutralization.

Good luck!
  #5  
Old January 20th 04, 06:39 AM
Bob W7AVK
Guest
 
Posts: n/a
Default

Edward - Agree completely with your procedure to neutralize the FT-101E. Should
work fine. But doesn't the FT-101E have a pair of 6JSC6 in its final? Might have
told the poor fellow there is a difference between the original supplied JA
version of the tubes and anything that might be obtain here in the states. That
to run RCA or local brand tubes you need to change to small series fixed cap in
the neutralize circuit. Can't remember which way or how much its changed. But
this is important for with out the change the small neutralization cap doesn't
have enough range to do the job..

Good luck,

73 Bob W7AVK

Edward Knobloch wrote:

In order to neutralize, you must first open the screen voltage
supply to the 6146's. This may require unsoldering the screen
grid supply at the 6146 sockets (pin 3 of each 6146 octal socket).
Leave the the tubes in their sockets, with plate
connectors attached. On the 10m band, feed some power to the grids
of the finals, and measure the output signal on the coax (50 Ohm load).
You can use a separate, loosely coupled receiver tuned to the frequency
for this purpose. (I.e., use a short antenna wire placed near
the output coax, connected to the separate receiver.)

Adjust the grid tune, plate tune and plate load capacitors
for maximum output signal, then adjust the neutralization capacitor
for minimum signal. There should be a point of the neutralization
adjustment where the output signal has a definite minimum.
Congratulations - you are now neutralized.

Be careful - you are working near lethal voltages, and you should use a
insulated, non-metalic tool to adjust the neutralization capacitor.

Keep one hand in your pocket when you reach into the transceiver,
so you won't get high voltage across your chest. If you don't +know+
what you are doing, ask another ham to help. Don't be alone
in the house when you are reaching around the 800VDC.

Both final tubes should be the same type. It is not good practice
to mix a 6146 or 6146A and a 6146B.

73,
Ed Knobloch

gil wrote:

Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw


  #6  
Old January 21st 04, 12:17 AM
gil
Guest
 
Posts: n/a
Default

Yes, The 101E uses 6JS6s, not 6146s, but I get the point.
I guess what I should be looking for is to get the minimum RF out by turning
the cap and finding the spot right about the middle...that's where I have it
set now and seems to work real smooth.

Thanks all for the help!

Gil

Remove NOSPAM to reply

"gil" wrote in message
ink.net...
Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can

do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on

the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into

oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw
--
Remove NOSPAM to reply




  #7  
Old January 21st 04, 02:37 AM
Gary Schafer
Guest
 
Posts: n/a
Default

Gil,

You don't need to disconnect any voltages to neutralize the finals.
You can easily check to see if you have it properly neutralized by
doing what I said in my last post.

Tune up as normal. Then watch your plate current while you turn the
plate tuning control back and forth. You should get maximum power out
at exactly the minimum plate current. (plate current dip) If these two
things do not occur at the same point then adjust the neutralizing
capacitor slightly and check again. It is not hard to do.
This method is much easier than disconnecting voltages.

By the way do this on the 10 meter band.

73
Gary K4FMX


On Tue, 20 Jan 2004 23:17:32 GMT, "gil"
wrote:

Yes, The 101E uses 6JS6s, not 6146s, but I get the point.
I guess what I should be looking for is to get the minimum RF out by turning
the cap and finding the spot right about the middle...that's where I have it
set now and seems to work real smooth.

Thanks all for the help!

Gil

Remove NOSPAM to reply

"gil" wrote in message
link.net...
Just recently got a Yaesu ft-101e that needed some alignment and the only
thing I cant seem to get "accurate" is the neutralization, the best I can

do
is to rotate the adjustable plate capacitor till I get the lowest output
reading on the power meter, which range from 50 to 80 watts depending on

the
band and it seems to put out a clean signal this way.
Trying to get a higher output reading only sends the finals into

oscillation
with lots of hum and a somewhat "dirty" signal.
Am I on the right trak here or should I do something different?
Any info appreciated....thanks

Gil n2wjw
--
Remove NOSPAM to reply




 




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