neutralizing new tubes
 

Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)

neutralizing new tubes
 

Will wrote:
Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)


Hi,
Yes you need to neutralize your new final tubes. Do a Google and locate
a copy of the TS520S manual and download it. You will find the
procedure in there. Good luck with your 520, its a great set.

neutralizing new tubes
 

On May 29, 4:31*pm, Robert wrote:
Will wrote:
Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)

Hi,
Yes you need to neutralize your new final tubes. Do a Google and locate
a copy of the TS520S manual and download it. You will find the
procedure in there. Good luck with your 520, its a great set.

The operating manual, which has neutralizing instructions, is
available free from the Kenwood site:
http://www.kenwoodusa.com/Support/AMA_Radios/#_
Scroll down to the "Amateur Radio Manuals" window and select the
model.
Also, download the service bulletins from the window below it.

Richard Knoppow
WB6KBL

neutralizing new tubes
 

On Fri, 29 May 2009, Will wrote:

Date: Fri, 29 May 2009 23:13:33 GMT
From: Will
Newsgroups: rec.radio.amateur.boatanchors
Subject: neutralizing new tubes

Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)

You might ask yourself, first, are the old tubes really weak? i.e. less
to much less than 50 watts of carrier output, as measured with a wattmeter
into a good load (dummy or real).

You might ask yourself, second, what bands you plan on operating on.

If low (160,80,40 meters) you might not need netralization. All the old
handbooks mention that self-oscillation is a problem at the higher
frequencies.

There are two classical methods to test for neutralization (after you put
in the new tubes):

1. With rig output into a dummy load and wattmeter, can you get RF output
with excitation removed, at some setting of grid drive tuned circuit or
plate output tuning.

2. You look at grid drive and sweep the plate tuning through its range: if
the rig is not neutralized, then you'll get a dip or blip in grid drive.

You can't do this directly with the 520 since it does not register grid
drive on the finals. But, you can adjust the drive level knob to at or
near zero output. Then, you fiddle with grid drive tuning knob AND, separately,
plate tuning knob, and if plate current goes up high and RF comes out (as
shown on the watmeter), then you got self-oscillation in the finals. Bad
news. You'll have to adjust the neutralization as per the proceedure.

Many old rigs did not have neutralization. DX-100, Viking Ranger, etc.,
were all 6146 rigs with no neutralization. The Drake twin lines (6BQ6s in
final) did have neutralization. Sometimes they worked, sometimes not. I
had a single 6146 DX-40 transmitter that I discovered went into final
oscillation if I removed grid drive. Bad news. I made my own
neutralization wire from bottom of the chassis to the top and moved it
closer or farther from the plate of the 6146 until the self-oscillation or
grid drive flicker stopped when I tuned the plate circuit. All trial and
error.

Good luck

neutralizing new tubes
 

"Stray Dog" wrote in message
r.org...

On Fri, 29 May 2009, Will wrote:

Date: Fri, 29 May 2009 23:13:33 GMT
From: Will
Newsgroups: rec.radio.amateur.boatanchors
Subject: neutralizing new tubes

Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if
there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)

You might ask yourself, first, are the old tubes really weak? i.e. less
to much less than 50 watts of carrier output, as measured with a wattmeter
into a good load (dummy or real).

You might ask yourself, second, what bands you plan on operating on.

If low (160,80,40 meters) you might not need netralization. All the old
handbooks mention that self-oscillation is a problem at the higher
frequencies.

There are two classical methods to test for neutralization (after you put
in the new tubes):

1. With rig output into a dummy load and wattmeter, can you get RF output
with excitation removed, at some setting of grid drive tuned circuit or
plate output tuning.

2. You look at grid drive and sweep the plate tuning through its range: if
the rig is not neutralized, then you'll get a dip or blip in grid drive.

You can't do this directly with the 520 since it does not register grid
drive on the finals. But, you can adjust the drive level knob to at or
near zero output. Then, you fiddle with grid drive tuning knob AND,
separately, plate tuning knob, and if plate current goes up high and RF
comes out (as shown on the watmeter), then you got self-oscillation in the
finals. Bad news. You'll have to adjust the neutralization as per the
proceedure.

Many old rigs did not have neutralization. DX-100, Viking Ranger, etc.,
were all 6146 rigs with no neutralization. The Drake twin lines (6BQ6s in
final) did have neutralization. Sometimes they worked, sometimes not. I
had a single 6146 DX-40 transmitter that I discovered went into final
oscillation if I removed grid drive. Bad news. I made my own
neutralization wire from bottom of the chassis to the top and moved it
closer or farther from the plate of the 6146 until the self-oscillation or
grid drive flicker stopped when I tuned the plate circuit. All trial and
error.

Good luck

Thanks for your input and everyone elses replies. I did a google search and
came up with this URL http://www.k4eaa.com/faq.htm

It was extremely helpful and it gave me a better idea of what I need to get
back on the air. Problem now is I don't own a dummy load or RF
millivoltmeter so til then I guess I'll be off the air . This sux.

neutralizing new tubes
 

Will wrote:


Thanks for your input and everyone elses replies. I did a google search and
came up with this URL http://www.k4eaa.com/faq.htm

It was extremely helpful and it gave me a better idea of what I need to get
back on the air. Problem now is I don't own a dummy load or RF
millivoltmeter so til then I guess I'll be off the air . This sux.



I do it the poor man's way. Watch an output meter and the plate current
meter simultaneously. Key down and see if the dip on the plate
corresponds with max output.

If not, budge the neut. cap slightly and repeat again. Keep the drive
down so that you don't screw up a new set of tubes.

-Bill

neutralizing new tubes
 

On Tue, 2 Jun 2009, Will wrote:

Date: Tue, 02 Jun 2009 22:01:52 GMT
From: Will
Newsgroups: rec.radio.amateur.boatanchors
Subject: neutralizing new tubes


"Stray Dog" wrote in message
r.org...

On Fri, 29 May 2009, Will wrote:

Date: Fri, 29 May 2009 23:13:33 GMT
From: Will
Newsgroups: rec.radio.amateur.boatanchors
Subject: neutralizing new tubes

Hi all ,
I am replacing the 7146's on my Kenwood 520s and would like to know if
there
is a certain proceduere I need to go through to neutralize the tubes for
optimum performance and maximum life.Thanks in advance .

PS I'm kinda new at this so be gentle :)

You might ask yourself, first, are the old tubes really weak? i.e. less
to much less than 50 watts of carrier output, as measured with a wattmeter
into a good load (dummy or real).

You might ask yourself, second, what bands you plan on operating on.

If low (160,80,40 meters) you might not need netralization. All the old
handbooks mention that self-oscillation is a problem at the higher
frequencies.

There are two classical methods to test for neutralization (after you put
in the new tubes):

1. With rig output into a dummy load and wattmeter, can you get RF output
with excitation removed, at some setting of grid drive tuned circuit or
plate output tuning.

2. You look at grid drive and sweep the plate tuning through its range: if
the rig is not neutralized, then you'll get a dip or blip in grid drive.

You can't do this directly with the 520 since it does not register grid
drive on the finals. But, you can adjust the drive level knob to at or
near zero output. Then, you fiddle with grid drive tuning knob AND,
separately, plate tuning knob, and if plate current goes up high and RF
comes out (as shown on the watmeter), then you got self-oscillation in the
finals. Bad news. You'll have to adjust the neutralization as per the
proceedure.

Many old rigs did not have neutralization. DX-100, Viking Ranger, etc.,
were all 6146 rigs with no neutralization. The Drake twin lines (6BQ6s in
final) did have neutralization. Sometimes they worked, sometimes not. I
had a single 6146 DX-40 transmitter that I discovered went into final
oscillation if I removed grid drive. Bad news. I made my own
neutralization wire from bottom of the chassis to the top and moved it
closer or farther from the plate of the 6146 until the self-oscillation or
grid drive flicker stopped when I tuned the plate circuit. All trial and
error.

Good luck

Thanks for your input and everyone elses replies. I did a google search and
came up with this URL http://www.k4eaa.com/faq.htm

It was extremely helpful and it gave me a better idea of what I need to get
back on the air. Problem now is I don't own a dummy load or RF
millivoltmeter so til then I guess I'll be off the air . This sux.




Try a plain 100 watt incandescent light bulb.