On Nov 16, 2006, at 1:30 PM, Robert B. Bonner wrote:

Below,

-----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of R L Measures
Sent: Thursday, November 16, 2006 2:48 PM
To: ham_amplifiers@...
Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in

On Nov 16, 2006, at 11:06 AM, Robert B. Bonner wrote:

RL,

Because he adjusted the BIAS to make the 400-500 ma of resting plate
current.

You have to very closely read his message. There's a very slight
language
barrier.

I wondered about that problem after I clicked Send. However, if the
tubes will draw 500mA, there can not be a lack of emission provided
they do that briefly at 0 grid volts.

**** Yes exactly, the emission seems good by rocking the bias. Have to be
careful here as 400ma is 800 watts dissipation. But if it was just a quick
check...

I'm hoping he's not going all the way to zero control grid volts,

To check emission capability for Class AB1 operation, one must (very briefly) measure the anode-I at 0 grid volts.

I'm sure
he's just moving it a bit.

That's why I figured the issue is alignment and driver power. Or possibly
some other issue not finals related. We'll have to wait for his response to
the questions.

That's why I'm wondering a couple things. Curious what tubes were
in the
transmitter previously... and if the unit makes full power with a
different
set of tubes.

I'm thinking these 4CX250's are quite possibly just being
difficult. It
doesn't take much to detune the driver tuning and lose drive. I'm

not

familiar with the durability of Chinese 4CX250's in storage, but
the Eimac
ones are like concrete. Seems you can pull an Eimac one out of the
soup and
crank it up any day of the week.

I've seen a number of Eimac pulls that were kaput.

****I was referring to new old stock 4CX250's the 20 year old ones or more,
they just seem to keep right on ticking no matter where you get them from if
new. Pulls are always a crap shoot.

I just had a beautiful 1 YO 3CPX1500A7 test bad last night. Obviously a
hammered cathode as it drew no plate current, made no grid current or RF.
But the filament warmed up nicely. This one was a new tube placed in an MRI
and it faulted... Obviously the fault was a violent one. Really too bad, I
was getting emotionally attached to that tube, now I need to send it back to
the guy. I had thought I had a great purchase there.

Do you have access to a high-potential tester?

I had a new low hours 8877 back in 1980 do the same thing without a fault.
There was a time that Eimac had issues with quality on the 8877, a weld came
loose INSIDE the tube separating the cathode from the pins.

Did you autopsy the tube, or did you base this diagnosis on ohmmeter measurements?

Just after turning it on when keyed my 77SX went to half resting current.
This was my amplifier and I just about lost it. I worked for a medium sized
Eimac dealer at the time. I talked directly first to Eimac, then ETO and
since that tube was within warranty I went through all the standard return
paperwork. They tore the tube apart and in fact it was the warrantable
quality failure problem and they sent me a new tube.

What failed?

The KWS-1 is a persnickety device in the first place, but once
lined up they
work well.

... and the audio quality is superb.

**** Yes for an early SSB rig they were great.

They were better than later Collins transmitters because they used a 2.7KHz mechanical filter -- i. e., one that was wide enough to pass a humanoid male voice with minimal loss of lows. Later Collins transmitters used a 2.4KHz filter, which is wide enough for female voices but not male voices other than those like that of Verne Troyer, a.k.a. "Mini Me" of Austin Powers movie fame.

I'm more of a KW-1 fan only
because they were total brutes. I'm sure you agree.

I am not a fan of AM because it's a watt-waster and most of the Hams who run AM are lock-to-talk time-wasters.

I think the Collins
engineers sort of let us down a little by not putting bigger tubes in them
from the start.

Agreed, Bob, but in those days the choices were few between the 7580/4cx250R and the 8170.

They of course wanted a transmitter to match the 75A-4 but
still. The 4X150 was a sexy little tube.

Six of them in parallel would have been about right for the then legal 1000w DC indicated input on SSB.
...
R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

开云体育

Below,

Greetings all:

I am looking for a Heath Warrior that has been mostly trashed out. Mainly I need chassis parts. Funds are limited.

73,
Mike, W5UC

Greetings all:

I am looking for a Heath Warrior that has been mostly trashed out. Mainly I need chassis parts. Funds are limited.

73,
Mike, W5UC

Greetings all:

I am looking for a Heath Warrior that has been mostly trashed out. Mainly I need chassis parts. Funds are limited.

73,
Mike, W5UC

Because he adjusted the BIAS to make the 400-500 ma of resting plate
current.

You have to very closely read his message. There's a very slight language
barrier.

That's why I'm wondering a couple things. Curious what tubes were in the
transmitter previously... and if the unit makes full power with a different
set of tubes.

I'm thinking these 4CX250's are quite possibly just being difficult. It
doesn't take much to detune the driver tuning and lose drive. I'm not
familiar with the durability of Chinese 4CX250's in storage, but the Eimac
ones are like concrete. Seems you can pull an Eimac one out of the soup and
crank it up any day of the week.

The KWS-1 is a persnickety device in the first place, but once lined up they
work well.

I don't necessarily recommend going after it with a diddle stick without
knowing more about it working with other tubes and the unit's condition.

BOB DD

On Nov 16, 2006, at 11:06 AM, Robert B. Bonner wrote:

RL,

Because he adjusted the BIAS to make the 400-500 ma of resting plate
current.

You have to very closely read his message. There's a very slight language
barrier.

I wondered about that problem after I clicked Send. However, if the tubes will draw 500mA, there can not be a lack of emission provided they do that briefly at 0 grid volts.

That's why I'm wondering a couple things. Curious what tubes were in the
transmitter previously... and if the unit makes full power with a different
set of tubes.

I'm thinking these 4CX250's are quite possibly just being difficult. It
doesn't take much to detune the driver tuning and lose drive. I'm not
familiar with the durability of Chinese 4CX250's in storage, but the Eimac
ones are like concrete. Seems you can pull an Eimac one out of the soup and
crank it up any day of the week.

I've seen a number of Eimac pulls that were kaput.

The KWS-1 is a persnickety device in the first place, but once lined up they
work well.

... and the audio quality is superb.

cheers, Bob.
...
R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

RL,

Because he adjusted the BIAS to make the 400-500 ma of resting plate
current.

You have to very closely read his message. There's a very slight language
barrier.

That's why I'm wondering a couple things. Curious what tubes were in the
transmitter previously... and if the unit makes full power with a different
set of tubes.

I'm thinking these 4CX250's are quite possibly just being difficult. It
doesn't take much to detune the driver tuning and lose drive. I'm not
familiar with the durability of Chinese 4CX250's in storage, but the Eimac
ones are like concrete. Seems you can pull an Eimac one out of the soup and
crank it up any day of the week.

The KWS-1 is a persnickety device in the first place, but once lined up they
work well.

I don't necessarily recommend going after it with a diddle stick without
knowing more about it working with other tubes and the unit's condition.

BOB DD

On Nov 16, 2006, at 9:26 AM, Robert B. Bonner wrote:

Hsu,

200 watts out, it sounds like he is not getting adequate RF drive to the
finals.

So why is there 500mA of anode-I?

Its been a long time since I've tuned up a KWS-1. The ones I
worked on (back in the 70's) were both 4X150 powered units, not 4CX250.

Does the unit make a KW with another set of tubes in it?

It sounds like with adjusting the bias you can draw current with the tubes.
But if the transmitter doesn't make RF drive it cant make output.

Could just be an alignment issue with the tube change. I don't have a
manual for that transmitter here.

BOB DD

-----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of R L Measures
Sent: Thursday, November 16, 2006 3:32 AM
To: ham_amplifiers@...
Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in

My guess is that the wattmeter is in error.

On Nov 15, 2006, at 4:58 PM, Hsu wrote:

Screen PS V=350V,
anode PS V=2kV.
they are in Collins KWS-1.
My friend have been burn in for 2 hours, the bias crrrent has
ben increase to 100ma, and can get more
(400-500ma) current, I think the tubes are good.
Hsu
----- Original Message -----
From: R L Measures
To: ham_amplifiers@...
Sent: Tuesday, November 14, 2006 2:20 AM
Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in

What is the screen PS V?
What is the anode PS V?

What Class?

On Nov 13, 2006, at 7:34 AM, Hsu wrote:

Hi, There are two Chinese FU-251F(4CX250B) cermic-metal tubes,

they

are new but storge for very long time. The output power only
200-250W( a pair), Could someone cal tell me how to solve this
problem?Is it means I have to drop them in the junk box?
73! Hsu

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

Yahoo! Groups Links

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

Hsu,

200 watts out, it sounds like he is not getting adequate RF drive to the
finals. Its been a long time since I've tuned up a KWS-1. The ones I
worked on (back in the 70's) were both 4X150 powered units, not 4CX250.

Does the unit make a KW with another set of tubes in it?

It sounds like with adjusting the bias you can draw current with the tubes.
But if the transmitter doesn't make RF drive it cant make output.

Could just be an alignment issue with the tube change. I don't have a
manual for that transmitter here.

BOB DD

On Nov 15, 2006, at 5:54 PM, craxd wrote:

It's a possibility that the reason the plate choke did what it did
was over the amp being ran at a frequency where the choke would have
went self resonant.

Does the choke exhibit a self-resonance c. 95MHz when it is in place?

If it looked like someone had been playing around
with the tank coil taps, that could have been what happened. You may
be able to remove a few turns from the top and save it. Use a dip
meter to see what its self resonant frequency is, and that it's not
in the operating bands of the amp.

I would check the complete meter circuit out and add the
modifications Rich mentioned.

Best,

Will

--- In ham_amplifiers@..., jmltinc@... wrote:

OK, I need professional help.

I got a basket-case Henry 3K Ultra some time ago and have been

repairing in

my spare time. Amongst the defects it had, was a plate choke flash-

over. This

took out the .5 ohm (20 watt?) resistor and diode (on the power

supply) that

hold the B- to near ground potential. It also took out a small

(.1?) cap at the

plate current meter (in the desk console). The schematic is not

correct for

this unit and Henry was no help. I did what I think is correct.

Now my problem:

The grid meter show excessive current. I am convinced this is not

"grid

current", but plate current. See the table below for results:

Grid Current Plate Current Power

Out

Amp on, not keyed: 75ma 0ma 0W
Amp keyed, no drive 225ma 150ma 0W
Amp keyed, 50W drive >1,000ma 875ma 1,500W

Notice grid current w/ no excitation and how the grid current

follows the

plate current. Hmmm...

If I draw out how the metering is wired it looks right. For the

grid meter,

here is a .5 ohm resistor shunt from ground to cathode with a 470

ohm, 3 Watt

series dropping resistor from the cathode side of the shunt to the

grid meter.

(The other side of the meter is grounded).

For the plate meter, there are two series .1 ohm shunt resistors

from the

glitch R to the cathode. The meter is connected across this with a

150 ohm series

dropping resistor between it and the shunt R / glitch R connection.

Any ideas?

Thanks
-John

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

My guess is that the wattmeter is in error.

On Nov 15, 2006, at 4:58 PM, Hsu wrote:

Screen PS V=350V,
anode PS V=2kV.
they are in Collins KWS-1.
My friend have been burn in for 2 hours, the bias crrrent has ben increase to 100ma, and can get more
(400-500ma) current, I think the tubes are good.
Hsu
----- Original Message -----
From: R L Measures
To: ham_amplifiers@...
Sent: Tuesday, November 14, 2006 2:20 AM
Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in

What is the screen PS V?
What is the anode PS V?

What Class?

On Nov 13, 2006, at 7:34 AM, Hsu wrote:

Hi, There are two Chinese FU-251F(4CX250B) cermic-metal tubes, they
are new but storge for very long time. The output power only
200-250W( a pair), Could someone cal tell me how to solve this
problem?Is it means I have to drop them in the junk box?
73! Hsu

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

It's a possibility that the reason the plate choke did what it did
was over the amp being ran at a frequency where the choke would have
went self resonant. If it looked like someone had been playing around
with the tank coil taps, that could have been what happened. You may
be able to remove a few turns from the top and save it. Use a dip
meter to see what its self resonant frequency is, and that it's not
in the operating bands of the amp.

I would check the complete meter circuit out and add the
modifications Rich mentioned.

Best,

Will


--- In ham_amplifiers@..., jmltinc@... wrote:

OK, I need professional help.

I got a basket-case Henry 3K Ultra some time ago and have been

repairing in

my spare time. Amongst the defects it had, was a plate choke flash-

over. This

took out the .5 ohm (20 watt?) resistor and diode (on the power

supply) that

hold the B- to near ground potential. It also took out a small

(.1?) cap at the

plate current meter (in the desk console). The schematic is not

correct for

this unit and Henry was no help. I did what I think is correct.

Now my problem:

The grid meter show excessive current. I am convinced this is not

"grid

current", but plate current. See the table below for results:

Grid Current Plate Current Power

Out

Amp on, not keyed: 75ma 0ma 0W
Amp keyed, no drive 225ma 150ma 0W
Amp keyed, 50W drive >1,000ma 875ma 1,500W

Notice grid current w/ no excitation and how the grid current

follows the

plate current. Hmmm...

If I draw out how the metering is wired it looks right. For the

grid meter,

here is a .5 ohm resistor shunt from ground to cathode with a 470

ohm, 3 Watt

series dropping resistor from the cathode side of the shunt to the

grid meter.

(The other side of the meter is grounded).

For the plate meter, there are two series .1 ohm shunt resistors

from the

glitch R to the cathode. The meter is connected across this with a

150 ohm series

dropping resistor between it and the shunt R / glitch R connection.

Any ideas?

Thanks
-John

开云体育

--- In ham_amplifiers@..., jmltinc@... wrote:

OK, I need professional help.

I got a basket-case Henry 3K Ultra some time ago and have been

repairing in

my spare time. Amongst the defects it had, was a plate choke flash-

over. This

took out the .5 ohm (20 watt?) resistor and diode (on the power

supply) that

hold the B- to near ground potential. It also took out a small

(.1?) cap at the

plate current meter (in the desk console). The schematic is not

correct for

this unit and Henry was no help. I did what I think is correct.

#### Whoa. I'll be damned if I can find my henry 3k/8k ultra
manual. IF u had a flash over between plate choke and
chassis.... it would short out the undersized safety diode
between chassis and B- When that happens, the neg of the
grid shunt is now directly in parallel [via the chassis, and then
the shorted safety diode] with the neg of the plate meter.
The pos of the plate meter is normally directly tied to the pos
of the grid meter. You now have a condition, whereby both meter's
are in parallel..... so the grid meter will now read plate current!

### Now u know why I always install a HV fuse in the B+ lead !
You may well have damaged some diodes in the FWB diode assy too...
[waiting for the slo breaker in the 240 v line to open up].

### Henry, in their infinite wisdom, installed the glitch R in
the B- lead.... not a smart move... since that will allow the fil
xfmr to spike to full anode v, etc.

### IF u want to fix this right.... I'd install a 50 ohm-50w
wire wound in the B+ lead. [or at least a 25 ohm-25 watt, wirre
wound] I'd also install a HV fuse just PRIOR to the glitch.
reason is... if glitch R ever exploded.. and pieces of it hung
down and touched chassis.... you want the HV fuse to be on the
inboard side of the glitch R.... so it will blow open.. shutting
every thing down.

### I'd also install some RVS connected diodes, either 6A10 [1
kv -6A]... or PARALLELED 1N5408's [1 kv- 3A] between chassis,
and B- and also some more RVS connected diodes across
BOTH meter's movements. Myself, I use 3 x paralleled 6A10's in
each direction..... 6 in total.... 1200A surge.[between chassis
and B-].... and just 2 paralleled diodes, in each direction, RVS
connected... across EACH meter. The surge rating on the diodes
should be plenty high enough so they never get stressed... and never
short out.... and never have to be replaced. .... then u wouldn't be
having this problem in the 1st place. [Ameritron does the same
thing with their one and only underated safety diode between
chassis and B-..... "check to see if diode XXX is shorted"... IMO,
they shoulda just sized the safety diodes right the 1st time...
since they are dirt cheap]

### The kicker here is....IF u blow any HV fuse.... ur grid
current is gonna go sky high..... so now u need a simple FAST
grid fuse, 3agc type..... wired between chassis.. and grid
shunt. [both the 3k + 8k have NO grid overcurrent protection at
all]

### If u want.... install a 3agc- CATHODE fuse in the CT of the
fil xfmr... either just b4, or just after the bias diodes [used
for setting ZSAC] . Install a 100 k, or better yet.. a pair of
100 k MOF 2-3 watt resistors across the cathode 3agc fuse
holder. Any Cathode fast fuse has to handle the SUM of normal
anode current PLUS grid current.

### when config like this..... if u remove [or blow open] either
the grid fuse... OR the cathode fuse... INPUT swr will rise to
infinity..... shutting down ur xcvr.

### You may well have to get in their.. and draw out the existing
circuit by hand.... then compare it to a standard config. I'll
look for my 3 k ultra manual later on... had it in a binder.

### also... in the combo 3k/8k manual [pretty sure the 3k ultra is
the same setup], Henry used a 2x piece plate choke setup.... I have
the RFC's from the 8 k ultra. The big one is 24 ga magnet
wire , wound on a 1" diam solid teflon rod... and measures 180
uh. The small one is just 20 uh, wound with 18 ga wire. The
large choke was shorted out on the high bands,14-30 mhz...with a HV
solenoid relay.

### You are gonna have to find the reason for the flash over... it
might be the large choke shorting relay.... it might also be the
paralleled bypass caps at the base of the large plate choke, which
on the 8k are 2-3 x 4700 pf caps + 2-3 500 pf doorknobs.


## The amp works as is.. with 1500w out. So this is just a
metering problem.. cuzed by a shorted diode.... caused by a HV arc
to chassis...... which if the amp was config correctly.... should
have just taken out the HV fuse... then the grid fuse a split
2nd later.

Later.... Jim VE7RF

Now my problem:

The grid meter show excessive current. I am convinced this is

not "grid

current", but plate current. See the table below for results:

Grid Current Plate Current Power

Out

Amp on, not keyed: 75ma 0ma 0W
Amp keyed, no drive 225ma 150ma 0W
Amp keyed, 50W drive >1,000ma 875ma 1,500W

Notice grid current w/ no excitation and how the grid current

follows the

plate current. Hmmm...

If I draw out how the metering is wired it looks right. For the

grid meter,

here is a .5 ohm resistor shunt from ground to cathode with a 470

ohm, 3 Watt

series dropping resistor from the cathode side of the shunt to the

grid meter.

(The other side of the meter is grounded).

For the plate meter, there are two series .1 ohm shunt resistors

from the

glitch R to the cathode. The meter is connected across this with a

150 ohm series

dropping resistor between it and the shunt R / glitch R connection.

Any ideas?

Thanks
-John

On Nov 14, 2006, at 6:04 PM, jmltinc@... wrote:

OK, I need professional help.

I got a basket-case Henry 3K Ultra some time ago and have been repairing in
my spare time. Amongst the defects it had, was a plate choke flash- over. This
took out the .5 ohm (20 watt?) resistor and diode (on the power supply) that
hold the B- to near ground potential. It also took out a small (. 1?) cap at the
plate current meter (in the desk console). The schematic is not correct for
this unit and Henry was no help. I did what I think is correct.

Now my problem:

The grid meter show excessive current. I am convinced this is not "grid
current", but plate current. See the table below for results:

Grid Current Plate Current Power Out

Amp on, not keyed: 75ma 0ma 0W
Amp keyed, no drive 225ma 150ma 0W
Amp keyed, 50W drive >1,000ma 875ma 1,500W

Notice grid current w/ no excitation and how the grid current follows the
plate current. Hmmm...

If I draw out how the metering is wired it looks right. For the grid meter,
here is a .5 ohm resistor shunt from ground to cathode with a 470 ohm, 3 Watt
series dropping resistor from the cathode side of the shunt to the grid meter.
(The other side of the meter is grounded).

For the plate meter, there are two series .1 ohm shunt resistors from the
glitch R to the cathode. The meter is connected across this with a 150 ohm series
dropping resistor between it and the shunt R / glitch R connection.

Any ideas?

John = The first thing I would do is to connect two back to back 3A diodes across each meter movement to protect them from possible damage. The second thing would be to check the calibration of all metered functions against a calibrated DMM, and do whatever it takes to make them read accurately. Third, I would add a suitable glitch-R in the HV+ lead.

Thanks
-John

R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org

OK, I need professional help.

I got a basket-case Henry 3K Ultra some time ago and have been repairing in
my spare time. Amongst the defects it had, was a plate choke flash-over. This
took out the .5 ohm (20 watt?) resistor and diode (on the power supply) that
hold the B- to near ground potential. It also took out a small (.1?) cap at the
plate current meter (in the desk console). The schematic is not correct for
this unit and Henry was no help. I did what I think is correct.

Now my problem:

The grid meter show excessive current. I am convinced this is not "grid
current", but plate current. See the table below for results:

Grid Current Plate Current Power Out

Amp on, not keyed: 75ma 0ma 0W
Amp keyed, no drive 225ma 150ma 0W
Amp keyed, 50W drive >1,000ma 875ma 1,500W

Notice grid current w/ no excitation and how the grid current follows the
plate current. Hmmm...

If I draw out how the metering is wired it looks right. For the grid meter,
here is a .5 ohm resistor shunt from ground to cathode with a 470 ohm, 3 Watt
series dropping resistor from the cathode side of the shunt to the grid meter.
(The other side of the meter is grounded).

For the plate meter, there are two series .1 ohm shunt resistors from the
glitch R to the cathode. The meter is connected across this with a 150 ohm series
dropping resistor between it and the shunt R / glitch R connection.

Any ideas?

Thanks
-John

Sorry, make incorrect, WxHxD not include shaft's length.

I have 20 NOS Variable capacitors, one is 1400PF/1kV(0.65mm spacing ), another one is 200PF/3kV(2mm spacing ).
a set of capacitors(1400P/1kV+200P/3.5kV)=$80, include shipping.WxHxD=92mmx87mmx85mm( include shaft's length),weight=550g , a pair NOS EIMAC 4CX250B in papaer box=$150 I pay the shipping cost.
73! Hsu