On Wed, 16 Feb 2005 08:08:36 -0500, Dave Hall wrote:

On Tue, 15 Feb 2005 13:36:32 -0600, "Chad Wahls"
wrote:


Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do not
have a schematic here to look around. Did anyone do any "coil spreading"?


I checked the factory service manual last night. They recommend
setting both the driver and final bias to 50 mA. That seems a bit
high, as the driver stages in many other radios are set around 40 mA.

My 2510 is set to factory specs and I've never added any "mods" to it,
and it doesn't oscillate.

Dave
"Sandbagger"


I need a DMM that measures current. any recommendations on one that is good,
without breaking the bank? The Flukes run abour $150 on ebay. I didn't want to
spend that much.

Vinnie S.

On Wed, 16 Feb 2005 08:08:36 -0500, Dave Hall wrote:

On Tue, 15 Feb 2005 13:36:32 -0600, "Chad Wahls"
wrote:


Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do not
have a schematic here to look around. Did anyone do any "coil spreading"?


I checked the factory service manual last night. They recommend
setting both the driver and final bias to 50 mA. That seems a bit
high, as the driver stages in many other radios are set around 40 mA.

My 2510 is set to factory specs and I've never added any "mods" to it,
and it doesn't oscillate.


Dave,

I do not have a RF VTVM or AF VTVM for the slignment. I do have a Tek 2235 scope
and freq counter. I am ordering a DMM. My friend told me instead of the VTVM,
use a DMM with a scope probe. That should work for critical voltages. If not
critical, I can use a scope. Does that sound right?

Vinnie S.

"Lancer" wrote in message
...
On 15 Feb 2005 11:42:41 -0800, "No I Am Not Him"
wrote:

Chad Wahls wrote:
"Dave Hall" wrote in message
...
On Tue, 15 Feb 2005 09:57:06 -0500, Vinnie S.
wrote:

While I solved one problem on SSB, another continues.


I am still having that "carrier" problem on SSB. For some reason,
as soon
as
I speak into the mic, the radio holds power, as if it were on AM.
The TX
meter
on the radio shows this, and the SWR/power meter shows this. The
power is
not
fluctuating with modulation. The ALC was not cranked up. The power
is not
high,
about 20 watts peak. Like I said, it seems to do this as soon
as I speak into the mic. Even a subtle noise will send it to max,
and stay
there. Changed mics, and have the same problem.

So then I tried this.

I took this radio and put it in my car (it's my only radio). When I

connect it
directly to the Wilson 1000 barefoot, I get the same problem on
SSB.
However,
when I go thru the amp, it works perfectly, no power unless I
modulate.
This is
also true if the amp is turned on or off. It appears to be an
impedance
mismatch. Since the amp input is a perfect match, the problem goes
away,
whether
or not the amp power is on or off. Here is the kicker. The SWR on
my home
antenna is about 1.3-1.5 across the band.

The final oscillation is most definitely related to output load
impedance. When I first stumbled onto this problem (In some older
dual
final Galaxy radios), the problem would never show up on the bench
when I used my dummy load. It also didn't show on my base antenna.
But
the problem would happen on the customer's antenna. I managed to
force
the problem on my antenna by using a tuner and de-tuning the match
until the oscillation occurred.

The cover of the radio acts like a capacitor, and it's very
sensitive
to it.

Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until
you
kill the oscillation. But try setting the bias first. If I
remember
right, the bias for the final should be set at somewhere in the 30
-
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure
that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times?
When
changing finals did they change drive components? Unfortunately I do
not
have a schematic here to look around. Did anyone do any "coil
spreading"?

Chad

LOL "coil spreading". See this is exatcly what I was talking about.
Someone is ALWAYS inside a keyclown radio to try and get it to do more
power, more channels. The result is all kinds of problems. You would
never have these problems if you ran legal gear.

Thats why they moved the capacitors to the bottom of the radio, more
room to spread the coils.

Good one! First laugh I've had here in a while!

Chad

On Wed, 16 Feb 2005 08:23:34 -0500, Vinnie S.
wrote:

On Wed, 16 Feb 2005 08:08:36 -0500, Dave Hall wrote:

On Tue, 15 Feb 2005 13:36:32 -0600, "Chad Wahls"
wrote:


Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do not
have a schematic here to look around. Did anyone do any "coil spreading"?


I checked the factory service manual last night. They recommend
setting both the driver and final bias to 50 mA. That seems a bit
high, as the driver stages in many other radios are set around 40 mA.

My 2510 is set to factory specs and I've never added any "mods" to it,
and it doesn't oscillate.

Dave
"Sandbagger"


I need a DMM that measures current. any recommendations on one that is good,
without breaking the bank? The Flukes run abour $150 on ebay. I didn't want to
spend that much.


For current settings, I use a simple 15 year old Radio Shack VOM. It's
analog, but it's not that critical, and they (At least they used to
be) cheap, and available.

I also have a Textronix DMM that does current, but it's not as
portable.

Dave
"Sandbagger"

On Wed, 16 Feb 2005 08:33:04 -0500, Vinnie S.
wrote:

On Wed, 16 Feb 2005 08:08:36 -0500, Dave Hall wrote:

On Tue, 15 Feb 2005 13:36:32 -0600, "Chad Wahls"
wrote:


Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do not
have a schematic here to look around. Did anyone do any "coil spreading"?


I checked the factory service manual last night. They recommend
setting both the driver and final bias to 50 mA. That seems a bit
high, as the driver stages in many other radios are set around 40 mA.

My 2510 is set to factory specs and I've never added any "mods" to it,
and it doesn't oscillate.


Dave,

I do not have a RF VTVM or AF VTVM for the slignment. I do have a Tek 2235 scope
and freq counter. I am ordering a DMM. My friend told me instead of the VTVM,
use a DMM with a scope probe. That should work for critical voltages. If not
critical, I can use a scope. Does that sound right?


A DMM is not necessarily more accurate than a scope, it's just more
precise. If you need to make a voltage reading that goes out 2 decimal
places, the DMM can indicate that (even if it might be beyond its
calibrated accuracy in some cases).

A scope is nice. The TEK 2235 works well. I have one of those and it's
great for doing two tone and modulation tests. You can actually "peak"
a radio with the scope by simply tuning for tallest amplitude of the
waveform. Remember when looking at a scope that it measures in
voltage. Twice the voltage equates to about 4 times the power in
watts. So when you set for 100% modulation, I usually set the carrier
wave for two divisions in amplitude, and then 100% modulation will
increase that to 4 divisions.

A scope is also high impedance so it should not affect circuits all
that much. A scope is basically a voltmeter that displays in the time
domain, so anything you can measure with a DMM can be measured with a
scope.

I also prefer having a spectrum analyzer (I have an HP 8558). It is
real nice for checking spurious emissions and oscillations. Many times
aligning a radio by meter alone will not give the cleanest output. I
usually align with the analyzer for cleanest output.

Dave
"Sandbagger"

I picked up an 8558 a couple of years ago..........nice unit. I did hear
mention of an RF voltmeter...........this is handy if you are aligning the
PLL or the low level exciter stages, but a 'scope does fine.

Pete

"Dave Hall" wrote in message
...
On Wed, 16 Feb 2005 08:33:04 -0500, Vinnie S.
wrote:

On Wed, 16 Feb 2005 08:08:36 -0500, Dave Hall
wrote:

On Tue, 15 Feb 2005 13:36:32 -0600, "Chad Wahls"
wrote:


Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure
that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do
not
have a schematic here to look around. Did anyone do any "coil
spreading"?


I checked the factory service manual last night. They recommend
setting both the driver and final bias to 50 mA. That seems a bit
high, as the driver stages in many other radios are set around 40 mA.

My 2510 is set to factory specs and I've never added any "mods" to it,
and it doesn't oscillate.


Dave,

I do not have a RF VTVM or AF VTVM for the slignment. I do have a Tek 2235
scope
and freq counter. I am ordering a DMM. My friend told me instead of the
VTVM,
use a DMM with a scope probe. That should work for critical voltages. If
not
critical, I can use a scope. Does that sound right?


A DMM is not necessarily more accurate than a scope, it's just more
precise. If you need to make a voltage reading that goes out 2 decimal
places, the DMM can indicate that (even if it might be beyond its
calibrated accuracy in some cases).

A scope is nice. The TEK 2235 works well. I have one of those and it's
great for doing two tone and modulation tests. You can actually "peak"
a radio with the scope by simply tuning for tallest amplitude of the
waveform. Remember when looking at a scope that it measures in
voltage. Twice the voltage equates to about 4 times the power in
watts. So when you set for 100% modulation, I usually set the carrier
wave for two divisions in amplitude, and then 100% modulation will
increase that to 4 divisions.

A scope is also high impedance so it should not affect circuits all
that much. A scope is basically a voltmeter that displays in the time
domain, so anything you can measure with a DMM can be measured with a
scope.

I also prefer having a spectrum analyzer (I have an HP 8558). It is
real nice for checking spurious emissions and oscillations. Many times
aligning a radio by meter alone will not give the cleanest output. I
usually align with the analyzer for cleanest output.

Dave
"Sandbagger"

On Thu, 17 Feb 2005 11:37:30 -0500, Me wrote:

I took this radio and put it in my car (it's my only radio). When I connect it
directly to the Wilson 1000 barefoot, I get the same problem on SSB. However,
when I go thru the amp, it works perfectly, no power unless I modulate. This is
also true if the amp is turned on or off. It appears to be an impedance
mismatch. Since the amp input is a perfect match, the problem goes away, whether
or not the amp power is on or off. Here is the kicker. The SWR on my home
antenna is about 1.3-1.5 across the band.

Any suggestions?



Vinnie S.


Hi Vinne,
Over the years, I have seen this problem a number of
times, and I found one of the wire wound coils in the back of the
radio was overcoupled, and causing the nasty parasitic you speak of.
You key the mike on SSB, and, after you unkey, there is a full scale
carrier being transmitted...

Exactly.

Resetting the bias didn't help, however,
streching the coil, reducing the inductance always worked.
Unfortunately, Its been a few years since I have worked on a HR-2510,
but can tell you it is the coil is all the way in the back, near the
middle, right by the heat sink, and as I remember, parallel to the
rear panel, and has a ceramic cap in front of it, making it a little
hard to strech the coil. After you take the top off, key the mike on
ssb, and when the parasitic shows up, strech the coil until the RF
power meter drops back down to zero. After you do this, the parasitic
will go away forever. I have fixed at least 10 HR-2510s in this
manner, and never had a problem again. One more point worth mentioning
though. As I recall, I had at least one or two that the parasitic
"went away" when you took off the covers.. You still strech the coil,
and this will fix it, however, a little harder to identify the coil...
I'm sorry I can't recall off the top of my head which coil it is
exactly, but its not hard to find.. If I had a 2510 in front of me, I
could look and tell you, but I don't... As there are just a few coils
that you can strech, you can do it trial by error, and if you choose
the wrong coil, just push the windings back. Anyway, best luck! es 73
Tony..


I will take a look. Togerbird also emailed me, and said to put a mica insulator
between the final and chassis. Since the transistor was not using the chassis as
common, having it ground to the chassis causes this problem.

Here is his comment:

"You need to add an insulator between the final and the Heatsink.
Simply unscrew the final mounting screw, and you should be able to slide a mica
insulator between the final and heatsink.


Make sure to use heatsink compound on both sides of the insulator.


Now for the reason: Uniden chose not to use an insulator. The mounting tab of
the final is Power ground. (emitter)
The heatsink is Chassi Ground. Connecting the final emitter to chassi ground (at
the mounting Screw) can sometimes cause an RF Ground loop."

Anyway, I will take a look at your solution too. Thanks.


Vinnie S.

On Thu, 17 Feb 2005 18:07:13 -0500, Vinnie S. wrote:

On Thu, 17 Feb 2005 11:37:30 -0500, Me wrote:

I took this radio and put it in my car (it's my only radio). When I connect it
directly to the Wilson 1000 barefoot, I get the same problem on SSB. However,
when I go thru the amp, it works perfectly, no power unless I modulate. This is
also true if the amp is turned on or off. It appears to be an impedance
mismatch. Since the amp input is a perfect match, the problem goes away, whether
or not the amp power is on or off. Here is the kicker. The SWR on my home
antenna is about 1.3-1.5 across the band.

Any suggestions?



Vinnie S.


Hi Vinne,
Over the years, I have seen this problem a number of
times, and I found one of the wire wound coils in the back of the
radio was overcoupled, and causing the nasty parasitic you speak of.
You key the mike on SSB, and, after you unkey, there is a full scale
carrier being transmitted...

Exactly.

Resetting the bias didn't help, however,
streching the coil, reducing the inductance always worked.
Unfortunately, Its been a few years since I have worked on a HR-2510,
but can tell you it is the coil is all the way in the back, near the
middle, right by the heat sink, and as I remember, parallel to the
rear panel, and has a ceramic cap in front of it, making it a little
hard to strech the coil. After you take the top off, key the mike on
ssb, and when the parasitic shows up, strech the coil until the RF
power meter drops back down to zero. After you do this, the parasitic
will go away forever. I have fixed at least 10 HR-2510s in this
manner, and never had a problem again. One more point worth mentioning
though. As I recall, I had at least one or two that the parasitic
"went away" when you took off the covers.. You still strech the coil,
and this will fix it, however, a little harder to identify the coil...
I'm sorry I can't recall off the top of my head which coil it is
exactly, but its not hard to find.. If I had a 2510 in front of me, I
could look and tell you, but I don't... As there are just a few coils
that you can strech, you can do it trial by error, and if you choose
the wrong coil, just push the windings back. Anyway, best luck! es 73
Tony..


I will take a look. Togerbird also emailed me, and said to put a mica insulator
between the final and chassis. Since the transistor was not using the chassis as
common, having it ground to the chassis causes this problem.

Here is his comment:

"You need to add an insulator between the final and the Heatsink.
Simply unscrew the final mounting screw, and you should be able to slide a mica
insulator between the final and heatsink.


Make sure to use heatsink compound on both sides of the insulator.


Now for the reason: Uniden chose not to use an insulator. The mounting tab of
the final is Power ground. (emitter)
The heatsink is Chassi Ground. Connecting the final emitter to chassi ground (at
the mounting Screw) can sometimes cause an RF Ground loop."

Anyway, I will take a look at your solution too. Thanks.



Holy crap, that might have done it. While I did not spreak the coil, it appeared
to be pushed or slanted to one side. I just straightened it out a bit. Seems to
work. Will still do alignment. I will get back to you !


Vinnie S.

On Fri, 18 Feb 2005 05:26:14 -0500, Vinnie S.
wrote in :

snip
Holy crap, that might have done it. While I did not spreak the coil, it appeared
to be pushed or slanted to one side. I just straightened it out a bit. Seems to
work. Will still do alignment. I will get back to you !


That should stroke Dave's ego a little bit -- he needs it right about
now.





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Frank Gilliland wrote:
On Fri, 18 Feb 2005 05:26:14 -0500, Vinnie S.
wrote in :

snip
Holy crap, that might have done it. While I did not spreak the coil, it
appeared to be pushed or slanted to one side. I just straightened it out
a bit. Seems to work. Will still do alignment. I will get back to you !

That should stroke Dave's ego a little bit -- he needs it right about
now.

Ya do what ya can.

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