[IC-7000] Oscillation


Don Clark
 

You might want to look at your power supply. Especially if it is a switching type.

On 12/28/2015 3:33 PM, James Brock jamesbrock@... [ic7000] wrote:
 
 This is somewhat hard to explain.  But rather frequently now I get an oscillation showing up on my JT65 screen.  You can see it slowly sweep across the screen from right to left.  Strange thing I hold my hand over the case blower it stops and goes the other direction. No doubt somewhat heat related. 

If I have the input on the antenna that has not yet been tuned (remotely) to frequency the oscillation is worse.  Put on the carrier to get the antenna tuner on frequently and the oscillation considerably lower in intensity, sometimes goes off.

When it gets so bad nothing works I recycle it by turning input DC power on and off. 

It is considerably worse when I have the preamplifier off. 

Recapping, to get it to quit or so low I can operate I make sure the antenna is tuned to frequency. I turn on the preamplifier. And when that doesn't work, turn the power switch off and on. 

It has been going like this for several months. I talked to ICOM about it and they said to reset it. That didn't do any good at all.  The tech at ICOM acted as if something like this could not happen.

Anyone out there have a parasitic oscillation running around? 

I am rather inclined to think it is in the RF amplifier stage.

HELP 

W7DAU
James Brock 541-868-5827


Howard Jones
 

Good advice from Don, try an alternative power supply, I have had this experience with switch mode supplies

reghrtads

Howard VK3QA

On Tue, Dec 29, 2015 at 10:47 AM, Don kb5kwv@... [ic7000] <ic7000@...> wrote:
 

You might want to look at your power supply. Especially if it is a switching type.

On 12/28/2015 3:33 PM, James Brock jamesbrock@... [ic7000] wrote:
 
 This is somewhat hard to explain.  But rather frequently now I get an oscillation showing up on my JT65 screen.  You can see it slowly sweep across the screen from right to left.  Strange thing I hold my hand over the case blower it stops and goes the other direction. No doubt somewhat heat related. 

If I have the input on the antenna that has not yet been tuned (remotely) to frequency the oscillation is worse.  Put on the carrier to get the antenna tuner on frequently and the oscillation considerably lower in intensity, sometimes goes off.

When it gets so bad nothing works I recycle it by turning input DC power on and off. 

It is considerably worse when I have the preamplifier off. 

Recapping, to get it to quit or so low I can operate I make sure the antenna is tuned to frequency. I turn on the preamplifier. And when that doesn't work, turn the power switch off and on. 

It has been going like this for several months. I talked to ICOM about it and they said to reset it. That didn't do any good at all.  The tech at ICOM acted as if something like this could not happen.

Anyone out there have a parasitic oscillation running around? 

I am rather inclined to think it is in the RF amplifier stage.

HELP 

W7DAU
James Brock 541-868-5827




--
Regards

Howard Jones



Richard
 

There are people not using linear power supplies???

C. Richard Pumphrey
WN9DDV


On Dec 29, 2015, at 4:46 AM, Howard Jones howardjones155@... [ic7000] <ic7000@...> wrote:

 

Good advice from Don, try an alternative power supply, I have had this experience with switch mode supplies

reghrtads

Howard VK3QA

On Tue, Dec 29, 2015 at 10:47 AM, Don kb5kwv@... [ic7000] <ic7000@...> wrote:
 

You might want to look at your power supply. Especially if it is a switching type.

On 12/28/2015 3:33 PM, James Brock jamesbrock@... [ic7000] wrote:
 
 This is somewhat hard to explain.  But rather frequently now I get an oscillation showing up on my JT65 screen.  You can see it slowly sweep across the screen from right to left.  Strange thing I hold my hand over the case blower it stops and goes the other direction. No doubt somewhat heat related. 

If I have the input on the antenna that has not yet been tuned (remotely) to frequency the oscillation is worse.  Put on the carrier to get the antenna tuner on frequently and the oscillation considerably lower in intensity, sometimes goes off.

When it gets so bad nothing works I recycle it by turning input DC power on and off. 

It is considerably worse when I have the preamplifier off. 

Recapping, to get it to quit or so low I can operate I make sure the antenna is tuned to frequency. I turn on the preamplifier. And when that doesn't work, turn the power switch off and on. 

It has been going like this for several months. I talked to ICOM about it and they said to reset it. That didn't do any good at all.  The tech at ICOM acted as if something like this could not happen.

Anyone out there have a parasitic oscillation running around? 

I am rather inclined to think it is in the RF amplifier stage.

HELP 

W7DAU
James Brock 541-868-5827




--
Regards

Howard Jones



Alan Johnson <little_pig_let_me_in@...>
 

Hate to have to bring you into the 21st century, but there have been quiet smps's for some time now. 

I use a variety of smps and linear, and even with my EME system, there's no discernible difference with a quality smps. 

As with anything, buy cheap crap and you get crap performance. 

Alan VK3DXE


On 30 Dec 2015, at 07:02, Richard wn9ddv@... [ic7000] <ic7000@...> wrote:

 

There are people not using linear power supplies???

C. Richard Pumphrey
WN9DDV


On Dec 29, 2015, at 4:46 AM, Howard Jones howardjones155@... [ic7000] <ic7000@...> wrote:

 

Good advice from Don, try an alternative power supply, I have had this experience with switch mode supplies

reghrtads

Howard VK3QA

On Tue, Dec 29, 2015 at 10:47 AM, Don kb5kwv@... [ic7000] <ic7000@...> wrote:
 

You might want to look at your power supply. Especially if it is a switching type.

On 12/28/2015 3:33 PM, James Brock jamesbrock@... [ic7000] wrote:
 
 This is somewhat hard to explain.  But rather frequently now I get an oscillation showing up on my JT65 screen.  You can see it slowly sweep across the screen from right to left.  Strange thing I hold my hand over the case blower it stops and goes the other direction. No doubt somewhat heat related. 

If I have the input on the antenna that has not yet been tuned (remotely) to frequency the oscillation is worse.  Put on the carrier to get the antenna tuner on frequently and the oscillation considerably lower in intensity, sometimes goes off.

When it gets so bad nothing works I recycle it by turning input DC power on and off. 

It is considerably worse when I have the preamplifier off. 

Recapping, to get it to quit or so low I can operate I make sure the antenna is tuned to frequency. I turn on the preamplifier. And when that doesn't work, turn the power switch off and on. 

It has been going like this for several months. I talked to ICOM about it and they said to reset it. That didn't do any good at all.  The tech at ICOM acted as if something like this could not happen.

Anyone out there have a parasitic oscillation running around? 

I am rather inclined to think it is in the RF amplifier stage.

HELP 

W7DAU
James Brock 541-868-5827




--
Regards

Howard Jones



 

On 30/12/2015 1:12 PM, Alan Johnson little_pig_let_me_in@... [ic7000] wrote:
Hate to have to bring you into the 21st century, but there have been quiet smps's for some time now. 

I use a variety of smps and linear, and even with my EME system, there's no discernible difference with a quality smps. 

As with anything, buy cheap crap and you get crap performance.

I've used a shack SMPS since 2004.  Any noise it generates is well below the local noise floor on all bands, and voltage regulation has been spot on.   With the high frequency of hot days (35C+) up here in summer and a significant amount of 24x7 gear, it's not an environment I want to run a linear PSU in, too much hassle cooling the darned thing! 

-- 
73 de Tony VK3JED/VK3IRL
http://vkradio.com


Ed G
 

I have 4 switching supplies for ham use. 3 are server power supplies & present no RFI whatsoever.
1 is 3 in series & 2 series stacks in parallel of adjusted 5VDC LED 100A supplies. It is all neatly packaged in an old PC case with a CLC filter that honestly wasn't needed. I use that to run a 1KX solid state amp & even at full tilt, bypassing the filtering, it is RFI quiet.

Ed