Date   

Re: ADF4351 Reference signal

Andy G4JNT
 

The chip squares it up internally 
Enough said...?
'JNT


On Friday, 25 November 2016, g8zha@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

I have a SV1AFN ADF4351 module. I am wondering what is the best reference signal to provide to the PCB.

I am not sure whether to provide a CMOS square wave signal, direct from a 10MHz oscillator, or a sine wave signal from the said oscillator via a low pass filter?

Regards, Rich



ADF4351 Reference signal

g8zha@...
 

I have a SV1AFN ADF4351 module. I am wondering what is the best reference signal to provide to the PCB.

I am not sure whether to provide a CMOS square wave signal, direct from a 10MHz oscillator, or a sine wave signal from the said oscillator via a low pass filter?

Regards, Rich



Re: [not] Radar QRM [at all] - ALL SOLVED!

 

Shame, it looks as if there would be room on the PCB rx. side to include a copy of the LPF at the minimal cost of 4 SM caps!


Re: [not] Radar QRM [at all] - ALL SOLVED!

Andy G4JNT
 

... and now the final bit is solved too - why the interference wasn't noticed before I swapped over the link for separate Rx and Tx ports

When in common port mode of the SG-Labs transverter (default, as supplied) the Rx path from teh common port SMA passes though the low pass filter before hitting the RF switch.   When the link is reconfigured to  the separate Rx input SMA , this filter is no longer in teh receive path.    

Hence the 3G interference breakthrough WAS a result of the reconfiguration

A phot o fteh innards can be seen here, showing the RF path

'JNT


On 25 November 2016 at 11:31, pa0jme@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

That's why I put the lowpass filter on my aerial socket rather than my PA-line. I had to put a bandfilter on 13cm/s to keep the telephone signals out (distance about 250mtrs) as well.
73es Rien PA0JME



Re: [not] Radar QRM [at all] - ALL SOLVED!

pa0jme@...
 

That's why I put the lowpass filter on my aerial socket rather than my PA-line. I had to put a bandfilter on 13cm/s to keep the telephone signals out (distance about 250mtrs) as well.
73es Rien PA0JME


Re: [not] Radar QRM [at all] - ALL SOLVED!

GORDONJ REASON <gordonj.reason@...>
 

Well done , you now have the honour of Proper Hamettry .

On 24 November 2016 at 19:37 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

All solved.  Nothing to do with radars, just a strong 3G base station.   Unjustly blamed Q-Q (altbough they deserve to be blamed anyway)

After making a trip to Portsdown hill with laptop and dongle,  and hearing absolutely nothing at all like the QRM I was getting at home, thoughts turned to other ideas.

Looked up the frequencies of 3G and realised the downlink is in the band 2110 to 2170MHz. A quick calculation and this looked a possibility (with the LO in the transverter being 1152MHz)

2 x 1152 - 144.7 = 2159.3MHz    (144.7MHz being the edge of the audible interference.)   which sits right in the 3G band

So connected the QLoop via a 25dB gain stage to the spectrum analyser, and injected an off-air  marker at 2159.3MHz.   The result can be seen at 
The marker can be seen just left of centre.   So it looked to be a very likely contender  and the frequency is spot-on.

As a final check, I connected the antenna to a 0.3 - 4GHz Double Balanced Mixer, injected 2304MHz from a synth to its LO port and listened to the IF at 144MHz,   

Sound and band characteristics were absolutely  identical to those observed on the transverter,  and MUCH stronger.    So it is clear that is what I am hearing.
The signal is so strong into the SG-Labs transverter, it's forcing its way across the bandpass filter.

A low pass filter common to Rx and Tx will solve the problem, instead of just inserting one in the Tx path to control harmonics.

Andy G4JNT

 


 


 


Re: [not] Radar QRM [at all] - ALL SOLVED!

Andy G4JNT
 

All solved.  Nothing to do with radars, just a strong 3G base station.   Unjustly blamed Q-Q (altbough they deserve to be blamed anyway)

After making a trip to Portsdown hill with laptop and dongle,  and hearing absolutely nothing at all like the QRM I was getting at home, thoughts turned to other ideas.

Looked up the frequencies of 3G and realised the downlink is in the band 2110 to 2170MHz. A quick calculation and this looked a possibility (with the LO in the transverter being 1152MHz)

2 x 1152 - 144.7 = 2159.3MHz    (144.7MHz being the edge of the audible interference.)   which sits right in the 3G band

So connected the QLoop via a 25dB gain stage to the spectrum analyser, and injected an off-air  marker at 2159.3MHz.   The result can be seen at 
The marker can be seen just left of centre.   So it looked to be a very likely contender  and the frequency is spot-on.

As a final check, I connected the antenna to a 0.3 - 4GHz Double Balanced Mixer, injected 2304MHz from a synth to its LO port and listened to the IF at 144MHz,   

Sound and band characteristics were absolutely  identical to those observed on the transverter,  and MUCH stronger.    So it is clear that is what I am hearing.
The signal is so strong into the SG-Labs transverter, it's forcing its way across the bandpass filter.

A low pass filter common to Rx and Tx will solve the problem, instead of just inserting one in the Tx path to control harmonics.

Andy G4JNT


Re: Radar QRM

Rob, M0DTS
 

There was some different radar appeared up here in IO94 for a period  some years back but has not been on again since.
Video here:
https://www.youtube.com/watch?v=AFKv4TfrxXQ

73
Rob

On 11/24/2016 1:50 PM, GORDONJ REASON gordonj.reason@... [ukmicrowaves] wrote:
 

Phased array systems use a lot of individual rx/tx modules ... it only need one to go hooting  , and create a lot of cross mod products ... 

You may get a medal , if you report the problem , as some sad bearded weirdy geek up there , will be trying to find the fault.......

better to have to much information , than too little ...........

On 24 November 2016 at 09:29 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" wrote:

 

 

After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-en ough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is G B3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@yahoog roups.com> wrote:
 

 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day an d discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothi ng to do with the signal rerouting.

Andy  G4JNT

 


 


 

 

 

 

 


 


 



Re: Radar QRM

GORDONJ REASON <gordonj.reason@...>
 

Phased array systems use a lot of individual rx/tx modules ... it only need one to go hooting  , and create a lot of cross mod products ... 

You may get a medal , if you report the problem , as some sad bearded weirdy geek up there , will be trying to find the fault.......

better to have to much information , than too little ...........

On 24 November 2016 at 09:29 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-enough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is GB3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 

 

 

 

 


 


 


Re: Radar QRM

GORDONJ REASON <gordonj.reason@...>
 

Phased array systems use a lot if individualrx/tx modules ... it only need one to go bad , and create a lot of cross mod products ... 

You may get a medal , if you report the problem , as some sad geek up there , will be trying to find the fault.......

better to have to much information , than too little ...........

On 24 November 2016 at 09:29 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-enough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is GB3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 

 

 

 

 


 


 


Re: Radar QRM

GORDONJ REASON <gordonj.reason@...>
 

send them an email ................. 

On 24 November 2016 at 09:29 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-enough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is GB3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 

 

 

 

 


 


 


Re: Radar QRM

John Quarmby
 

Hi Andy

Looking at the broadband plot I wonder if it is some form of phased array radar with a pseudorandom scanning pattern? Hopefully it is just a temporary test system.

73

John G3XDY


On 24/11/2016 09:29, Andy Talbot andy.g4jnt@... [ukmicrowaves] wrote:
After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-enough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is GB3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 






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Re: Radar QRM

Andy G4JNT
 

After a bit of detective work this morning, it appears to beam up on  heading of around 120 deg from me, which just happens to be Portsdown Hill.   But as the interference is very peaky and variable, it is a bit difficult to get a decent resolution on bearing - especially as my QLoop has multiple sidelobes.

Portsdown Hill is near-enough line of sight from here and it the home of what most of my ex-employer became after the semi-privatisation in 2000 - The Land Based Test Site run by QinetiQ  where they have complete mocks-up of ships and naval systems.   It has always been an electrically  noisy environment which is why my old lot moved a few km along the hill back in the 1970's to get a quieter environment, shielded from the Main site.

This signal though is new.

http://www.g4jnt.com/DropF/1296_interference_01.png   Shows the interference at 1297.1MHz in close up

http://www.g4jnt.com/DropF/1296_interference_wideband.png   shows the quite rapid rise in level as we approach 1296.8MHz  (The strong signal under the grey demod marker is GB3IOW off the side of the QLoop)   So the Dx portion of the band is not a problem; it's just in the beacon band and upwards.

http://www.g4jnt.com/DropF/1296_interference_continuum.png   is a broadband plot of the level over a period of just over a minute, showing the varying nature of the broadband signal

Of course, Portsmouth Harbour is only a few degrees round from that heading, so I suppose it could be coming from there - but more likely to be "that Q-Q lot"

Andy  G4JNT



On 23 November 2016 at 23:06, GORDONJ REASON gordonj.reason@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 



Re: Radar QRM

GORDONJ REASON <gordonj.reason@...>
 

any russian , or foreign ships in the area .........?

On 23 November 2016 at 19:38 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT

 


 


 


Radar QRM

Andy G4JNT
 

Somewhat coincidentally after the recent thread here, I think a new radar has either started up around this area, or something has changed in  propagation .

Turned the 1296MHz transverter on the other day and discovered a loud buzz with sweep sounds as I tuned up and down the beacon part of the band.  Haven't yet done a signal capture but it sounds similar to what was being discussed here a few days ago.

Interestingly, the interference disappears completely  when I tune down to 1296.4MHz and lower but is strong up at 1296.7MHz and higher.    It obliterates the MHZ beacon and makes USK all but inaudible.  (GB3IOW is, of course, still Mega)

Anyone else in the South noticed anything ?    I haven't tried any scientific analysis yet, other jobs got in the way, but a DF / beam heading and proper signal capture are needed.

Hearing this noise coincided with transferring the link inside my SG-labs transverter from a common T/R port to separate Tx and Rx, in preparation for installing in a packaged system with a PA.  But I'm 99% certain that is just coincidence and nothing to do with the signal rerouting.

Andy  G4JNT


Re: Tripod turntable

John McCarthy
 

My thoughts would be to cut two circles from good quality ply and recess the lazy Susan into the ply so that the ply has a minimal gap (just enough to turn freely) then something as simple as a clip, clipped to the two pieces of ply to hold the direction.


On Sun, 20 Nov, 2016 at 19:59, Peter Walsh peterdwberkshire@... [ukmicrowaves]
wrote:
 


I have a Leica surveyors tripod for my 3cm /P kit and had a camera pan/tilt head fail in the summer.  I'm intrigued by the simplicity and cost of these units and possibilities.  Also keen to understand their robustness in the field. 

For sure they look like they will rotate smoothly! Any ideas on how to best brake them to hold the dish in a particular direction, welcomed.

Regards...Pete 
G1DFL


On Sunday, November 20, 2016 7:27 PM, "Paul Nickalls paulnick@... [ukmicrowaves]" wrote:


 
No Joy with B&Q online but this guy does a number of sizes. I have bought a 4 inch to evaluate.

eBay item number:
131946474499

Paul
G8AQA

On 20/11/2016 15:50, Geoff Blake melecerties@... [ukmicrowaves] wrote:
 
Maybe I was a bit premature, I searched the local B&Q and not a sign of such. Could fellow ops, when they visit their local B&Q have a looksee if they have any in stock, and email me. I then can contact the store....

Thanks Geoff

#################################################
Geoff Blake,   G8GNZ    JO01fq:   Chelmsford,  Essex,  UK
<geoff@...>    or   <melecerties@...>
Using Linux: Ubuntu 14.04 on Intel or Debian on UltraSparc
    and  Apple  OS  X  El Capitan  on  my  Macbook  Pro.    
                Avoiding Micro$oft like the plague.
#################################################

On 16 November 2016 at 17:46, Geoff Blake <melecerties@...> wrote:
Thanks Mike, I can see it now - a microwavers queue outside B&Q.

Geoff

############################## ###################
Geoff Blake,   G8GNZ    JO01fq:   Chelmsford,  Essex,  UK
<geoff@...>    or   <melecerties@...>
Using Linux: Ubuntu 14.04 on Intel or Debian on UltraSparc
    and  Apple  OS  X  El Capitan  on  my  Macbook  Pro.    
                Avoiding Micro$oft like the plague.
############################## ###################

On 16 November 2016 at 14:09, mb.golfmad@... [ukmicrowaves] <ukmicrowaves@...> wrote:
[Attachment(s) from mb.golfmad@... [ukmicrowaves] included below]

Hi Geoff,

Your wish is my command!!

cheers

Mike G6TRM







Re: Looking for an oscillator fet for DRO Transmitters

g4uvz@...
 

Thanks Chris ...you are a gent!

A


Re: Looking for an oscillator fet for DRO Transmitters

Chris Bartram <g4uvz@...>
 

Hello Adrian

I've got a few FHX35s which might do the trick. I'll put a couple in the post tomorrow.

Don't say that I don't support broadband!!

73

Chris


Looking for an oscillator fet for DRO Transmitters

g4uvz@...
 

I operate a short range 10G link with a friend using a reversed lnb and Puck as the transmitter and Octagon as receive..has worked well for some time ..but the DRO fet has failed and I have run out of 'Blue Spot' LNBs to harvest a replacement!  I have a few of the J Birkett red and blackspots ...but these don't oscillate...which is not a lot of good!


Does anyone know what these transistors are and where I could get half a dozen replacements?


Adrian 


Re: Looking for a capacitor with an APC7 connector on it.

Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby@...>
 

On 21 November 2016 at 15:53, Paul Nickalls paulnick@... [ukmicrowaves] <ukmicrowaves@...> wrote:


Hi David,

I was just about to ask if I had understood that you were just making an offset open circuit. 
 
No. What I described was an offset open, but I soon realized it would not work.

A 6.5mm disc on the end of the line, with an end cap as the other plate, may need too small a gap to be stable.  I don't know how good the location of the centre is on an APC7.  I expect you are looking for a very highly stable capacitance.  Assuming that you could position the centre well you may be looking at different materials for inner and outer for some sort of temperature compensation.

The problem with all this proprietary stuff is you never really know what's going on. But I don't think the value of the capacitance is critical. I believe the only criteria is that is is of a very high Q.

I do have a bit of a problem with getting my head around how these impedance analyzers and LCR meters actually compute results. VNAs I can understand, but the lower frequency things, I'm more puzzled about.



Paul G8AQA

Dave

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