Date   

Re: Microwave Modules MMT50/144 Help!

Bill N6GHz
 

Thanks Alan for your reply. I did see Dave's web site and looked at the 70/144 transverter in the "black box". Unfortunately it's different enough from the "fancy" version that I have. I think I'll have to remove the pcb's and do some circuit tracing. Oh well.
Regards and thanks for your help...Bill - N6GHz

On 6/23/2021 2:57:20 PM, Alan Melia via groups.io <alan.melia@...> wrote:

Hi Bill, MM was a British firm and I believe we only had limited access to 50MHz before the mid to late 1980s. However we did have activity on the 70MHz band. Because of the similarity of the products and the ''reuse'' of designs I am guessing the MMT70/144 may be as close as you can easily get.This is available on Dave Robinson's site (ex WW2R now G4FRE) If you dont have it Dave's dowloadables are at http://www.g4fre.com/MM.htm
 
Best Wishes
Alan
G3NYK
----- Original Message -----
From: Bill N6GHz
Sent: Wednesday, June 23, 2021 9:52 PM
Subject: [UKMicrowaves] Microwave Modules MMT50/144 Help!

Hello All,.
I'm back working on my MMT 50/144. I've searched the Web in vain for a schematic and have not found anything except data on some of the other models. Does anyone have a copy of the schematic that would share??? The model in question is the one shown below.
Regards...Bill - N6GHz

Virus-free. www.avg.com


Re: Microwave Modules MMT50/144 Help!

Barry VE4MA <ve4ma@...>
 

Sorry Bill if I looked closer at the picture I would have realized that your unit has a 144 IF and 50 MHz RF side also.

It would be interesting to compare notes on the RF part of the unit.  I had a power transistor  fail  ( High VSWR) , have a replacement but did not complete the repair

Barry VE4MA


From: "ve4ma" <ve4ma@...>
To: "UKMicrowaves" <UKMicrowaves@groups.io>
Sent: Wednesday, June 23, 2021 5:41:54 PM
Subject: [UKMicrowaves] Microwave Modules MMT50/144 Help!

GA Bill, 

I assume that 50 MHz is the IF for that transverter?  I have a MMT 144 MHz IF & 50 MHz RF transverter in the classic black box  but also do not have a  manual 

Best 73
Barry VE4MA


Microwave Modules MMT50/144 Help!

Barry VE4MA <ve4ma@...>
 

GA Bill, 

I assume that 50 MHz is the IF for that transverter?  I have a MMT 144 MHz IF & 50 MHz RF transverter in the classic black box  but also do not have a  manual 

Best 73
Barry VE4MA


Re: Q0-100 Web-SDR 198Hz frequency error

Dave G8GKQ
 

Thanks Simon

 

When Andy first mentioned the problem, I thought that the GPSDO had lost lock again, like it did a few months back before Phil replaced the aerial cable.  However, it appears to be in lock.  I don’t think that there is anything that needs a hardware fix.  The WebSDR was not built to have absolute frequency accuracy, but I believe that it would have, were it not for the systemic frequency error that Andy has identified.

 

When the WebSDR first went live, there was a lot of investigation into this frequency error.  Andy may be able to get more information about it by asking on the AMSAT-DL QO-100 chat and forums.  I did not see it as important at the time, so do not remember the details.

 

The narrow band beacons are uploaded from Bochum in Germany; the Wideband beacon comes from the SCC in Qatar.

 

All the code for the Wideband and Narrowband SDRs are on the BATC Github site.  https://github.com/BritishAmateurTelevisionClub  Phil does have remote access to the server, but as it has run reliably for 2 years with only security updates, we would be very reluctant to make unnecessary changes.

 

Dave, G8GKQ

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Simon Brown
Sent: 23 June 2021 20:08
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Dave,

 

If it’s something that simple couldn’t a local ham help – I’m thinking about Robin M0RRX who lives close to the site. I see the dishes from my garden – quite close but a heck of a trek to get around the Helford passage.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Dave G8GKQ
Sent: 22 June 2021 16:20
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Hi Andy

 

The GHY WebSDR was never intended to be a frequency reference, just something to enable a wider audience to monitor the transponder.

 

I think that it is GPS locked (stable, but not absolutely correct) at the moment, but we have had some recent issues with the GPS [antenna cable].  Unfortunately, site access is difficult at present, and it always means an expensive overnight stay.

 

Dave, G8GKQ

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 

Andy

 


Re: Microwave Modules MMT50/144 Help!

Alan Melia
 


Hi Bill, MM was a British firm and I believe we only had limited access to 50MHz before the mid to late 1980s. However we did have activity on the 70MHz band. Because of the similarity of the products and the ''reuse'' of designs I am guessing the MMT70/144 may be as close as you can easily get.This is available on Dave Robinson's site (ex WW2R now G4FRE) If you dont have it Dave's dowloadables are at http://www.g4fre.com/MM.htm
 
Best Wishes
Alan
G3NYK

----- Original Message -----
From: Bill N6GHz
Sent: Wednesday, June 23, 2021 9:52 PM
Subject: [UKMicrowaves] Microwave Modules MMT50/144 Help!

Hello All,.
I'm back working on my MMT 50/144. I've searched the Web in vain for a schematic and have not found anything except data on some of the other models. Does anyone have a copy of the schematic that would share??? The model in question is the one shown below.
Regards...Bill - N6GHz

Virus-free. www.avg.com


Microwave Modules MMT50/144 Help!

Bill N6GHz
 

Hello All,.
I'm back working on my MMT 50/144. I've searched the Web in vain for a schematic and have not found anything except data on some of the other models. Does anyone have a copy of the schematic that would share??? The model in question is the one shown below.
Regards...Bill - N6GHz

Virus-free. www.avg.com


Re: Q0-100 Web-SDR 198Hz frequency error

Andy G4JNT
 

A thought just struck:
'Orbitron'  gives the uplink and downlink Doppler shifts.    Total observed on the beacons will be the sum of these.



On Wed, 23 Jun 2021 at 20:13, Andy Talbot <andy.g4jnt@...> wrote:
If it's a constant offset - or at least one that only varies a few Hz - it's not an issue and can just be taken out in calibration.   And I did some testing of it today at different settings.  All show the same error so it's just a case of doing it a few more times to confirm.

Bearing in mind it's directly locked to a GPSDO, there is an inherent short term stability / wobble on it, anyway, of a few Hz RMS with rapid excursions of 10Hz seen.


On Wed, 23 Jun 2021 at 20:07, Simon Brown <simon@...> wrote:

Dave,

 

If it’s something that simple couldn’t a local ham help – I’m thinking about Robin M0RRX who lives close to the site. I see the dishes from my garden – quite close but a heck of a trek to get around the Helford passage.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Dave G8GKQ
Sent: 22 June 2021 16:20
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Hi Andy

 

The GHY WebSDR was never intended to be a frequency reference, just something to enable a wider audience to monitor the transponder.

 

I think that it is GPS locked (stable, but not absolutely correct) at the moment, but we have had some recent issues with the GPS [antenna cable].  Unfortunately, site access is difficult at present, and it always means an expensive overnight stay.

 

Dave, G8GKQ

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 


Re: Q0-100 Web-SDR 198Hz frequency error

Andy G4JNT
 

If it's a constant offset - or at least one that only varies a few Hz - it's not an issue and can just be taken out in calibration.   And I did some testing of it today at different settings.  All show the same error so it's just a case of doing it a few more times to confirm.

Bearing in mind it's directly locked to a GPSDO, there is an inherent short term stability / wobble on it, anyway, of a few Hz RMS with rapid excursions of 10Hz seen.


On Wed, 23 Jun 2021 at 20:07, Simon Brown <simon@...> wrote:

Dave,

 

If it’s something that simple couldn’t a local ham help – I’m thinking about Robin M0RRX who lives close to the site. I see the dishes from my garden – quite close but a heck of a trek to get around the Helford passage.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Dave G8GKQ
Sent: 22 June 2021 16:20
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Hi Andy

 

The GHY WebSDR was never intended to be a frequency reference, just something to enable a wider audience to monitor the transponder.

 

I think that it is GPS locked (stable, but not absolutely correct) at the moment, but we have had some recent issues with the GPS [antenna cable].  Unfortunately, site access is difficult at present, and it always means an expensive overnight stay.

 

Dave, G8GKQ

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 


Re: Q0-100 Web-SDR 198Hz frequency error

Andy G4JNT
 

Yes indeed.  They are uplimnked from DK land, and use. I think, a Rubidium or GPS locked source.   So their frequency accuracy can be relied on for a few Hz.   
The error in the satellite appears to amount to around 100Hz, but without doing a full 24 hour measurement to remove Doppler, (in the absence of exact ephemeris for calculating it) the two can't be separated and the satellite LO element isolated.

The GH WebSDR is definitely 190Hz or so out




On Wed, 23 Jun 2021 at 20:04, Simon Brown <simon@...> wrote:

Andy,

 

I believe the beacons are all sent from either AMSAT-DL or the hams in QATAR, not generated on the satellite so this introduces another possible (but unlikely) source of error.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io <ukmicrowaves@groups.io>
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 


Re: Q0-100 Web-SDR 198Hz frequency error

Simon Brown
 

Dave,

 

If it’s something that simple couldn’t a local ham help – I’m thinking about Robin M0RRX who lives close to the site. I see the dishes from my garden – quite close but a heck of a trek to get around the Helford passage.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Dave G8GKQ
Sent: 22 June 2021 16:20
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Hi Andy

 

The GHY WebSDR was never intended to be a frequency reference, just something to enable a wider audience to monitor the transponder.

 

I think that it is GPS locked (stable, but not absolutely correct) at the moment, but we have had some recent issues with the GPS [antenna cable].  Unfortunately, site access is difficult at present, and it always means an expensive overnight stay.

 

Dave, G8GKQ

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 


Re: Q0-100 Web-SDR 198Hz frequency error

Simon Brown
 

Andy,

 

I believe the beacons are all sent from either AMSAT-DL or the hams in QATAR, not generated on the satellite so this introduces another possible (but unlikely) source of error.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Andy G4JNT
Sent: 22 June 2021 16:09
To: UK Microwaves groups.io <ukmicrowaves@groups.io>
Subject: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

Just checked teh Goonhilly Web-SDR and there is close to 200Hz discrepancy in the tone freq between my fully locked receiving system and it

 

(At 1504z, 22 June 2021) WebSDR tuned to 10489998.00, and the lower keyed tone of the upper beacon comes out at 1681Hz

 

On my system set at the same tuning point, the tone is 1485Hz

 

If I generate a local signal at 10490MHz from a separate synth the resulting tone is 2000.00Hz as expected.

 

Conclusion - Goonhilly Web-SDR  has a frequency locking error

 

 

 


Re: Q0-100 Web-SDR 198Hz frequency error

DD1US
 

Hi Andy,

 

as far as I know the Airspy does have a “ppm” setting to compensate errors in the internal osciallator.

 

I am not sure, but maybe you have to set that value to zero when using an external reference !?

 

Kind regards

 

Matthias

 

www.dd1us.de

 

 

Von: UKMicrowaves@groups.io <UKMicrowaves@groups.io> Im Auftrag von Andy G4JNT
Gesendet: Mittwoch, 23. Juni 2021 16:59
An: UK Microwaves groups.io <UKMicrowaves@groups.io>
Betreff: Re: [UKMicrowaves] Q0-100 Web-SDR 198Hz frequency error

 

The same discrepancy of 190Hz is - to within a couple of Hz - there today as well.

Looking at the block diagram of the WebSDR I see they use an Airspy locked to the same GPSDO, but does anyone know for certain how the Airspy interprets the tuning information it is sent?

 

The FDM-Dup used at my end, when set to USB the 'dial' frequency is that of the suppressed carrier, or a zero frequency tone.

Is this the same setting used on the Airspy?

Could there be an offset introduced somewhere in the setting chain?   The frequency setting of GH appears to be  in 30Hz increments, but rounding to something else.  IN all cases, I used the actual value showing on the display (shown in kHz)

 

Comparing the two beacon signals to my (all locked) uplink, they are within 1Hz of each other when using both my downlink and Goonhilly.   SO the beacon signals can still be used as reliable frequency offset indicators to Hz accuracy.

 

BUT, the keying of the upper and lower beacons  takes a bit of interpreting as to which tone is which.

 

For CW listening purposes both key in the same direction, rest/carrier  and key down are on the lower of the two tone frequencies.    Key up is 400Hz above that.   (The opposite to the standard defined for terrestrial beacon keying, I think)

On the lower beacon at 10489.500 the lowest frequency, is the reference 10489.50000,   and key up is the higher freq, moving into the passband

But

On the higher beacon, the carrier /key down is 400Hz below the edge of the passband and the key up higher tone is the one that defines teh passband edge at 10490.000000MHz

 

 

Andy

 

 

On Wed, 23 Jun 2021 at 13:31, Andy Talbot <andy.g4jnt@...> wrote:

As mentioned yesterday, I measured this Doppler a while back and you can read it at http://g4jnt.com/QO100_Stab.pdf   but that is not the issue here.

 

The discrepancy spotted yesterday is between my FULLY LOCKED system  and the GOONHILLY Web SDR.

I see I hadn't actually measured the Goonhilly accuracy back in those tests of 2019, that was all about satellite and the ground station beacon's stability.

 

Will do some more tests before too long..

 

Andy

 

 

 

On Wed, 23 Jun 2021 at 13:25, Dave_G0WBX via groups.io <g8kbvdave=googlemail.com@groups.io> wrote:

WRT:

From: Gary M1EGI
Date: Tue, 22 Jun 2021 10:33:22 PDT

Hi Andy,

 

Could some of this be explained by the satellite itself?

 

Oscillators used, thermal changes onboard due to activity on the main payload?

 

Just a thought.

 


Plus the bird itself is not in a true fixed point (WRT the ground stations).

 

If it's part of a cluster in particular it will move around, I think in a 24 hour cycle.

 

What does the unexpected offset show 12 hours later, if some 200Hz the other way, maybe that's the cause?

 

This was explained to me some years ago, by one of the site guys we worked with, when involved with a new DBS uplink install that we were providing the TX PA's for.   But I don't remember the sort of figures he illustrated things with, but the frequencies used were in the 12 GHz area.

 

(That, as a result of a question I asked, relating to why the antenna positioners kept whirring every few minutes, if the satellite was in a "geostationary" orbit.   That resulted in a good 45 minutes very interesting diversion from amplifier problems, and a visit to one other much older uplink facility on the same site, to see a chart recorder output.)

 

73.

 

Dave G8KBV

 

 

 

 

 

-- 
Created on and sent from a Unix like PC running and using free and open source software:
 


Re: Q0-100 Web-SDR 198Hz frequency error

Andy G4JNT
 

The same discrepancy of 190Hz is - to within a couple of Hz - there today as well.
Looking at the block diagram of the WebSDR I see they use an Airspy locked to the same GPSDO, but does anyone know for certain how the Airspy interprets the tuning information it is sent?

The FDM-Dup used at my end, when set to USB the 'dial' frequency is that of the suppressed carrier, or a zero frequency tone.
Is this the same setting used on the Airspy?
Could there be an offset introduced somewhere in the setting chain?   The frequency setting of GH appears to be  in 30Hz increments, but rounding to something else.  IN all cases, I used the actual value showing on the display (shown in kHz)

Comparing the two beacon signals to my (all locked) uplink, they are within 1Hz of each other when using both my downlink and Goonhilly.   SO the beacon signals can still be used as reliable frequency offset indicators to Hz accuracy.

BUT, the keying of the upper and lower beacons  takes a bit of interpreting as to which tone is which.

For CW listening purposes both key in the same direction, rest/carrier  and key down are on the lower of the two tone frequencies.    Key up is 400Hz above that.   (The opposite to the standard defined for terrestrial beacon keying, I think)
On the lower beacon at 10489.500 the lowest frequency, is the reference 10489.50000,   and key up is the higher freq, moving into the passband
But
On the higher beacon, the carrier /key down is 400Hz below the edge of the passband and the key up higher tone is the one that defines teh passband edge at 10490.000000MHz


Andy


On Wed, 23 Jun 2021 at 13:31, Andy Talbot <andy.g4jnt@...> wrote:
As mentioned yesterday, I measured this Doppler a while back and you can read it at http://g4jnt.com/QO100_Stab.pdf   but that is not the issue here.

The discrepancy spotted yesterday is between my FULLY LOCKED system  and the GOONHILLY Web SDR.
I see I hadn't actually measured the Goonhilly accuracy back in those tests of 2019, that was all about satellite and the ground station beacon's stability.

Will do some more tests before too long..



On Wed, 23 Jun 2021 at 13:25, Dave_G0WBX via groups.io <g8kbvdave=googlemail.com@groups.io> wrote:

WRT:

From: Gary M1EGI
Date: Tue, 22 Jun 2021 10:33:22 PDT

Hi Andy,

Could some of this be explained by the satellite itself?

Oscillators used, thermal changes onboard due to activity on the main payload?

Just a thought.


Plus the bird itself is not in a true fixed point (WRT the ground stations).

If it's part of a cluster in particular it will move around, I think in a 24 hour cycle.

What does the unexpected offset show 12 hours later, if some 200Hz the other way, maybe that's the cause?

This was explained to me some years ago, by one of the site guys we worked with, when involved with a new DBS uplink install that we were providing the TX PA's for.   But I don't remember the sort of figures he illustrated things with, but the frequencies used were in the 12 GHz area.

(That, as a result of a question I asked, relating to why the antenna positioners kept whirring every few minutes, if the satellite was in a "geostationary" orbit.   That resulted in a good 45 minutes very interesting diversion from amplifier problems, and a visit to one other much older uplink facility on the same site, to see a chart recorder output.)

73.

Dave G8KBV

 



-- 
Created on and sent from a Unix like PC running and using free and open source software:


[camb-hams] 23cm Quad Loop Yagi

John Worsnop
 



---------- Forwarded message ---------
From: g6ohm@... via groups.io <g6ohm=talktalk.net@groups.io>
Date: Wed, 23 Jun 2021 at 10:43
Subject: [camb-hams] 23cm Quad Loop Yagi
To: camb-hams@groups io <camb-hams@groups.io>


To everyone who enquired about the Quad Loop Yagi.

It has now been sold.

Many thanks.

 73 Andy G6OHM. Sent by Amazon Fire Tablet.





Re: Q0-100 Web-SDR 198Hz frequency error

Andy G4JNT
 

As mentioned yesterday, I measured this Doppler a while back and you can read it at http://g4jnt.com/QO100_Stab.pdf   but that is not the issue here.

The discrepancy spotted yesterday is between my FULLY LOCKED system  and the GOONHILLY Web SDR.
I see I hadn't actually measured the Goonhilly accuracy back in those tests of 2019, that was all about satellite and the ground station beacon's stability.

Will do some more tests before too long..



On Wed, 23 Jun 2021 at 13:25, Dave_G0WBX via groups.io <g8kbvdave=googlemail.com@groups.io> wrote:

WRT:

From: Gary M1EGI
Date: Tue, 22 Jun 2021 10:33:22 PDT

Hi Andy,

Could some of this be explained by the satellite itself?

Oscillators used, thermal changes onboard due to activity on the main payload?

Just a thought.


Plus the bird itself is not in a true fixed point (WRT the ground stations).

If it's part of a cluster in particular it will move around, I think in a 24 hour cycle.

What does the unexpected offset show 12 hours later, if some 200Hz the other way, maybe that's the cause?

This was explained to me some years ago, by one of the site guys we worked with, when involved with a new DBS uplink install that we were providing the TX PA's for.   But I don't remember the sort of figures he illustrated things with, but the frequencies used were in the 12 GHz area.

(That, as a result of a question I asked, relating to why the antenna positioners kept whirring every few minutes, if the satellite was in a "geostationary" orbit.   That resulted in a good 45 minutes very interesting diversion from amplifier problems, and a visit to one other much older uplink facility on the same site, to see a chart recorder output.)

73.

Dave G8KBV

 



-- 
Created on and sent from a Unix like PC running and using free and open source software:


Re: Q0-100 Web-SDR 198Hz frequency error

Dave_G0WBX
 

WRT:

From: Gary M1EGI
Date: Tue, 22 Jun 2021 10:33:22 PDT

Hi Andy,

Could some of this be explained by the satellite itself?

Oscillators used, thermal changes onboard due to activity on the main payload?

Just a thought.


Plus the bird itself is not in a true fixed point (WRT the ground stations).

If it's part of a cluster in particular it will move around, I think in a 24 hour cycle.

What does the unexpected offset show 12 hours later, if some 200Hz the other way, maybe that's the cause?

This was explained to me some years ago, by one of the site guys we worked with, when involved with a new DBS uplink install that we were providing the TX PA's for.   But I don't remember the sort of figures he illustrated things with, but the frequencies used were in the 12 GHz area.

(That, as a result of a question I asked, relating to why the antenna positioners kept whirring every few minutes, if the satellite was in a "geostationary" orbit.   That resulted in a good 45 minutes very interesting diversion from amplifier problems, and a visit to one other much older uplink facility on the same site, to see a chart recorder output.)

73.

Dave G8KBV

 



-- 
Created on and sent from a Unix like PC running and using free and open source software:


Re: Handy solution for 10GHz?

Maarten PA0MHE
 

Gareth, I feed 8 volt (~50mA) to pins 3, 5 and13 of the 20v connector, and 6.5V (~1.3A) to pin 11 (internally in the RF module the buck is short circuited). I'm not sure if 6.5V is the right value but in this way the MMIC is supplied with about 5V, The 6.5V is made out of 12V by an Ebay Buck on my PCB.
I didn't do the testing of my own PCB yet as I didn't yet receive the naked PCB from JLCPCB yet, but this is in transit. I have a PCB spare if you are interested ?
So no any RX testing yet. TX testing resulted in a little bit less than 1 Watt output.
73's Maarten


Re: Does anyone recognize this?

Mike Willis
 

Hard to tell if it is a Ku band or a Ka band LNB. How large are the pipes? It's probably a DRO and looks like a dual satellite unit.
--
Mike G0MJW


Bought a couple to evaluate

Stefan
 


Re: Horn for 3.4GHz

dave G8SFU
 

If the rules are the same as in our house the boss would say that should go on a skip. My stock answer is "stop swearing".
We don't use the sk.. word here.

If the parts are useful they should be used.

Regards.  Dave.   Sfu

Sent from BlueMail

On 22 Jun 2021, at 18:38, Colin Ranson <g8lbs@...> wrote:

Dave, just retired a big triple toaster, its in the loft.....wonder if the missus will miss it ?

 

73’s   Colin.

 

Sent from Mail for Windows 10

 

From: dave G8SFU via groups.io
Sent: 22 June 2021 16:13
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Horn for 3.4GHz

 

Also worth a look at toaster element supports. Often about 5inches square.

Dave g8sfu

Sent from BlueMail

On 22 Jun 2021, at 14:53, Raymond Brooks <g8kps@...> wrote:

For Sheet mica look at microwave oven spears.

 

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of KENT BRITAIN
Sent: 22 June 2021 13:09
To: UKMicrowaves@groups.io; UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Horn for 3.4GHz

 

Hi Colin

 

I usually put the window between the horn and the WG Transition.    Much smaller piece and it's out of the weather.

I like to use a sheet of Mica, but that's for X-Band and higher.  Hard to find Mica sheet big enough for 9cm but the bits for the larger power transistors is OK 

 

 

Andy

 

 

 

On Tue, 22 Jun 2021 at 08:28, Gareth G4XAT via groups.io <g4xat=ntlworld.com@groups.io> wrote:

My local repeater GB3JV (DATV) (Petts Wood SE London) is pretty much LOS to me at home, so rather than tie up my Titanium PLL LNB I picked up a NOS Nortel DRO commercial unit. As it needs some form of weather protection I thought I might as well add some gain too. Using this software https://www.raytechx.com/antenna-calc I then designed a 3-D printed 10dBd horn, which came out like the picture. Interior surface finish has been improved by flat filing and I will then cover with aluminium tape. 
A couple of questions....
1. It seems very 'wide' compared to horns I've seen on 10GHz stuff - maybe why its 'only' 10dBd.
2. I have some PTFE sheet, would this be suitable as a gasket to keep the weather out of the LNB cavity, if not would HDPE from a milk carton work?
The horn sizes very quickly got very large (longer print time/too big for the printer) if I upped the target gain figure. I was surprised by this...not like adding a couple of elements to a yagi....
Comments welcome...
Gareth

 


--
Raymond G8KPS

 

1961 - 1980 of 64943