Date   

Re: New MGM Modes on Beacons

Dominique Dehays
 

Hi all ,


Yes my experiments show a 20 log N increase of spurs.
73
Dom


Re: New MGM Modes on Beacons

Andy G4JNT
 

No, it doesn't work like that.   Visualise the multiplier as a hard limiter or zero crossing detector:

That -30dB 90MHz component adds to the 100MHz signal and periodically shifts the point at which the main 100MHz component crosses the zero threshold, resulting in a jitter on the limited output.  The resulting jitter then reappears as sidebands on the multiplied output.   You have to consider the total input, with spurii, in the time domain.

I can't supply the mathematical proof of the reason for squaring, or why it isn't any other order, but it's certainly there in practice and quite observable.

Andy


On Tue, 16 Mar 2021 at 17:46, Robin Szemeti - G1YFG <robin@...> wrote:
" When the RF is passed through a frequency multiplier these spurii increase in relative amplitude as the square of the multiplication factor"

I found this "interesting" as I would have thought that if you had say 100MHz at 0dBm and 90MHz spur at -30dBm ... and then whacked the signal through a x3 multiplier, by driving some MMIC or similar hard into clipping ... I would have expected the output to be swamped by the 100MHz signal, and the "weak" 90MHz signal to be effectively blocked, and thus removed from the output,  and by the time it had been through the output filter to pick up the 3rd harmonic, I would expect it to look very clean indeed.  I had always assumed that multiplier chains cleaned up the spurs, not made them worse. I shall ponder this further ...


On Tue, 16 Mar 2021 at 16:57, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> wrote:

Alwyn

I have not got hard numbers to hand, but I can compare it with the 23cm beacon, where the beacon is approximately 95dB above noise in 2.5kHz bandwidth and results in a rise in the apparent band noise of 5db when I beam at it on 1296.200. My LO and the beacon oscillator are almost identical, so probably each contributes the same amount of phase noise. I have a crystal notch filter in the 28MHz transverter IF to reduce the beacon signal level by about 50dB going into the K3.

The 13cm beacon is about 10dB weaker, there is no change in band noise at 2320.200 when I beam at it. There are no major spurs in the SSB/CW part of the band, but they are apparent in the beacon band. When we have got it on air again I will make some proper measurements.

73

John G3XDY

On 16/03/2021 13:19, alwyn.seeds1 wrote:
Dear John and Andy,

Getting DDS spurs low enough for beacon use must be quite a challenge. At work, all of our DDS based signal generators, including the pricey ones, have quite a few spurs at the -80 dBc level- the nuisance is that they do not have easily predictable frequencies. We moan to the manufacturers but I have not seen much improvement over the last decade.

John, what sort of phase noise numbers do you get from the GB3MHZ beacon?

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Virus-free. www.avast.com


--
Robin Szemeti - G1YFG


Re: New MGM Modes on Beacons

Robin Szemeti - G1YFG
 

" When the RF is passed through a frequency multiplier these spurii increase in relative amplitude as the square of the multiplication factor"

I found this "interesting" as I would have thought that if you had say 100MHz at 0dBm and 90MHz spur at -30dBm ... and then whacked the signal through a x3 multiplier, by driving some MMIC or similar hard into clipping ... I would have expected the output to be swamped by the 100MHz signal, and the "weak" 90MHz signal to be effectively blocked, and thus removed from the output,  and by the time it had been through the output filter to pick up the 3rd harmonic, I would expect it to look very clean indeed.  I had always assumed that multiplier chains cleaned up the spurs, not made them worse. I shall ponder this further ...


On Tue, 16 Mar 2021 at 16:57, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> wrote:

Alwyn

I have not got hard numbers to hand, but I can compare it with the 23cm beacon, where the beacon is approximately 95dB above noise in 2.5kHz bandwidth and results in a rise in the apparent band noise of 5db when I beam at it on 1296.200. My LO and the beacon oscillator are almost identical, so probably each contributes the same amount of phase noise. I have a crystal notch filter in the 28MHz transverter IF to reduce the beacon signal level by about 50dB going into the K3.

The 13cm beacon is about 10dB weaker, there is no change in band noise at 2320.200 when I beam at it. There are no major spurs in the SSB/CW part of the band, but they are apparent in the beacon band. When we have got it on air again I will make some proper measurements.

73

John G3XDY

On 16/03/2021 13:19, alwyn.seeds1 wrote:
Dear John and Andy,

Getting DDS spurs low enough for beacon use must be quite a challenge. At work, all of our DDS based signal generators, including the pricey ones, have quite a few spurs at the -80 dBc level- the nuisance is that they do not have easily predictable frequencies. We moan to the manufacturers but I have not seen much improvement over the last decade.

John, what sort of phase noise numbers do you get from the GB3MHZ beacon?

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Virus-free. www.avast.com


--
Robin Szemeti - G1YFG


Re: New MGM Modes on Beacons

John Quarmby
 

Alwyn

I have not got hard numbers to hand, but I can compare it with the 23cm beacon, where the beacon is approximately 95dB above noise in 2.5kHz bandwidth and results in a rise in the apparent band noise of 5db when I beam at it on 1296.200. My LO and the beacon oscillator are almost identical, so probably each contributes the same amount of phase noise. I have a crystal notch filter in the 28MHz transverter IF to reduce the beacon signal level by about 50dB going into the K3.

The 13cm beacon is about 10dB weaker, there is no change in band noise at 2320.200 when I beam at it. There are no major spurs in the SSB/CW part of the band, but they are apparent in the beacon band. When we have got it on air again I will make some proper measurements.

73

John G3XDY

On 16/03/2021 13:19, alwyn.seeds1 wrote:
Dear John and Andy,

Getting DDS spurs low enough for beacon use must be quite a challenge. At work, all of our DDS based signal generators, including the pricey ones, have quite a few spurs at the -80 dBc level- the nuisance is that they do not have easily predictable frequencies. We moan to the manufacturers but I have not seen much improvement over the last decade.

John, what sort of phase noise numbers do you get from the GB3MHZ beacon?

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Virus-free. www.avast.com


Re: New MGM Modes on Beacons

alwyn.seeds1
 

Dear John and Andy,

Getting DDS spurs low enough for beacon use must be quite a challenge. At work, all of our DDS based signal generators, including the pricey ones, have quite a few spurs at the -80 dBc level- the nuisance is that they do not have easily predictable frequencies. We moan to the manufacturers but I have not seen much improvement over the last decade.

John, what sort of phase noise numbers do you get from the GB3MHZ beacon?

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Re: New MGM Modes on Beacons

John Quarmby
 

Plenty of food for thought Andy, thank you very much. I'm thinking that upgrading existing beacons to retain low phase noise and spurs might be easiest by using a fixed RDDS for frequency control, with a baseband I/Q modulator driven from a PIC via DACs modulating the output of the RDDS to provide all the modes required.

The 13cm version of GB3MHZ (when it is working!) uses a Next Gen Beacon source running on 320.830MHz with FSK CW and PI4, mixed with 2GHz multiplied from the 1GHz Next Gen clock. Phase noise performance is quite respectable, and in band spurs are just about acceptable here 4km LoS from the beacon.

73

John G3XDY

On 16/03/2021 10:21, Andy G4JNT wrote:

[Edited Message Follows]
[Reason: A pile of silly typos corrected]

With the introduction of new modes within the WSJT-X suite that use Gaussian shift MFSK, the old technique of switching between several switched tones using either a DDS or Fract-N PLL is no longer valid
 
Although not yet really applicable to microwaves, where JT4, JT65/Qxxx and PI4 will continue to reign, it is worth thinking about ways to implement FST4 and FT8/4 ready for if and when new GFSK modes appear that are suited to uWave usage.
 
This paper summarises the situation to date, and suggests a few ways forward.
 
 
 
Andy
 

Virus-free. www.avg.com


New MGM Modes on Beacons

Andy G4JNT
 
Edited

With the introduction of new modes within the WSJT-X suite that use Gaussian shift MFSK, the old technique of switching between several switched tones using either a DDS or Fract-N PLL is no longer valid
 
Although not yet really applicable to microwaves, where JT4, JT65/Qxxx and PI4 will continue to reign, it is worth thinking about ways to implement FST4 and FT8/4 ready for if and when new GFSK modes appear that are suited to uWave usage.
 
This paper summarises the situation to date, and suggests a few ways forward.
 
 
 
Andy
 

Virus-free. www.avg.com


Re: Surplus crystal?

Michael Scott
 

Hi Chris

The Chipbank has some 14.5000MHz if that would help.

73, Mike

On 15/03/2021 16:30, Chris G8BKE wrote:
Slightly off topic and a bit of a long shot but does anyone have a surplus crystal of frequency 14.4975MHz in their surplus stock that they are willing to part with?  HC18/U preferred but can accept HC25/U or HC6/U.
 
Please contact me off list at gmail,  g8bke23 etc
 
 
 
73 de Chris G8BKE
 


Surplus crystal?

Chris G8BKE
 

Slightly off topic and a bit of a long shot but does anyone have a surplus crystal of frequency 14.4975MHz in their surplus stock that they are willing to part with?  HC18/U preferred but can accept HC25/U or HC6/U.
 
Please contact me off list at gmail,  g8bke23 etc
 
 
 
73 de Chris G8BKE
 


Re: Wessex F8401 amplifier #amplifier

G8FXB
 

Hi,

Unmodified they have a gain of about 20dB and NF around 4dB. I replaced all the FETs with MGF4919s on one and CE3512K2-C1 on another. I also converted the 1st stage to single ended. That reduced the NF to <1.4dB and increased the gain to 20-25dB. It also reduced the centre frequency. I didn't bother tweak it after that. 

The bias circuitry is quite fragile, physically and electrically. If you mod. one, be careful you don't damage it. It would be better to replace it with an alternative e.g. one of the Zetex bias controllers.

Regards,
Graham


Re: UKuG branded clothing

Murray Niman
 


Shameless plug and directly link:

https://www.microwavers.org/?accessories.htm 

- and nice UKuG badges still available too

    Murray G6JYB


Re: Last call for group buy of F6BVA QO-100 system PCBs etc

Colin Ranson
 

All,

 

Just a quick throw into the air.  I currently run a lashed up  up-converter from 432MHz to 2400MHz using a SKY-60LH mixer and an ADF4351A LO at 1968MHz – it drifts as it has a crap 25MHz reference crystal.  Some amplification up to 500mW to drive a 20w SG-Lab amp. It needs a lot of improvement. (stable reference <the RX LNB one> and sharp LO filter) Prime mover is an IC-706MK2g – I did use an SG-Lab transverter but a hell of a waste and a pain.

 

RX is down converter from LNB IF 739MHz  to 144MHz (FT480) – steady as Gibraltar. I have been having thoughts about changing the LO in this to 307MHz to give /RX IF of 432MHz to give full simplex on a non satelite equipped radio – ie the 706.

 

Anyone done anything similar ?

 

Regards to all,   Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Neil Smith G4DBN
Sent: 14 March 2021 13:54
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Last call for group buy of F6BVA QO-100 system PCBs etc

 

As previously mentioned, I'm doing a group buy of PCB sets for the F6BVA
QO-100 up/down converter and MW7ic2725 PA.

This version of Michel's design is about making a simple standalone unit
for use over QO-100 without needing a computer or SDR dongle, and
without tying up the TX side of a 13cm transverter. Ideal for a go-box
with a 2m/70cm SSB rig and POTY-equipped dish.

There is already enough interest to do a group purchase of the
components. I will be providing some English-language construction
notes. The set of two PCBs is likely to cost around £40, perhaps a
little less if demand is high enough. Not sure of component cost yet,
but the Minicircuits mixer at £13 and MW7ic2725 at £50-ish are the only
expensive bits.

You'll need a local osc with two selectable frequencies. An SV1AFN or
even a Chinese ADF4350/51 would be good enough for QO-100 usage.

Sorry there isn't a converter-only option as the economics of fancy SHF
laminates and finishes mean we have to buy both boards, but you may be
able to find a home for the PA PCB if you don't need it.

For clarity, the older version was full-duplex, but this V3 is designed
to work with a simple half-duplex transceiver.  On 2m, you can use a
DF9NP LO using one of the control pins, but for the other bands (and
also 2m) you can use an SV1AFN or Chinese ADF4351 with a tx/rx
changeover flipping the frequency via a pin on the controller. I'll be
using an SV1AFN board. Not decided about the controller yet, might just
use an 8-pin PIC and PSU and TCXO on board, but that would just be
reinventing the SV1AFN controller. We'll be supporting this through the
IO group at https://groups.io/g/BVA-transverters-uk/message/356 which
you are welcome to join.

If you are interested, have a look at the document (in French) at
https://f6bva.pagesperso-orange.fr/Technique/Satellite/Station%20V3%20QO100%20complete.pdf

If you'd like to join a group purchase of the PCBs, with optional tin
box, milled aluminium PA box and full or part component set, please
email me direct to neil@... with title QO100 so I don't miss the
message!

I'll be finalising the order to send to Pierre-François in the next day
or two, but the ultimate cut-off will be when he submits the order to
the pcb fab. I don't expect there will be a second tranche.

Neil G4DBN




 


Last call for group buy of F6BVA QO-100 system PCBs etc

Neil Smith G4DBN
 

As previously mentioned, I'm doing a group buy of PCB sets for the F6BVA QO-100 up/down converter and MW7ic2725 PA.

This version of Michel's design is about making a simple standalone unit for use over QO-100 without needing a computer or SDR dongle, and without tying up the TX side of a 13cm transverter. Ideal for a go-box with a 2m/70cm SSB rig and POTY-equipped dish.

There is already enough interest to do a group purchase of the components. I will be providing some English-language construction notes. The set of two PCBs is likely to cost around £40, perhaps a little less if demand is high enough. Not sure of component cost yet, but the Minicircuits mixer at £13 and MW7ic2725 at £50-ish are the only expensive bits.

You'll need a local osc with two selectable frequencies. An SV1AFN or even a Chinese ADF4350/51 would be good enough for QO-100 usage.

Sorry there isn't a converter-only option as the economics of fancy SHF laminates and finishes mean we have to buy both boards, but you may be able to find a home for the PA PCB if you don't need it.

For clarity, the older version was full-duplex, but this V3 is designed to work with a simple half-duplex transceiver.  On 2m, you can use a DF9NP LO using one of the control pins, but for the other bands (and also 2m) you can use an SV1AFN or Chinese ADF4351 with a tx/rx changeover flipping the frequency via a pin on the controller. I'll be using an SV1AFN board. Not decided about the controller yet, might just use an 8-pin PIC and PSU and TCXO on board, but that would just be reinventing the SV1AFN controller. We'll be supporting this through the IO group at https://groups.io/g/BVA-transverters-uk/message/356 which you are welcome to join.

If you are interested, have a look at the document (in French) at https://f6bva.pagesperso-orange.fr/Technique/Satellite/Station%20V3%20QO100%20complete.pdf

If you'd like to join a group purchase of the PCBs, with optional tin box, milled aluminium PA box and full or part component set, please email me direct to neil@g4dbn.uk with title QO100 so I don't miss the message!

I'll be finalising the order to send to Pierre-François in the next day or two, but the ultimate cut-off will be when he submits the order to the pcb fab. I don't expect there will be a second tranche.

Neil G4DBN


Re: SHF Brolly (tks F1VL)

Neil Smith G4DBN
 

Just like me really. If a thing is worth doing, then it's worth over-doing.  The borderlines between radio engineering, jewellery-making and art sculpture narrow daily.

Neil G4DBN

On 14/03/2021 11:31, militaryoperator via groups.io wrote:
I think a chunky CNC milling machine would be a MUCH better investment though.  Then I could make stuff like Tauss does - lovely milled aluminium case for an ADALM Pluto with swoopy sides https://pbs.twimg.com/media/EwVVb5fVkAEyHk4?format=jpg&name=large


Looks like he's just trying to find things to do with that nice big CNC machine! Slightly overkill? 

Ben


Re: SHF Brolly (tks F1VL)

militaryoperator
 

I think a chunky CNC milling machine would be a MUCH better investment though.  Then I could make stuff like Tauss does - lovely milled aluminium case for an ADALM Pluto with swoopy sides https://pbs.twimg.com/media/EwVVb5fVkAEyHk4?format=jpg&name=large


Looks like he's just trying to find things to do with that nice big CNC machine! Slightly overkill? 

Ben


Re: SHF Brolly (tks F1VL)

Neil Smith G4DBN
 

On 14/03/2021 10:25, militaryoperator via groups.io wrote:

Apparently Neil, $1780 for 1.8 dish and 23m feed shipped to Uk. $280 is for post so $1500 for goods. 

I know there's a bit of engineering in the tensioning system, though just like a brolly, but seems a lot, £1077. 

Mind you, on another FB page someone was saying they just paid £120 for a premade Windom aerial! and that's just a bit of wire. Then there's that bit of wire in a long thin bag that you can buy for £90 odd and you stick a plastic pole up the bag center to make a verticle. 

I'm in the wrong game, hi, well not any game these days. 

I don't mind folks making a living out of selling stuff. If they can find customers willing to pay, then go for it.  We should make QSLs into Non-Fungible Tokens and start a secondary market in them. Hamcoin sounds a good plan as well.

I can see the attraction of that antenna for folks who can't operate from home or only have a tiny space, and who are working full time and don't have the facilities to make stuff. I prefer to waste my pocket-money on machine tools and testgear so I can make stuff, but I know a lot of amateurs who get huge pleasure from buying nice things and operating them.  I'm just one of those hams who doesn't actually enjoy talking to strangers on the radio, so making and testing and modifying stuff is what I like to do.

Still, if I didn't have a motorhome and trailer for /P stuff, I could see myself saving up the pennies for one of these brollies. Bit of a bugger trying to get any other 1.8m dish in a saloon car, especially one without a towbar.

I think a chunky CNC milling machine would be a MUCH better investment though.  Then I could make stuff like Tauss does - lovely milled aluminium case for an ADALM Pluto with swoopy sides https://pbs.twimg.com/media/EwVVb5fVkAEyHk4?format=jpg&name=large

Neil G4DBN




Wessex F8401 amplifier #amplifier

am.andrej@...
 

Hi,

I'm looking for any information about Wessex F8401 amplifier. 7.85GHz-8.45GHz
Power supply range, NF and gain?
Maybe useful for DSN system as LNA ..need some info before buy it from allegro.

thanks info

73 de Andrej


MGM Beacon History

Andy G4JNT
 

Would I be right in thinking GB3VHF was the first permanent beacon to adopt any of the WSJT modes?    It certainly was in the UK, coz, ahem, yours-truly built the driver for it.

That was in 2005 and initially the mode was to have been JT44, then changed to JT65 as that mode had just appeared.

What I'm wondering, is if there were any others in the World that were earlier?


Re: SHF Brolly (tks F1VL)

militaryoperator
 

Subject: Re: [UKMicrowaves] SHF Brolly (tks F1VL)

I guess approximately $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Neil
On 13/03/2021 20:49, militaryoperator via groups.io wrote:
No prices on their website !!

Ben
---------------------------

Apparently Neil, $1780 for 1.8 dish and 23m feed shipped to Uk. $280 is for post so $1500 for goods. 

I know there's a bit of engineering in the tensioning system, though just like a brolly, but seems a lot, £1077. 

Mind you, on another FB page someone was saying they just paid £120 for a premade Windom aerial! and that's just a bit of wire. Then there's that bit of wire in a long thin bag that you can buy for £90 odd and you stick a plastic pole up the bag center to make a verticle. 

I'm in the wrong game, hi, well not any game these days. 

Ben


Re: UKuG branded clothing

John E. Beech
 

"polo shorts" are no good to me - I haven't got a horse! Unless they are swimming trunks for the other polo game. I
guess you mean "shirts", but spell checkers don't high-light those sort of mistakes

-------Original Message-------
From: Chris G0FDZ <chris@g0fdz.com>
To: UK microwaves <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] UKuG branded clothing
Sent: Mar 14 '21 07:12

Hi folks

Just a  reminder that the details of how to obtain the UKuG branded
clothing (polo shorts and fleeces) can now be found at the bottom of the
front page of the UKuG website in the 'Badges, Clothing and Accessories'
section.

Regards

Chris G0FDZ


--
This email has been checked for viruses by AVG.
https://www.avg.com






2481 - 2500 of 64039