Date   
Re: Sun noise sanity check please

John Lemay
 

Neil

I've not used EME Calc extensively, but when I have my results are believable (ie a dB or so below what is predicted). I've just downloaded the current SFI data and the 10.7cms solar flux is 96. That is well adrift from your findings so presumably one of us is wrong - it could be me !

I do note that the downloaded value is highlighted in red - "values in red indicate extrapolated data which may not be reliable".

Hopefully more experienced ops here can help out.

John G4ZTR

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 27 August 2019 18:09
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Sun noise sanity check please

I just measured 4.6dB of sun noise in a 10kHz bandwidth compared with a
patch of cold sky. I can't make sense of the results I am seeing.

Setup is a 0.85 x 0.95 offset steel pierced dish with f/d about 0.6 and
a WA6KBL linear horn feed optimised for f/d 0.6

Waveguide feed about 1m total into a waveguide relay, then a Kuhne
waveguide EME LNA with 0.9dB NF.

I make the current 10.7cm SFI to be 67. Putting that all into EMECalc,
I seem to be getting slightly better than the theoretical maximum, so I
must be doing something wrong. Ground to cold sky is about 2dB, although
I haven't integrated that for a long enough time.

I got very similar results from the SDR IF display and from my Fluke and
HP thermal millivoltmeters on the audio output. ALso very similar when
I use the SDR calculation in SW2 to measure the time-averages noise
floor at 150kHz bandwidth (using the dBm/Hz value).

Is there somehting I'm doing wrong with EMECalc values? Is the SFI
value not 67? The sun was behind thinnish clouds at the time, would that
mess things up wiht the measurements?

Key issue is that if I'm more than a dB or so worse than it should be,
I'll do more fiddling, otherwise I don't want to mess!

Neil G4DBN

Sun noise sanity check please

Neil Smith G4DBN
 

I just measured 4.6dB of sun noise in a 10kHz bandwidth compared with a patch of cold sky.  I can't make sense of the results I am seeing.

Setup is a 0.85 x 0.95 offset steel pierced dish with f/d about 0.6 and a WA6KBL linear horn feed optimised for f/d 0.6

Waveguide feed about 1m total into a waveguide relay, then a Kuhne waveguide EME LNA with 0.9dB NF.

I make the current 10.7cm SFI to be 67.  Putting that all into EMECalc, I seem to be getting slightly better than the theoretical maximum, so I must be doing something wrong. Ground to cold sky is about 2dB, although I haven't integrated that for a long enough time.

I got very similar results from the SDR IF display and from my Fluke and HP thermal millivoltmeters on the audio output.  ALso very similar when I use the SDR calculation in SW2 to measure the time-averages noise floor at 150kHz bandwidth (using the dBm/Hz value).

Is there somehting I'm doing wrong with EMECalc values?  Is the SFI value not 67? The sun was behind thinnish clouds at the time, would that mess things up wiht the measurements?

Key issue is that if I'm more than a dB or so worse than it should be, I'll do more fiddling, otherwise I don't want to mess!

Neil G4DBN

Re: Tantalum Caps

Clive Jenner
 

Back in the day when I was a test engineer for STC/ITT mobile radio at Peal Road Croydon. I nearly lost an eye to a bead tant that exploded in my face. All I got from the development engineers upstairs was , we should have specified a higher voltage device. I have always kept this in mind when replacing tant caps!

73 Clive GW0PPO

Re: Dial-a-crystal

Robert G8RPI
 


"leaded crystals" could get you a set of glasses and a decanter........

Re: Tantalum Caps

Robert G8RPI
 

The recycling centre will just put them in with everything else. Send them to a specialist refinery. I use AWA Refiners Ltd
https://www.awarefiners.co.uk/precious-metals.php
If you have enough they ill even collect and give you money. Last collection of scrap PCBs I sent them got me £240 and that was after all the useful components (including metal cased tantalums) were removed.

Robert G8RPI.

Re: Tantalum Caps

John Worsnop
 

Tantalum is a seriously scarce resource and the mining if it in some countries is nothing short of an international disgrace. 

To quote "Nature".. doi:10.1038/nature.2015.19023


"Tantalum is a 'conflict mineral', meaning that its sale may be directly financing armed conflict"


Take all your tantalum capacitors down to your local recycling centre, now.

73 John

On Mon, 26 Aug 2019, 00:43 Chris Bartram G4DGU, <chris@...> wrote:
I agree with Gordon. Tantalum capacitors are a devil's invention, and
should be consigned to history. With the coming of high value ceramic
capacitors at reasonable prices, I haven't designed tantalum capacitors
into a work project for over a decade.

73

Chris G4DGU

--
Chris Bartram
Luxulyan, Bodmin, Cornwall
07545 094490
chris@...




Re: Tantalum Caps

Robert G8RPI
 

Dry Tantalum capacitors do give problems, but the wet ones which are a metallic bolt down disc or metallic tubular are pretty reliable. Not all metallic tubular tantalum capacitors are wet, but even the dry tubular ones seem to be better than the dipped or moulded ones. Unless there is a few ohms of fixed impedance in series with a dipped or moulded capacitor or it is significantly over specified for voltage it's likely to be unreliable.

Robert G8RPI.

47 ghz EME in VK6

Keith
 

No this isnt a joke or a late april fools comment :)
I displayed an NEC Pasolink 50 ghz unit at our main VK6 Hamfest yesterday and was amazed by the interest ( at least 8-10 people )
Normally getting anyone in VK6 above 2 mtrs is an impossibility.
Almost all asked, well what about EME on those "funny frequencies"
It got me thinking that maybe our VK6 Microwave group should attempt to acquire the gear to do something about this.
Slowly as I imagine as the group funds will just about stretch to a Kuhne transverter at the moment.
I had a brief chat with Al W5LUA and it seems this band is very neglected ( probably rightly so ;)  ) so maybe we can accumulate the gear and possibly offer a Oceania contact for those who eventually graduate higher.
I know this is all pie in the sky stuff at present, but there are about 5-6 amateurs with exceptional skills here who could do this IF we could get some power on the band.
I certainly dont have the abilities to make the gear, but I'm a pretty good catalyst to get others going ;)
We do have minimal test gear, but I have some HP mixers etc that will get my 24 ghz power meter / Freq counter up to 50 ghz.
The reason for the message is, where can we find power on this band ?
TWT's possibly, so thats what I'm asking here for, if any come up we will be interested if you can pass on the info if you find it.
Dishes, no problems, as we have a very accurate profile 2.2 mtr dish and access to several others of varying sizes.
Feeds we can machine, we will soon have waveguide switches so the stumbling block will be POWER :(
The same problem we face on 10 and 24 ghz here in Australia, there are no sources :(
Keep us in mind please 
73
Keith, Larry and Dean, members of VK6µW ( VK6UW ) the VK6 Microwave Group



Re: Activity List for the UK Microwave Group 5.7Ghz and 10GHz contests - Sunday 25th August

John Lemay
 

Denis

 

We missed you ……….

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of G3UVR Denis via Groups.Io
Sent: 25 August 2019 09:39
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Activity List for the UK Microwave Group 5.7Ghz and 10GHz contests - Sunday 25th August

 

Hello all.. Change of circumstances here. I am sorry I will not be able to operate on 3cm today. I have the daughter visiting and I have had to move my 3cm equipment from her room. Other bands are not affected.  will be back on 3cm Monday evening.

73 de Denis G3UVR

Re: Found my horrible TX signal fault, but...

PAUL NICKALLS
 

We were looking out for you.

73
Paul G8AQA  (G3XME/P)

On 25/08/2019 14:48, Neil Smith G4DBN wrote:
Looks like I won't be operating on 10GHz today, my TX signal out of the masthead transverter is clean, but I have a comb of 15kHz-spaced carriers from amplitude modulation of the signal.  I suispect it could be a fault in the bias circuit in the PA.  With the PA bypassed, everything is OK, but with it in circuit, the +-15kHz carriers are at -14dBc at any power level, and there is a comb out to several hundred kHz.

Of course, the PA is right at the bottom of the enclosure, so it means a total dismantle to get at it.

Does anyone have the bias/control circuit for a PE1RKI 10GHz PA to hand?  I'll drop Bert a line to see if he has one.  I will take the opportunity to make some cooling improvements so not sure if I'll be back on for Tuesday UKAC.

Neil




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Re: Found my horrible TX signal fault, but...

John Worsnop
 

Ah. Tantalums! 
Same thing happened to GB3CAM/24 a few years ago.
 I've recycled all my tantalums at the local waste place. The stuff is getting rare!

73 John

On Sun, 25 Aug 2019, 22:48 Neil Smith G4DBN, <neil@...> wrote:

Found the problem.  Magic smoke had leaked out of a 2.2uF capacitor on the input side of the LT1083C LDO. Capacitance was rather less than spec.  About 2.2 uF less in fact.

Installed a new cap and all looks good again.  Now I just have to rebuild the entire thing, give it a good soak test and and get it mounted on the new az-el dish.  Then I have to get that all collimated and aligned, but at least it is easy now I can point at the sun for calibration anytime it is up.

Neil G4DBN

On 25/08/2019 14:48, Neil Smith G4DBN wrote:
Looks like I won't be operating on 10GHz today, my TX signal out of the masthead transverter is clean, but I have a comb of 15kHz-spaced carriers from amplitude modulation of the signal.  I suispect it could be a fault in the bias circuit in the PA.  With the PA bypassed, everything is OK, but with it in circuit, the +-15kHz carriers are at -14dBc at any power level, and there is a comb out to several hundred kHz.

Re: Tantalum Caps

Paul G8KFW
 

Hi Chris

We should go for a drink in the Pub on my next visit as I visit about 3
times a year

Are you talking about the tantalum capacitors in a metal tube or the ones in
the shape of as bead?

Regards Paul

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of
Chris Bartram G4DGU
Sent: 26 August 2019 00:44
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Tantalum Caps

I agree with Gordon. Tantalum capacitors are a devil's invention, and
should be consigned to history. With the coming of high value ceramic
capacitors at reasonable prices, I haven't designed tantalum capacitors
into a work project for over a decade.

73

Chris G4DGU

--
Chris Bartram
Luxulyan, Bodmin, Cornwall
07545 094490
chris@...







-----
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Checked by AVG - www.avg.com
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Internal Virus Database is out of date.



--
Paul Bicknell G8KFW   South Coast UK

Tantalum Caps

Chris Bartram G4DGU
 

I agree with Gordon. Tantalum capacitors are a devil's invention, and should be consigned to history. With the coming of high value ceramic capacitors at reasonable prices, I haven't designed tantalum capacitors into a work project for over a decade.

73

Chris G4DGU

--
Chris Bartram
Luxulyan, Bodmin, Cornwall
07545 094490
chris@...

Re: Narda Relay help - oops forgot to atache the photos

simonchettle
 

Hi Geoff
 
 
Thanks for the reply – had a good look for a screw but no luck however will try heating the cover.
Cheers
Simon
 
 
 
 

From: geoffrey pike via Groups.Io
Sent: Sunday, August 25, 2019 4:33 PM
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Narda Relay help - oops forgot to atache the photos
 
The black covers are "usually" glued onto the sma base. So heat here and it should melt the glue and it will pull off.
Sometimes there is a screw that needs to be removed
cheers
Geoff
GI0GDP
 
On Sunday, 25 August 2019, 16:20:57 BST, simonchettle <simon@...> wrote:
 
 
 

Re: Found my horrible TX signal fault, but...

Gordon REASON
 

Great thing , Tantalums ,,, should come with a couple of protections diodwes across them .................

On 25 August 2019 at 22:48 Neil Smith G4DBN <neil@...> wrote:

Found the problem.  Magic smoke had leaked out of a 2.2uF capacitor on the input side of the LT1083C LDO. Capacitance was rather less than spec.  About 2.2 uF less in fact.

Installed a new cap and all looks good again.  Now I just have to rebuild the entire thing, give it a good soak test and and get it mounted on the new az-el dish.  Then I have to get that all collimated and aligned, but at least it is easy now I can point at the sun for calibration anytime it is up.

Neil G4DBN

On 25/08/2019 14:48, Neil Smith G4DBN wrote:
Looks like I won't be operating on 10GHz today, my TX signal out of the masthead transverter is clean, but I have a comb of 15kHz-spaced carriers from amplitude modulation of the signal.  I suispect it could be a fault in the bias circuit in the PA.  With the PA bypassed, everything is OK, but with it in circuit, the +-15kHz carriers are at -14dBc at any power level, and there is a comb out to several hundred kHz.


 


 

Re: Found my horrible TX signal fault, but...

Neil Smith G4DBN
 

Found the problem.  Magic smoke had leaked out of a 2.2uF capacitor on the input side of the LT1083C LDO. Capacitance was rather less than spec.  About 2.2 uF less in fact.

Installed a new cap and all looks good again.  Now I just have to rebuild the entire thing, give it a good soak test and and get it mounted on the new az-el dish.  Then I have to get that all collimated and aligned, but at least it is easy now I can point at the sun for calibration anytime it is up.

Neil G4DBN

On 25/08/2019 14:48, Neil Smith G4DBN wrote:
Looks like I won't be operating on 10GHz today, my TX signal out of the masthead transverter is clean, but I have a comb of 15kHz-spaced carriers from amplitude modulation of the signal.  I suispect it could be a fault in the bias circuit in the PA.  With the PA bypassed, everything is OK, but with it in circuit, the +-15kHz carriers are at -14dBc at any power level, and there is a comb out to several hundred kHz.

Re: Question about 26 Ghz HP VNA

Paul G8KFW
 

Hi Dave thank you

I realise your VNA only goes to  20 Ghz  that is why I didn’t ask you this morning

Before a went back to sleep again

 

Regards Paul

 


From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dr. David Kirkby from Kirkby Microwave Ltd
Sent: 25 August 2019 17:39
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Question about 26 Ghz HP VNA

 

On Sun, 25 Aug 2019 at 17:31, Paul Bicknell <paul@...> wrote:

Hi all

dues any one have a HP  VNA that works at 26 Ghz  as I would like to talk about it  please com back to me on paul@... 

Regards Paul

 

There must be loads of people on the HP/Agilent/Keysight list with HP 8510Cs. There is a test set that goes up to 20 GHz, but all the rest go higher, up to at least 110 GHz. My own VNA, an 8720D stops at 20 GHz.

Dave
--
Paul Bicknell G8KFW   South Coast UK
--

Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892
https://www.kirkbymicrowave.co.uk/
Tel 01621-680100 / +44 1621-680100

No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8048 / Virus Database: 4793/15884 - Release Date: 08/14/18
Internal Virus Database is out of date.


--
Paul Bicknell G8KFW   South Coast UK

Re: Question about 26 Ghz HP VNA

Dr. David Kirkby from Kirkby Microwave Ltd <drkirkby@...>
 

On Sun, 25 Aug 2019 at 17:31, Paul Bicknell <paul@...> wrote:

Hi all

dues any one have a HP  VNA that works at 26 Ghz  as I would like to talk about it 

please com back to me on paul@...

 

Regards Paul


There must be loads of people on the HP/Agilent/Keysight list with HP 8510Cs. There is a test set that goes up to 20 GHz, but all the rest go higher, up to at least 110 GHz. My own VNA, an 8720D stops at 20 GHz.

Dave


 


--
Paul Bicknell G8KFW   South Coast UK



--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892
https://www.kirkbymicrowave.co.uk/
Tel 01621-680100 / +44 1621-680100

Question about 26 Ghz HP VNA

Paul G8KFW
 

Hi all

dues any one have a HP  VNA that works at 26 Ghz  as I would like to talk about it 

please com back to me on paul@...

 

Regards Paul

 


--
Paul Bicknell G8KFW   South Coast UK

Re: Found my horrible TX signal fault, but...

Neil Smith G4DBN
 

Hi Denis, all the supplies into the head unit are DC, I feed +14V isolated for the PA (to avoid current loops on the negative return), +13.8V for everything else and +28 for the relays and waveguide switches.  There is a charge pump for th Gasfet bias on the amplifier PCB but it almost looks like there is a protection circuit for loss of bias which is triggering on and off. I've asked Bert for a diagram, but it is too hot for messing about with electronics, and I have a house full of muscly volunteers, so I've got them hauling antennas and masts about the place.

Neil

On 25/08/2019 16:19, G3UVR Denis via Groups.Io wrote:
Hi Neil..

Had the same thing here. Mine was traced to the 6khz power osc doing the 12v to 24v supply to power the relays.. It was the very early G4JNT PCB and there was insufficient decoupling and the 6khz was getting into the other supplies causing carriers every 6k away from the wanted signal.
Only recently found it when I was making up a second system which I initially thought was at fault but it was my main system..

Once found I disconected the power osc supply and use one of the modern buck converters to do the 12v to 28v supply problem sorted.