Date   

Re: 6cm tests

militaryoperator
 



try ERA-1 maybe
Chris


only about 8db gain at 6Ghz, so maybe two in series?

Ben


Re: 6cm tests

Chris G0WUS
 

try ERA-1 maybe

Chris


On 08/05/2021 12:42, militaryoperator via groups.io wrote:
oh yes Simon, but as many will say, its the fun of it !!!!!

I thought I';d better see if those SPF boards do work somewhere, on 2mtrs its 23db gain so I guess I'll not be throwing them away yet. Guess 6Ghz was asking a lot!

Tried some Avantek modules, marked 2.7 to 3.3Ghz 12v and they are good, 23db at 2.4 with 200mw o/p at 0dbm in. I must try and find a use for them. 

Ben. G4BXD




Subject: Re: [UKMicrowaves] 6cm tests

I had a similar experience yesterday on 13cm, LO ADF4351, mixer ADL5350, LNA SPF5189, bi-quad antenna, Sky 60cm dish. I could barely make out GB3FNM at 25km.

As this is my first attempt at microwave frequencies I don't really know what to expect. The path to FNM was nearly line of sight but not quite.

Still it's a start.

Simon
G0FCU.

On Sat, 8 May 2021, 10:19 militaryoperator via groups.io, <Military1944=aol.com@groups.io> wrote:
Well, that was a waste of several hours of my life. 

Tried using one of the SPF5189  devices into first a ADL5350 mixer and then a Anaren dbl bal mixer 2.5 to 10Ghz, using the ADF osc as the lo. I can see 5.760 from the sig gen on the SDRConsole with RSP2 but could not see OHM in B'ham but I was only using an LPA on its own.

I see ebay has some similar boards marked as upto 6ghz but does not state device, probably the same as above with a different printed cover! At £6.68 guess a punt will not kill me. 

Whilst all the stuff was out re-tried these supposed 1W amps for 2.4, RF2126 devices, what a croc. Best was 150mw o/p at 2.4 which rose to 300mw at 2.3, obviously, the matching etc is not right I guess. Pity, its a nice pcb but I guess I win a nice heatsink though. 

So, back to the drawing board. 

Ben. 


Re: 6cm tests

militaryoperator
 

oh yes Simon, but as many will say, its the fun of it !!!!!

I thought I';d better see if those SPF boards do work somewhere, on 2mtrs its 23db gain so I guess I'll not be throwing them away yet. Guess 6Ghz was asking a lot!

Tried some Avantek modules, marked 2.7 to 3.3Ghz 12v and they are good, 23db at 2.4 with 200mw o/p at 0dbm in. I must try and find a use for them. 

Ben. G4BXD




Subject: Re: [UKMicrowaves] 6cm tests

I had a similar experience yesterday on 13cm, LO ADF4351, mixer ADL5350, LNA SPF5189, bi-quad antenna, Sky 60cm dish. I could barely make out GB3FNM at 25km.

As this is my first attempt at microwave frequencies I don't really know what to expect. The path to FNM was nearly line of sight but not quite.

Still it's a start.

Simon
G0FCU.

On Sat, 8 May 2021, 10:19 militaryoperator via groups.io, <Military1944=aol.com@groups.io> wrote:
Well, that was a waste of several hours of my life. 

Tried using one of the SPF5189  devices into first a ADL5350 mixer and then a Anaren dbl bal mixer 2.5 to 10Ghz, using the ADF osc as the lo. I can see 5.760 from the sig gen on the SDRConsole with RSP2 but could not see OHM in B'ham but I was only using an LPA on its own.

I see ebay has some similar boards marked as upto 6ghz but does not state device, probably the same as above with a different printed cover! At £6.68 guess a punt will not kill me. 

Whilst all the stuff was out re-tried these supposed 1W amps for 2.4, RF2126 devices, what a croc. Best was 150mw o/p at 2.4 which rose to 300mw at 2.3, obviously, the matching etc is not right I guess. Pity, its a nice pcb but I guess I win a nice heatsink though. 

So, back to the drawing board. 

Ben. 


Re: 6cm tests

Andy G4JNT
 

Take a look at the datasheet for the SPF5189.   You'll see that although it is "specified" for use up to 4GHz, none of the RF specs that are listed of graphed are specified above 2.2GHz

The only indication of activity above 2.2GHz is seen in the " GMAX versus Frequency" curve on page 7 which suggests gain has dropped to ~ 8.5dB at 3.4GHz

Note also how in  " Typical RF Performance " on Page 2 of the DS, how the noise figure jumps from 0.91 at 2.1GHz to 0.98 at 2.2GHz

That may be a clue to why you are seeing poor performance; the NF may well be terrible at 3.4GHz and there's not much gain to overcome mixer loss




On Sat, 8 May 2021 at 12:24, G0FCU <simon@...> wrote:
I had a similar experience yesterday on 13cm, LO ADF4351, mixer ADL5350, LNA SPF5189, bi-quad antenna, Sky 60cm dish. I could barely make out GB3FNM at 25km.

As this is my first attempt at microwave frequencies I don't really know what to expect. The path to FNM was nearly line of sight but not quite.

Still it's a start.

Simon
G0FCU.

On Sat, 8 May 2021, 10:19 militaryoperator via groups.io, <Military1944=aol.com@groups.io> wrote:
Well, that was a waste of several hours of my life. 

Tried using one of the SPF5189  devices into first a ADL5350 mixer and then a Anaren dbl bal mixer 2.5 to 10Ghz, using the ADF osc as the lo. I can see 5.760 from the sig gen on the SDRConsole with RSP2 but could not see OHM in B'ham but I was only using an LPA on its own.

I see ebay has some similar boards marked as upto 6ghz but does not state device, probably the same as above with a different printed cover! At £6.68 guess a punt will not kill me. 

Whilst all the stuff was out re-tried these supposed 1W amps for 2.4, RF2126 devices, what a croc. Best was 150mw o/p at 2.4 which rose to 300mw at 2.3, obviously, the matching etc is not right I guess. Pity, its a nice pcb but I guess I win a nice heatsink though. 

So, back to the drawing board. 

Ben. 


Re: 6cm tests

G0FCU
 

I had a similar experience yesterday on 13cm, LO ADF4351, mixer ADL5350, LNA SPF5189, bi-quad antenna, Sky 60cm dish. I could barely make out GB3FNM at 25km.

As this is my first attempt at microwave frequencies I don't really know what to expect. The path to FNM was nearly line of sight but not quite.

Still it's a start.

Simon
G0FCU.

On Sat, 8 May 2021, 10:19 militaryoperator via groups.io, <Military1944=aol.com@groups.io> wrote:
Well, that was a waste of several hours of my life. 

Tried using one of the SPF5189  devices into first a ADL5350 mixer and then a Anaren dbl bal mixer 2.5 to 10Ghz, using the ADF osc as the lo. I can see 5.760 from the sig gen on the SDRConsole with RSP2 but could not see OHM in B'ham but I was only using an LPA on its own.

I see ebay has some similar boards marked as upto 6ghz but does not state device, probably the same as above with a different printed cover! At £6.68 guess a punt will not kill me. 

Whilst all the stuff was out re-tried these supposed 1W amps for 2.4, RF2126 devices, what a croc. Best was 150mw o/p at 2.4 which rose to 300mw at 2.3, obviously, the matching etc is not right I guess. Pity, its a nice pcb but I guess I win a nice heatsink though. 

So, back to the drawing board. 

Ben. 


6cm tests

militaryoperator
 

Well, that was a waste of several hours of my life. 

Tried using one of the SPF5189  devices into first a ADL5350 mixer and then a Anaren dbl bal mixer 2.5 to 10Ghz, using the ADF osc as the lo. I can see 5.760 from the sig gen on the SDRConsole with RSP2 but could not see OHM in B'ham but I was only using an LPA on its own.

I see ebay has some similar boards marked as upto 6ghz but does not state device, probably the same as above with a different printed cover! At £6.68 guess a punt will not kill me. 

Whilst all the stuff was out re-tried these supposed 1W amps for 2.4, RF2126 devices, what a croc. Best was 150mw o/p at 2.4 which rose to 300mw at 2.3, obviously, the matching etc is not right I guess. Pity, its a nice pcb but I guess I win a nice heatsink though. 

So, back to the drawing board. 

Ben. 


Re: QRP PA devices for 10 GHz

Neil Smith G4DBN
 

Price with tax, delivery duty paid was £40.60 each for ten-off from Digikey.  No need for an EAR declaration.

Neil G4DBN

On 07/05/2021 22:10, Neil Smith G4DBN wrote:

HMC952A looks reasonable at around £37 plus tax at Mouser and £34 at Digikey in 10-off Cheaper from Arrow/Richardson RFPD, but DK/Mouser deal with UK import VAT, saving customs fees. I just bought ten in case they decide to go on back order adn 52 week delivery, like some parts.

https://www.digikey.co.uk/product-detail/en/analog-devices-inc/HMC952ALP5GE/1127-3364-ND/5813138

https://www.mouser.co.uk/datasheet/2/609/HMC952A-972562.pdf

35 dBm saturated , P1dB 32 dBm, and over 30dB gain at 10368 MHz internally matched and with a power detector. Needs negative bias and interlocks for bias loss, overcurrent, and needs a temperature monitor. Power is +6V at 1400 mA quiescent and 2 A flat out.  The PCB needs to shift heat well, the pad is 3 x 3 mm and needs to lose 10 watts,  Thermal resistance is already pretty high, so cooling is a serious challenge, even if the PCB has lots of vias under that pad and it is soldered to a copper case or spreader.

There are still some gasfet devices around, but of the current crop of non-obsolete parts, this one looks to be best value. HMC487 is lower power, lower gain and double the price for no obvious benefit.

Neil G4DBN

On 07/05/2021 21:36, Greg - ZL3IX wrote:
We've recently seen a couple of posts on this group about higher power (and expensive) PA devices, but what are guys using for the lower powers, maybe 0.5 - 2W? Are there devices around for a more reasonable price? I'm making fair progress with my home brew transverter for 10 GHz, and the next stage will be to produce a little power on the band. ideas?
-- 
Neil
http://g4dbn.uk


Re: QRP PA devices for 10 GHz

Neil Smith G4DBN
 

HMC952A looks reasonable at around £37 plus tax at Mouser and £34 at Digikey in 10-off Cheaper from Arrow/Richardson RFPD, but DK/Mouser deal with UK import VAT, saving customs fees. I just bought ten in case they decide to go on back order adn 52 week delivery, like some parts.

https://www.digikey.co.uk/product-detail/en/analog-devices-inc/HMC952ALP5GE/1127-3364-ND/5813138

https://www.mouser.co.uk/datasheet/2/609/HMC952A-972562.pdf

35 dBm saturated , P1dB 32 dBm, and over 30dB gain at 10368 MHz internally matched and with a power detector. Needs negative bias and interlocks for bias loss, overcurrent, and needs a temperature monitor. Power is +6V at 1400 mA quiescent and 2 A flat out.  The PCB needs to shift heat well, the pad is 3 x 3 mm and needs to lose 10 watts,  Thermal resistance is already pretty high, so cooling is a serious challenge, even if the PCB has lots of vias under that pad and it is soldered to a copper case or spreader.

There are still some gasfet devices around, but of the current crop of non-obsolete parts, this one looks to be best value. HMC487 is lower power, lower gain and double the price for no obvious benefit.

Neil G4DBN

On 07/05/2021 21:36, Greg - ZL3IX wrote:
We've recently seen a couple of posts on this group about higher power (and expensive) PA devices, but what are guys using for the lower powers, maybe 0.5 - 2W? Are there devices around for a more reasonable price? I'm making fair progress with my home brew transverter for 10 GHz, and the next stage will be to produce a little power on the band. ideas?
_._,_._,_



Re: Narda attenuator

 

Here is one of the type you refer to: appears to have 6 attenuator sections, 5 pi and one T (for some reason!) 27 dB total attenuation, 10W, and works well up to 6GHz. The left end is marked "input". 

On Fri, May 7, 2021 at 01:01 PM, John Quarmby wrote:

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com


QRP PA devices for 10 GHz

Greg - ZL3IX
 

We've recently seen a couple of posts on this group about higher power (and expensive) PA devices, but what are guys using for the lower powers, maybe 0.5 - 2W? Are there devices around for a more reasonable price? I'm making fair progress with my home brew transverter for 10 GHz, and the next stage will be to produce a little power on the band. ideas?


Re: 10 GHz 35W GaN PA devices arrived

David Law
 

I'll bring the dish, you bring the amp and we can listen to ourselves off the moon!


Re: Microwave dish size and shape versus frequency question

KENT BRITAIN
 

Interesting way to think about it,   But the focal points for the 2.4 GHz and 10 GHz waves are slightly different
since 2.4 GHz waves cannot become an infinitesimal point.     Of course 10 GHz wave cannot either.
And 2.4 GHz feeds and 10 GHz feeds will have different phase centers.   

In the practical world the points are pretty close and just make your feed support adjustable and move it
in and out a bit for best signal levels.   I have tested hundreds of dishes on the antenna range and the feed 
usually ends up a bit closer to the dish than the calculated focal point. 

Frequency limits on the size of the dish.

The dish needs to be a least 5 wavelengths across to bring the waves to a focus.

                 For 23 cm this would be about a 1 Meter dish.    10 wavelengths is preferred.

Upper frequency is determined by the surface accuracy of the dish surface.

                 Most commercial dishes are good to 24+ GHz

The offset dish can be more difficult to work with since the feed point is not as obvious and
pointing can be more difficult.  But it gets the feed structure out of the beam.  

Good luck with your project, Kent



On Friday, May 7, 2021, 08:28:18 AM CDT, Chris Wilson <chris@...> wrote:




  07/05/2021 14:20

Absolute newbie question coming...

I saw a big microwave dish advertised on Ebay and then by coincidence saw this advert mentioned on a UK Satellites forum. I am getting started in amateur radio satellite communications, initially via a 1.8 meter PF dish and the QO-100 satellite using SSB and hopefully later, ATV signals.

The up link is on 2.4 GHz and someone extolling the magnificence of the Ebay dish was shot down by someone saying it may well be no use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.

This surprised me, I naively thought a dish was a dish, with prime or offset focus, but now thinking deeper I recall seeing very small, but seemingly deep versus diameter 10GHz dishes on tripods.

So may I ask, how is the size / shape of a microwave dish related to its intended frequency usage please? Thanks.

This is the link to the dish in question:


--
      Best Regards,
                  Chris Wilson.
mailto: chris@...







Re: Microwave dish size and shape versus frequency question

Neil Smith G4DBN
 

Hi Chris, so long as a dish is large enough relative to a wavelength to avoid diffraction loss at the frequency chosen, and the surface irregularities are small enough relative to a wavelength to prevent loss from phase errors, *and you can illuminate it fully without much spillover*, then the depth of the dish does not matter much.

Usual vague rule of thumb is that the dish diameter needs to be at least 10 times the wavelength and surface errors need to be about a tenth of the wavelength across the entire surface.  As a dish gets deeper, it gets harder to illuminate the surface unless you use a subreflector, so most PF dishes have a focal length about 0.3 to 0.5 of their diameter. Offset dishes tend to be shallower, perhaps 0.5 to 0.7 f/d ratio.

Subreflectors need to be a minimum of 8-10 wavelengths, so a very deep dish 2m wide at 13cm would need a subreflector over a metre in diameter, and that would block the dish very seriously, so deep dishes under f/d 0.3 are generally only used where the diameter is 40 or more times the wavelength.  With an f/d 0.25 dish, the focus is in the same plane as the edges of the dish, so the feed has to be able to illuminate the edge at 90 degrees to the axis, which is challenging.  Worse, you usually set the illumination so it is about 10-12 dB down at the edge of the dish to get best efficiency with least spillover, but in an f/d 0.25 dish, the edge is twice as far from the focus as the centre, to there is an additional 6dB of taper added (space attenuation) and the feed needs to be only 4-6 dB down at 90 degrees. 

Those 1.8 dishes are probably OK at C-band, and might even work at 12 GHz.  Definitely OK for 2.4 but very very sharp and potentially too gainy at 10 GHz if the surface is accurate.  If it isn't very accurate, the beam will be less sharp and more useable.

For narrowband use on QO100, 800 mW to a 95 cm dish gets me to the reference beacon level, so you would probably only need 125 mW to get to the reference level on narrowband to the 1.8m dish. For TV use, obviously you need to be running more power, but that giant dish will mean you can under-run a big PA to get minimum spectral regrowth and a super clean signal.

I reckon a 1.0 to 1.2m offset dish is about the sweet spot for QO100 unless you have loads of space and something very solid to bolt a 1.8m pf dish down to.

Neil G4DBN


On 07/05/2021 14:27, Chris Wilson wrote:

  07/05/2021 14:20

Absolute newbie question coming...

I saw a big microwave dish advertised on Ebay and then by coincidence saw this advert mentioned on a UK Satellites forum. I am getting started in amateur radio satellite communications, initially via a 1.8 meter PF dish and the QO-100 satellite using SSB and hopefully later, ATV signals.

The up link is on 2.4 GHz and someone extolling the magnificence of the Ebay dish was shot down by someone saying it may well be no use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.

This surprised me, I naively thought a dish was a dish, with prime or offset focus, but now thinking deeper I recall seeing very small, but seemingly deep versus diameter 10GHz dishes on tripods.

So may I ask, how is the size / shape of a microwave dish related to its intended frequency usage please? Thanks.

This is the link to the dish in question:

https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

-- 
Neil
http://g4dbn.uk


Re: A Proud Owner CG

Algenon M0JIO
 

Thanks for all your replies- very helpful. I like Ben’s set up in a box, so I shall build one of those and use LMR400 from the Dxshop. 

I’ll be back with an update when I get it working. 

73
Alan
M0JIO

On Fri, 7 May 2021, at 07:54, Dave G6HEF wrote:


I second what Nick says re:LMR400. Much more robust than other foil type coax out there that I’ve seen as the foil is bonded to the dielectric helping stop creases that go on to cause fractures.



I look forward to catching you on 23!

Dave
G6HEF



Regards,

Alan. 


Microwave dish size and shape versus frequency question

Chris Wilson
 

07/05/2021 14:20

Absolute newbie question coming...

I saw a big microwave dish advertised on Ebay and then by coincidence saw this advert mentioned on a UK Satellites forum. I am getting started in amateur radio satellite communications, initially via a 1.8 meter PF dish and the QO-100 satellite using SSB and hopefully later, ATV signals.

The up link is on 2.4 GHz and someone extolling the magnificence of the Ebay dish was shot down by someone saying it may well be no use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.

This surprised me, I naively thought a dish was a dish, with prime or offset focus, but now thinking deeper I recall seeing very small, but seemingly deep versus diameter 10GHz dishes on tripods.

So may I ask, how is the size / shape of a microwave dish related to its intended frequency usage please? Thanks.

This is the link to the dish in question:

https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

--
Best Regards,
Chris Wilson.
mailto: chris@chriswilson.tv


Re: 10 GHz 35W GaN PA devices arrived

Chris G0WUS
 

Roasting chestnuts pete lol





Sent from my Galaxy


-------- Original message --------
From: "G1DFL via groups.io" <peterdwberkshire@...>
Date: 07/05/2021 1:08 pm (GMT+00:00)
To: UKMicrowaves@groups.io, Neil Smith G4DBN <neil@...>
Subject: Re: [UKMicrowaves] 10 GHz 35W GaN PA devices arrived

With those little beauties we might hear you in IO91 on 3cm Neil!! ;)

....You could burn a whole through your garden forest!!

Regards..Pete
G1DFL




On Fri, 7 May 2021 at 13:05, Neil Smith G4DBN
<neil@...> wrote:
In its defence, it is a very very fast fuse....

On 07/05/2021 12:56, Denis Stanton G0OLX wrote:
> Neil
> £25 for my 25 Watt TWT doesn’t seem to bad compared to the QRK for a
> nice Fuse
> Denis
> G0OLX
>
>
>> On 7 May 2021, at 12:51, Neil Smith G4DBN <neil@...> wrote:
>>
>> 
>>
>> Afte completing the EAR export authorisation paperwork and being £840
>> poorer, I am now the nervous owner of a pair of VERY fast, horribly
>> expensive fuses.
>>
>> Or, more accurately, GaN PA devices capable of about 42 watts out on
>> 3cm (saturated).
>>
>> Watch this space for updates and pictures of the smoking wreckage
>> once I get the things under test.
>>







Re: 10 GHz 35W GaN PA devices arrived

G1DFL
 

With those little beauties we might hear you in IO91 on 3cm Neil!! ;)

....You could burn a whole through your garden forest!!

Regards..Pete
G1DFL




On Fri, 7 May 2021 at 13:05, Neil Smith G4DBN
<neil@...> wrote:
In its defence, it is a very very fast fuse....

On 07/05/2021 12:56, Denis Stanton G0OLX wrote:
> Neil
> £25 for my 25 Watt TWT doesn’t seem to bad compared to the QRK for a
> nice Fuse
> Denis
> G0OLX
>
>
>> On 7 May 2021, at 12:51, Neil Smith G4DBN <neil@...> wrote:
>>
>> 
>>
>> Afte completing the EAR export authorisation paperwork and being £840
>> poorer, I am now the nervous owner of a pair of VERY fast, horribly
>> expensive fuses.
>>
>> Or, more accurately, GaN PA devices capable of about 42 watts out on
>> 3cm (saturated).
>>
>> Watch this space for updates and pictures of the smoking wreckage
>> once I get the things under test.
>>







Re: Narda attenuator

Andy G4JNT
 

If you make the first such section a 6dB attenuator, the first shunt and series elements dissipate equal power.  Exactly one-third of the input power in each.
That is the case for PI or T topology.



On Fri, 7 May 2021 at 13:01, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> wrote:

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com


Re: 10 GHz 35W GaN PA devices arrived

Neil Smith G4DBN
 

In its defence, it is a very very fast fuse....

On 07/05/2021 12:56, Denis Stanton G0OLX wrote:
Neil
£25 for my 25 Watt TWT doesn’t seem to bad compared to the QRK for a nice Fuse
Denis
G0OLX


On 7 May 2021, at 12:51, Neil Smith G4DBN <neil@g4dbn.uk> wrote:



Afte completing the EAR export authorisation paperwork and being £840 poorer, I am now the nervous owner of a pair of VERY fast, horribly expensive fuses.

Or, more accurately, GaN PA devices capable of about 42 watts out on 3cm (saturated).

Watch this space for updates and pictures of the smoking wreckage once I get the things under test.


Re: Narda attenuator

John Quarmby
 

A distributed attenuator of the type suggested by Claudio would certainly make the thermal design simpler and could be realised using thick film resistors on a BeO substrate. You could make a bidirectional version with graded sections at each end.

I had one of those nice 150W Narda attenuators but managed to blow it up, I do remember it being marked as containing BeO.

73

John G3XDY

On 07/05/2021 10:09, i2NDT via groups.io wrote:

good to know Andy!

I naively thought that high power uni-directional attenuators were a combination of several attenuators in series, such as a 3dB at the input followed by a 27dB, to distribute the thermal load on several devices.

Claudio

Virus-free. www.avast.com

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