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Airspy R2 LDO blown


Terry Gaff
 

Hi all,
Has anybody ever had the bias-T LDO device (LP5907MFX-4.5/NOPB) in an Airspy R2 meet it's maker and replace it ? My own one has blown somehow and I need to replace it. I can do this myself but wondering of any recommendations of where to get a couple in europe without costing an arm and a leg... otherwise it's the peoples republic and up to an 8 week wait.
Many thanks.
Terry


Laurie
 

On 11/05/2018 20:58, Terry Gaff wrote:
Has anybody ever had the bias-T LDO device (LP5907MFX-4.5/NOPB) in an Airspy R2 meet it's maker and replace it ? My own one has blown somehow and I need to replace it. I can do this myself but wondering of any recommendations of where to get a couple in europe without costing an arm and a leg...
Digikey?

https://www.digikey.co.uk/product-detail/en/texas-instruments/LP5907MFX-4.5-NOPB/296-39064-1-ND/5143093

Laurie
--


jdow
 

On 20180512 02:12, Laurie wrote:
On 11/05/2018 20:58, Terry Gaff wrote:
Has anybody ever had the bias-T LDO device (LP5907MFX-4.5/NOPB) in an Airspy R2 meet it's maker and replace it ? My own one has blown somehow and I need to replace it. I can do this myself but wondering of any recommendations of where to get a couple in europe without costing an arm and a leg...
Digikey?
https://www.digikey.co.uk/product-detail/en/texas-instruments/LP5907MFX-4.5-NOPB/296-39064-1-ND/5143093
Minimum order?
{^_^}


Laurie
 

On 12/05/2018 10:30, jdow wrote:
On 20180512 02:12, Laurie wrote:
Digikey?

https://www.digikey.co.uk/product-detail/en/texas-instruments/LP5907MFX-4.5-NOPB/296-39064-1-ND/5143093
Minimum order?
Minimum order is 1 but they do charge £12 shipping for orders under £50.

Laurie

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Martin Smith
 

There is a PPTC for the Bias-T ( https://en.wikipedia.org/wiki/Resettable_fuse ) on the Airspy NOS R0 and Airspy NOS R2. I think it is marked as FB2 on the PCB, but I could be wrong (see bottom left of pin assignment images http://www.pe0sat.vgnet.nl/sdr/receivers/airspy/ )

The PPTC will protect against short duration accidental current overload (or shorting out) of the Bias-T. But it is still best to avoid tripping the PPTC. According to wikipedia it can take minutes/hours/days/weeks/months to recover from overloading a PPTC long enough. I'd be inclined to unplug it for a week and see if the the PPTC regenerates.


Andrew Sutcliffe
 

I'd measure the pptc first and if it is open then pop the unit in a sealed airtight bag and put in the freezer for a couple of days - then remove it and allow 24 hours for it to return naturally to room temp and try again.

S>

At 10:55 AM 12-05-18, you wrote:
On 12/05/2018 10:30, jdow wrote:
On 20180512 02:12, Laurie wrote:
Digikey?

https://www.digikey.co.uk/product-detail/en/texas-instruments/LP5907MFX-4.5-NOPB/296-39064-1-ND/5143093
Minimum order?
Minimum order is 1 but they do charge £12 shipping for orders under £50.

Laurie

--



Terry Gaff
 

Guys,
Many thanks for your information and links etc.
I checked the PPTC device and there is continuity across it, so that's a good thing. However, take a look at the attached pic, I think it leaves one in no doubt as to it's health. So, I guess I'll order a couple of these...somewhere :).
Many thanks for now.
Terry


Support@...
 

You're probably aware, but just incase...

Farnell list them for 38p each with a MOQ of 5 so £1.90+P&P+VAT (£1.90 + £3.95 + £1.17 = £7.02), but they're on back order till mid June. Quicker than 8 weeks though.
http://uk.farnell.com/texas-instruments/lp5907mfx-4-5-nopb/ldo-fixed-4-5v-0-25a-sot-23-5/dp/2492305?ost=LP5907MFX-4.5%2FNOPB&ddkey=http%3Aen-GB%2FElement14_United_Kingdom%2Fsearch


Terry Gaff
 

That overall cost sounds reasonable, I think I'll go for those from Farnell as I'm not in too much of a hurry... (I have two Airspy R2s).
Many thanks indeed for the link, much appreciated.
Terry