Airspy R2 Front End Overload

RDowson

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I’m having major problems with my Uniden scanner and front end overload due to a very powerful VOLMET broadcast from a nearby mast.
How does the Airspy R2 cope with this? Am I likely to see an improvement over the Uniden scanner?

I’m desperately looking for a solution and I’m hoping switching to SDR (Airspy R2) will be the answer.

Thanks!
 

BTJustice

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What frequency/frequencies is the VOLMET transmitting on? You may need a filter to block it out. The Airspy R2 (and Mini) work well in overloading situations, but they are not perfect. It just depends how powerful this VOLMET is.
 

Reconrider

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Is it in the base band as what you're trying to listen to? If not, get a tuned antenna for the band you wanna hear.
 

RDowson

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What frequency/frequencies is the VOLMET transmitting on? You may need a filter to block it out. The Airspy R2 (and Mini) work well in overloading situations, but they are not perfect. It just depends how powerful this VOLMET is.
It’s 125.725 (Scottish VOLMET). There’s quite a few nearby frequencies that it blasts through when using the Uniden.
 

dlwtrunked

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I’m having major problems with my Uniden scanner and front end overload due to a very powerful VOLMET broadcast from a nearby mast.
How does the Airspy R2 cope with this? Am I likely to see an improvement over the Uniden scanner?

I’m desperately looking for a solution and I’m hoping switching to SDR (Airspy R2) will be the answer.

Thanks!
One of the biggest advantages with an Airspy is that you can adjust the gain to help alleviate the problem. Besides that, it is a good receiver.
 

RDowson

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One of the biggest advantages with an Airspy is that you can adjust the gain to help alleviate the problem. Besides that, it is a good receiver.
Will adjusting the gain not reduce the range I can pick up signals from though?
Would switching to my small indoor antenna not to the same thing?
 

dlwtrunked

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Yes and pretty much yes.
But many people adjust the gain too high (with no benefit but adding problems). (The real desire is high signal-to-noise rather than high gain.)
switching to an indoor antenna does not do the same thing--it usually is lower (and height matters a whole lot and you likely want that for your signal) and also you do not have the flexibility in adjusting the gain that way.
 

Ubbe

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It’s 125.725 (Scottish VOLMET). There’s quite a few nearby frequencies that it blasts through when using the Uniden.
Isn't VOLMET for shortwave, and can be powerful, and it's called ATIS for VHF? Atis are just a 10W transmitter. You shouldn't have any problem using the older style Uniden scanners up to 436/536. It's another matter with SDS100/200 as they receive adjacent frequencies very easily due to the internal intermodulation in its receiver. Try different filter settings and IFX, or buy a second hand BCT15X or UBC125AT.

It's always a good idea to have a £10 variable 0-20dB attenuator at hand to put in line with the antenna and adjust for best signal/noise relation. It will be pretty much the same as adjusting the gain in SDR receivers.

/Ubbe
 

boatbod

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If the transmitter is close by I think you'll end up needing a filter. SDR receivers are wideband and subject to intermod so I suspect performance will be as bad or worse than the SDS.
 

dlwtrunked

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Hmm. Turn the gain down if possible. That might help a little bit
He is using a scanner where he is limited in doing that which is why I recommended
If the transmitter is close by I think you'll end up needing a filter. SDR receivers are wideband and subject to intermod so I suspect performance will be as bad or worse than the SDS.
Your suspicion is wrong regarding higher end SDR's which do incorporate filtering.
 

boatbod

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Your suspicion is wrong regarding higher end SDR's which do incorporate filtering.
If you say so. I can only go by my experience with (cheap) Noolec RTLs and (less cheap) Airspy Minis, both of which are quite happy to intermod given half a chance. Perhaps the Airspy R2 is significantly better than the Mini?
 

dlwtrunked

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If you say so. I can only go by my experience with (cheap) Noolec RTLs and (less cheap) Airspy Minis, both of which are quite happy to intermod given half a chance. Perhaps the Airspy R2 is significantly better than the Mini?
If you turn up the gain higher than it should be, any receiver will have intermod. It is just easier to see it with an SDR.
I have 6 Airspy ( 2 R1, 2R2, and 2 Mini). I can adjust the gain so there is not more than a problem than the SDS200 that I have. Infact, if I look at the IF of my ICOM R9500 or ICOM R8600, I can see the SDRs are as good as them. (Note the ICOMR8600, a top line receiver is actually SDR based.
 

dlwtrunked

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KA1RBI

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There’s quite a few nearby frequencies that it blasts through when using the Uniden.
It makes a difference what model of Uniden you have. If it's the SDS series (as has been noted here by K2HZ) they are a "disaster on VHF".

Some users in quieter RF areas have no problems with the SDS but the VOLMET station as you've described it is exactly the kind of signal that is going to cause problems in the SDS.

Isn't VOLMET for shortwave, and can be powerful, and it's called ATIS for VHF?
In the US, yes. In UK, not so much. From wikipedia

VOLMET (French origin vol (flight) and météo (weather report)), or meteorological information for aircraft in flight, is a worldwide network of radio stations that broadcast TAF, SIGMET and METAR reports on shortwave frequencies, and in some countries on VHF too.
 
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