Mini-Circuit Low Noise Pre-Amp 10% Off December and Other Useful RX Items

[JamesO]

So I have been playing around with a LOT of different Pre-Amp configurations lately and I have round that the Mini-Circuits ZX60-P103LN+ Low Noise Pre-Amp is a REALLY nice performing LNA/Pre-Amp. 50 MHz - 3 GHz, 13 dB Gain, 0.6 Noise Figure, 40 dBm P3!!!

With the December 10% discount, you are looking at about $75 for this LNA shipped.

Granted this Amp may not have as flat of a gain response as some people might like, the very low Noise Figure clearly makes up for this gain tilt. Please note this Amp is a 5 Volt device so if can easily be powered by a small USB wall adapter or you can do what I did and mount a LM7805 Voltage regulator and a few capacitors directly on the amplifier so I could phantom feed the coax with an adjustable Voltage without worrying about the Amplifier that is located directly at the base of the antenna installed on a FM Broadcast band notch filter.

Mini-Circuits

If you live in a urban/city area you will most likely require a FM Broadcast notch filter. I live with 3.5 miles of two 22 kiloWatt transmitters and 5 miles of a 75 kiloWatt transmitter so I CLEARLY need a FM Broadcast notch filter. You can check on the site FM Fool - Home using your address to see what challenges you have for FM Broadcast in your location. You can also check the sister site TV Fool for TV Broadcast transmitters as well.

The best FM Broadcast band filter I have found is this filter on ebay from a seller iseeabluewhale out of Canada. FM Notch Filter 88-108MHz for SDR; Excellent Rejection 85dB; Bandstop; 9th order | eBay

For you commercial Airband guys, you should check out this Airband Pre-amp with integral band pass filter. A nice and reasonably priced special application Pre-amp for Commercial Airband.l

- Airband Low Noise Amplifier LNA 118-138MHz, preamplifier aviation RTL SDR VHF | eBay

Although these items may show and not listed or sold out, message the seller and I am sure he will make more and list them for purchase.

This guy has some nice stuff, communicate well and the pricing and performance of the items he sells if very good. I also buy some items from an ebay seller novakx5 out of Hungary. Again, all of his items are very good quality, reasonably priced and ship without a problem.

I highly recommend both of these ebay sellers if you are looking for filters, bias-T's and other lower cost amplifiers. These along with the Mini-Circiuts LNA make for some pretty good monitoring!

I still have to relocate my antenna/antennas from inside the attic to outside, but while the antennas are in the attic it allows me quick and easy experimentation of amplifiers and filter without weather or daylight limitations. Much easier to prove the concept and performance before moving on to a more permanent and difficult to reach installation.

What I can say is without the Mini-Circuits LNA and Broadcast band filter, my set up is fairly deaf. I have a long RG-6 run and even trying some of the cheaper LNA's from the ebay users listed above and other LNA's, even some other Mini-Circuits LNA's I was not able to hear an adjacent county 800 MHz trunking system at all. But the Min-Circuits ZX60-P103LN+ has opened up a lot of new listening and now I am committed to get one or more of my antennas moved out of the attic and onto the roof once I have my final filter/LNA configuration sorted out.

I am then going to split the feed into the house into the bedroom and my primary listening room so I can have solid reception on many locations in the house.

I have spent a fair amount of time and money playing with different amplifiers and filters and thought I would pass along what I have found that works well, I clearly think the Pre-amp and filter are WELL worth the $100 investment, I clearly get more that $100 in return regarding signal monitoring.

So if you are inclined and have the money, get yourself some Christmas presents to open up your monitoring world.

 

[JamesO]

Direct link for LNA data sheet - http://www.minicircuits.com/pdfs/ZX60-P103LN+.pdf

 

[Forly192]

Have you tried the airplane-shaped PCB board filter from ebay?

How did the results compare with the Mini-Circuits setup?

 

[Forly192]

JamesO,

Can you tell me where you purchased the Mini Circuits LNA? I can't find a source that sells it.

Thanks.

 

[JamesO]

Have you tried the airplane-shaped PCB board filter from ebay?

How did the results compare with the Mini-Circuits setup?

I have the earlier version of the Airband Pre-amp which was not the airplane shaped Amp. I have not put it to use yet because this Airband Pre-amp is filtered and not a "wideband" Amp. So I need another dedicated coaxial cable to then feed a few radios that will be dedicated Airband units. Something to try and get done in the next few months I guess!

The Mini-Circuits set up has been up and working since before I posted this information and I am monitoring Airband traffic with it. Maybe not as good as a dedicated antenna, narrow band specific Pre-amp, but it I am VERY pleased with the Mini-Ciricuits pre-Amp with the FM broadcast filter on the front end because I am within 4-5 miles of some very powerful FM radio stations.

 

[JamesO]

JamesO,

Can you tell me where you purchased the Mini Circuits LNA? I can't find a source that sells it.

Thanks.

You can often find some used or even new Mini-Circuits LNA's on ebay, but Mini-Circuits sells direct and this is where I purchased my LNA because it was a newer model Amplifier.

I believe I integrated a 5 Volt Voltage regulator and filtering capacitors directly on the Amplifier which allows me to use a 12 Volt supply or even a variable power supply where I can drop the Voltage slightly, which will drop the Amplifier gain for test purposes.

I have a LONG RG-6 cable run and then feed another Amplifier with a higher Noise Figure that then feeds a number of splitters feeding 8 radios. Some applications require attenuation at the input of the 2nd amplifier at to not over drive and compress the Amplifier.

 

[rbm]

I believe I integrated a 5 Volt Voltage regulator and filtering capacitors directly on the Amplifier which allows me to use a 12 Volt supply or even a variable power supply where I can drop the Voltage slightly, which will drop the Amplifier gain for test purposes.

I've done the same with several low noise amplifiers.

I have nine pre-amps at the antennas most use 12V and several use 5v.
The three terminal regulators with capacitors have been working well for a number of years.

That allows me to run just one voltage source to the antennas.

Rich

Mini Circuits with three terminal voltage regulator - Imgur

..

 

[JamesO]

I've done the same with several low noise amplifiers.

I have nine pre-amps at the antennas most use 12V and several use 5v.
The three terminal regulators with capacitors have been working well for a number of years.

That allows me to run just one voltage source to the antennas.

Rich

I have done something like this, however, I think the current LNA I am running has small mounting ears and I actually bolt the heat sink/negative side to one of the mounting ears.

I like the 5 Volt LNA's much better than than the 12-15 Volt Amplifiers as this automatically compensates for Voltage drop in the coax and Bias T configuration that I typically run.

I have had the current configuration operating for almost a year without any problems.

I probably need to get some pictures of my configuration and post them when I get a chance.

9 Pre-Amps and the antennas?? Are these all in one location? If so are you running Band specific Amps and are you running any FM Broadcast filters or any input/band pass filtering?

What model Amplifiers are you typically running?

 

[rbm]

I'm running a number of different make/model pre-amps.
They're all mounted inside PVC housings like this::
https://i.imgur.com/pP29m4d.jpg

For everything 600 MHz and below, I typically use the RF Bay, Inc LNA-580.
I also use the LNA-580 on my X-Wing antenna for SatCom
https://i.imgur.com/apVKDxR.jpg

For 450 MHz and up (including ADSB), I typically use Mini Circuits ZQL-1900MLN Pre-amps

They're all mounted at my home within 5-10' of each other.
I haven't had a need for any bandpass filters.
I use variable attenuators if needed, but I haven't had the need yet.

20 years ago at my previous home, I was most of the way up a mountain and within sight of a number of commercial TV and other broadcast antennas.
There, I would increase the attenuation enough to tame everything down.
Once I did that, everything was stable for years.


Rich

Some of the spare pre-amps:
https://i.imgur.com/940kxvU.jpg

Performance of the Mini Circuits ZQL-1900MLN:
https://i.imgur.com/ShM52QM.jpg

.

 

[JamesO]

Pictures of the set up I am using - https://www.dropbox.com/sh/hmvxvtev71z09z8/AACpt0RSsfk5BI5T2JD0WOfNa?dl=0

I went though 6-8 different Pre-amps/LNA's and 6 different FM broadcast band notch filters before I found a good combination that performed to my expectations and was able to pull in a lot of more distant stations.

 

[R0am3r]

Has anyone tried the low priced LNAs listed on eBay? Some of the LNAs are priced in the $6 - $9 range and offer gains from 20-30dB with a bandwidth that covers 50MHz - 2GHz (others up to 4GHz). Unfortunately, the vendors don't always provide a Noise Figure, so I wonder how good they are.

Another LNA on eBay is the GPIO Labs PGA103+ unit that sells for $29.70. This particular unit has a gain of 20dB with a Noise Figure of 0.5 dB at 400MHz.

Thoughts on any of these LNAs?

 

[prcguy]

Gain and noise figure are two important specs, but for an LNA you also want to know its 1dB compression point (IP1) or its related and calculated IP3 spec. Its better to have the gain in the 15dB range +/- a few dB and a 1dB compression point of 25dBm or more, preferably a lot more if you can afford it.

In many if not most major cities in the US, if you put a 20-30dB gain amp with a 1dB compression point of say 10dBm or less connected to a wide band antenna like a Discone, I will guarantee you will wreak your reception of weak signals due to intermod generated within the amplifier.

Last time I had to prove this to a group of digital bit herders trying to invent an SDR radio I measured an aggregate signal level of -10dBm coming off a Discone antenna we had on the roof. Connect a 30dB gain amp with a compression point of 10dBm and you have a real mess. Even a 15dB gain amp with a 1dB compression point of 25dBm will generate some IMD affecting weak signal reception under the conditions I measured.

There is a reason a high end, high level, low NF amplifier cost a lot of $$. The Chinese can certainly do it for less than we can in the US but for $6 or $9 you will get what you pay for and I wouldn't bother.
prcguy

Has anyone tried the low priced LNAs listed on eBay? Some of the LNAs are priced in the $6 - $9 range and offer gains from 20-30dB with a bandwidth that covers 50MHz - 2GHz (others up to 4GHz). Unfortunately, the vendors don't always provide a Noise Figure, so I wonder how good they are.

Another LNA on eBay is the GPIO Labs PGA103+ unit that sells for $29.70. This particular unit has a gain of 20dB with a Noise Figure of 0.5 dB at 400MHz.

Thoughts on any of these LNAs?

 

[Ubbe]

I haven't gone below $10 but all other LNAs including CATV inline amplifiers have always improved my reception and of course I have to listen to a weak station while adjusting the variable attenuator for best reception. I tested them with big 4-stacked VHF and UHF dipoles 200meters from stockholms most busy site with at least 20 transmitters and 10 of them in constant tx. Here at home I am 30km from the towns centre and not near any site but still need a FM trap filter if I don't attenuate anything.

I bought an $8 combined 4-splitter amplifierer from china and that thing just added noise. Probably had a noise figure of NF 5 or 6. It's marked Seebest 7520FL.

/Ubbe

 

[JamesO]

Has anyone tried the low priced LNAs listed on eBay? Some of the LNAs are priced in the $6 - $9 range and offer gains from 20-30dB with a bandwidth that covers 50MHz - 2GHz (others up to 4GHz). Unfortunately, the vendors don't always provide a Noise Figure, so I wonder how good they are.

Another LNA on eBay is the GPIO Labs PGA103+ unit that sells for $29.70. This particular unit has a gain of 20dB with a Noise Figure of 0.5 dB at 400MHz.

Thoughts on any of these LNAs?

What I do not get is why anyone would even consider spending under $25 for any LNA. There is always talk about expensive antennas and expensive coax then someone is considering a cheap amplifier. DO NOT even waste your time or money.

I put this thread together, and maybe I did not outline what I had gone through to get the end result and why I posted the info I did. I went through over 6 different amplifiers, at lest 3 different Mini-Circuits units, a few of the GPIO Labs amps and a few others I had either laying around that had decent specs and/or that I purchased. The GPIO Labs amp may actually use the same discrete amplifier as the Mini-Circuits LNA, but I found the Mini-Circuits LNA performed a bit better than the GPIO Labs product, not by leaps and bounds, but in my situation where I was dealing with some extremely weak signals, the Mini-Circuits made the difference over the GPIO-Labs LNA and I needed the additional margin.

Here is what I can tell anyone reading this thread, the GIOS Labs LNA you mentioned above is not a bad amplifier, but at the end of the day after a good deal of testing, I determined the Mini-Circuits LNA that I listed in this thread was the best performing LNA that I had tested when it came to small signal recovery. In my specific case, I had to have the 85 dB FM Broadcast Band Notch Filter because I have 3 very high level FM Broadcast tower under 5 miles from my location. I still have a number of GPIO Lab amplifiers on hand that I am not using, but they were very close runner up products to the Mini-Circuits LNA I outlined in this thread.

I am in a very RF challenged environment, I am sure some of the large inner cities may be as bad or worse than my situation, but at the end of the day the Mini-Circuits ZX60-P103LN+ Low Noise Pre-Amp performs very well for me and has hardly any downsides.

One thing with any amplifiers being added into a receive chain is you may need some specific front end filtering and you may actually need to attenuate the signal down before it hits the radio depending on the amplifier gain and the levels leaving the amplifier. There are a lot of variables in the receive chain depending on the coax loss and if you plan on actually spitting the feed to more than one radio.

Ideally you may need a spectrum analyzer to see exactly what is going on, but if you do some initial research and plan accordingly, you can actually end of with very good results.

Anyone considering a LNA purchase, I hightly suggest you PM me so I can get a better understanding on what you are trying to accomplish, where exactly you live so I can offer some guidance for FM band and other strong signals to watch out for and I can probably convince you to not by any sub $25 LNA's because at the end of the day, you will be wasting money. If you procure the right products you will not be sorry with the money you have spent.

There are a lot of variables and it is best to hash out what the station configuration is, the location and what you are tying to solve.

 

[R0am3r]

Thanks to all for the feedback on the LNAs. The purpose of my post was to solicit feedback on LNAs for my specific situation. Since I live in the country here in Upstate NY, my proximity to any high power transmitters (FM, TV, etc.) isn't an issue. My goal is to increase my listening range without introducing too many issues with my existing "locals". My setup is rather simple with a Discone mounted to a mast at 35 feet (~10 meters). The feedline is LMR400 coaxial cable fed directly to my Uniden 536HP. If I can increase range with a simple 20 dB LNA, I have achieved my objective.

Based on what several of you have posted, I am considering the Ultra Linear PGA-103+ LNA that is rated from 10MHz - 2GHz. The gain is > 20 dB with a Noise Figure of 0.5 dB @ 400MHz and the IP3 is +40 dBm @ 2GHz. The price is cheap enough at $34.50 plus shipping. Thoughts? The specs seem ok to me. What am I missing?

 

[JamesO]

R0am3r,

You are not really missing anything. The difference in the LNA's is minor, the GPIO Labs products are good devices. While some of the LNA's use the same discrete component as the Mini-Circuits LNA, I have found the Mini-Circuits performs slightly better overall with fringe signals for my configuration. You could start with the cheaper LNA and see how it works out.


No disrespect to the GPIO Labs folks but you need to be careful when picking something from their ebay site. I think they have had a number of small running changes and some of the items are listed twice or have very small differences. Please provide a link of the exact item you are considering. I think based on the price you mentioned this is a LNA with the USB cable which you may not need.

If you are planning on phantom feeding DC power up the coax, they have another LNA with a built in Bias-T and they also sell Bias-T's for use inside as well of you do not have a SATV type of power inserter. Powering the LNA is something that must be considered.

Please note you really need to install the LNA at the base of the antenna, not at the input to the receiver. You will not have the performance you desire if the LNA is mounted at the input of the receiver. The loss of signal is the coax will not allow the LNA to perform like it should. What happens is many people receive the LNA and then immediately connect it to the input of the radio because it is easy and expect miracles, this will not happen. Then they question the money they spent and the product they purchased. This is only 1 best way to have everything set up and every other configuration will typically not yield good results.

The LNA needs to be mounted at the antenna connection. Additionally do not compare reasonably strong signals and expect a change. You need to identify either fringe signals or systems you cannot even monitor without the LNA and then use these for a benchmark when you install the LNA and compare what happens. For what ever reason, the NOAA broadcast are very weak in my Metro area and I have adjacent 700/800 MHz trunking sites I cannot monitor either inside or unless I have the LNA. I can use the NOAA and adjacent County trunking systems to compare performance with and without the LNA installaed. So make sure you do your homework before you claim the LNA does not work.

While you think that FM radio stations may not be a problem, you really should run your address though FMFool and see what the most powerful stations are at your location. I had 4 stations within my range that were listed at -14 dBm, -14 dBm, -17 dBm and -18 dBm. I had 15 stations that were at or above -24 dBm so I had a big issue to deal with on filtering out FM stations.

Just be aware you may need filtering and you may need to play around a bit with the installation of the parts because things are not always as expected.. Best to keep cabling between the antenna and LNA to a minimum. I was able to use and highly suggest a direct connection to the antenna connection because I am currently operating in the attic. When I move everything outside, I am going to use a PCV set up to shield the LNA. Having the LNA to send the signal down the coax is also a big bonus, this then pretty much negates a lot of the coax loss that may be limiting your monitoring.

 

[Forly192]

I’m curious, how does the scanner handle the widebsnd amplifier?
I understand that by using filters you narrow down what gets amplified, but in theory at least, would such a wide and amp produce some imaging or extraneous noise? Just curious. I mean, again, in theory, I would assume that an amp that’s dedicated to that band would be a better solution and I mean “better” in a theoretical sense.

By the way, thanks for posting your experience and the devices you use. This is a very helpful thread.

 

[Ubbe]

I can add another Hungarian guy selling on ebay https://www.ebay.com/usr/janielectronics

An amplifier produce imagies and noise if they get overloaded, so you'll need to reduce that by using a single band antenna and/or use filters to reduce the risk. It's always some experimenting until you find what works for you. Each setup are unique and probably cannot be transfered directly to another site.

/Ubbe

 

[dlwtrunked]

I can add another Hungarian guy selling on ebay https://www.ebay.com/usr/janielectronics

An amplifier produce imagies and noise if they get overloaded, so you'll need to reduce that by using a single band antenna and/or use filters to reduce the risk. It's always some experimenting until you find what works for you. Each setup are unique and probably cannot be transfered directly to another site.

/Ubbe

Very wise advice that cannot be said not enough times.

I use amplifiers (good expensive ones) and yearly check on what filters and amplifiers are best as over a year, the optimal setup can change with new problem stations coming or old ones disappearing. (As a general rule, FM broadcast filters should always be used (even if you do not think you have a problem--de-sensing does not let you know it is even happening). Next are filters to block VHF powerful pagers if needed. And then filters for other local problems including possible a strong nearby NOAA weather station.) And my receiver these are on is a very good/expensive one as I try to get the best performance possible. An important thing to remember that (the lower the better) noise figure, NF, is important as well as gain. While it is really true that a pre-amp should be at the antenna rather than the receiver, it is also true that sometimes one at the receiver will help if one cannot get to the antenna if the NF of the receiver front end is not "good enough" and also if passive splitters are used. But watch the gain and problems that too much gain may cause. An important word in Ubbe's post is "experimenting"--this is not optional if the better configurations of amplifiers and filters are desired.

 

[JamesO]

As mentioned there are many variables in any receive site and with the signals present at a given location.

I can say overall the set up I am currently using is working quite well for me and I am in a pretty challenging RF environment just outside the Washington, D.C. area which is full of all sorts of RF challenges. While maybe a downtown Metro area may be more challenging in some regards, I have a lot of FM and TV transmitter sites very close to my location.

One thing with any amplifier installation that I have run into over the years is too much gain, over driving stage and putting an amplifier into compression. Too much signal is often a common theme that is overlooked. Proper balancing is a must and sometimes you just have to add attenutation and see what happens.

Often you need to experiment with things like:

Less of an antenna, believe it or not!
Attenuation at the input of the receiver
Input filters - as mentioned an FM Broadcast filter is almost a must IMHO, also go with a high rejection FM Broadcast filter, do not rely on a 30 dB filter even if you think you can get by with it.

With most Pre-amps, IMHO they tend to have TOO MUCH gain, you do not want or need a 30 dB Pre-amp, this is asking for trouble. Better to have a low gain, very low noise figure Pre-amp/LNA and then be able to add you own cascaded amplifier stages and attenuation as needed. This allows for YOU to control the input level to the next amplifier stage. Often far lower input is more desirable than a higher input level.

Having a variable or step attenuator handy for testing is very helpful. This allows for quick changes to the input or output level of an amplifier and will allow for quick comparisons and testing. Once proper balancing can be obtained, fixed level attenuators can be installed as needed. Clearly a spectrum analyzer is helpful, but not everyone has one on hand to use. In the absence of a spectrum analyzer, a cheap SDR dongle can be helpful, but keep in mind most SDR's are very wideband front ends and you may need a 6-10 dB attenuator on the SDR input to help from swamping the SDR and getting erroneous results.

Sure, a more dedicated filtered LNA that is frequency or band specific is best for any installation, but we tend to be more wideband specific users. Even with a wideband LNA like I have mentioned and adding at a minimum a FM Broadcast band filter, you will degrade some adjacent frequencies, but often this is not enough to really matter at the end of the day. It is all user equipment and local specific. Also many of the high end LNA's are not as tolerant to impedance mismatches like we deal with on a typical scanner feed system. Sometimes a 3 dB attenuator installed can held with mismatches an improve the overall performance of an installation. Kind of a poor mans solution.

In some cases the actual radio may make some difference based on the front end design as well. One receive chain set up may work fine with radio A but with radio B, there may be some signals that are still too strong and cause images or intermods within radio B. Again, often additional attenuation will be required.

The problem is most of the scanners internal attenuators are too great, I do not think they are actual attenuators, I think they turn off a gain stage in the radio?? Most scanner attenutators these days are like 20 dB, where as the amount of attenuation for system level balancing will most likely be between 3-10 dB. 6 dB often seems to be a good compromise for levels that are not too far off the mark.

It often seems like when you calculate or plan for a specific system you still need to experiment. I have found over the years that often more attenuation is better when cascading amplifiers. Often too much signal or power is a bad thing. Most of the wideband scanners are pretty sensitive, so unless you have a fair amount of cable loss between the LNA and the receiver, have some attenuators handy and be ready to experiment with them,

While there are a number of 3rd parties on ebay that may offer LNA's with the same Mini-Circuits PGA-103+ discrete LNA but installed in their own circuit board, I have tried and compared a number of these and found the Mini-Circuits LNA will typically out perform these 3rd party circuit board LNA's. Not sure exactly why, but with any LAN the circuit board layout, impedance matching, shield and so forth play crucial rolls in the final overall performance and stability of a good LNA.

When I have time, I need to play around with my system. I need some better Low Band performance for some adjacent State Police systems, the current antenna is not optimized for Low Band. I plan on using a different LNA with a 50 MHz Low Pass filter installed at the base of a lower frequency antenna then using a diplexer and combining the 2 antennas into a single feed line. I think I have most of the parts, I just need to get the time and interest to get this set up.

Again another tweak, adjustment or experiment with my overall system. But this is a specific requirement I have based on my listening needs, location and overall antenna and receive change configuration.