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Old 10-Sep-2013, 12:51 AM   #1
Pete Higgins
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Winegard LNA-200 BoostXT Outdoor Ultra Low Noise Preamplifier

Winegard advertises their LNA-200 mast mounted preamplifier with some pretty impressive specifications : VHF (Low) Gain: 20 dB, VHF (High) Gain: 15 dB
Power Out (P1db): +15 dBm
Output IP3: +25 dBm
VHF Noise Figure: 3.0 dB

UHF Gain 18 dB
Power Out (P1db): +18.4 dBm
Output IP3: +35.5 dBm
UHF Noise Figure 1.0 dB

They also list its “Maximum Total Input (microvolts)” as “2,024,789”.


Since I have one local FM station on 99.9 MHz @ -13.4 dBm and a local TV station on RF channel 26 (24.1- .4) @ -15.6 dBm that overloads both my Winegard AP-2870 and HDP-269 models I had hoped this new amplifier would live up to its promise –so I bought one. Unfortunately, it didn’t!

I received my new Winegard LNA-200 late Wednesday afternoon (4 Sep 2013). Thursday morning I started to test it. I have a Solid Signal HDB-8X fix mounted on a pushup mast pointed towards Los Angeles. I was using just the UHF portion of an RCA TVPRAMP-1R (#2) configured for separate UHF/VHF inputs and the FM trap selected with the HDB-8X. I have a dedicated RG-6 run from the HDB-8X to a coax switch in my garage. Since it required the least amount of climbing to get at and only took swapping two cables I substituted the new Winegard LNA-200 for the HDB-8X’s RCA TVPRAMP-1R.

Before I took the RCA out of line I ran through the LA channels to verify everything was working. Then I swapped out the power supplies, went up on the roof and swapped out the amps, returned to the garage to power the Winegard and came in to check reception.

The new Winegard appeared to be working except KTLA RF channel 31 (5.1-.3) was missing. Since Winegard advertises this amp to withstand a “Maximum Total Input (microvolts)” of 2,024,789 µV which in a 75 ohm system, I believe, should be a signal level of about +17.38 dBm I wasn’t expecting this. Interesting! Both because the HDB8X shouldn’t have much response to the FM signal and the one strong TV station is almost 33 dBm below the advertised “Maximum Total Input (microvolts)”.

Above the HDB8X, I have a Radio Shack 15-1220 rotor turning a Channel Master CM-4228 and a Winegard YA-1713 High VHF antenna. I usually leave those antennas pointed towards the San Diego stations. I was also using an RCA TVPRAMP-1R (#2) configured for separate UHF/VHF inputs and the FM trap selected with that array. I decided to try the Winegard LNA-200 with the VHF/UHF array. I reconnected the HDB8X to its original RCA (#3). Since the LNA-200 only has one input I disconnected the separate VHF & UHF cables from the array RCA amp and connected them through a UVSJ. The output of the UVSJ went to the LNA-200 input and the LNA-200 output went through a separate RG-6 cable to the power inserter in the garage. I now had the HDB-8X/RCA’s power inserter and the CM-4228/YA-1713/LNA-200’s power inserter feeding opposite sides of the coax switch. The first difference I noted, when I substituted the UVSJ and the LNA-200 for the RCA, channel 26 was coming in with a very watchable SNR of ~18.5. With the RCA amp and the array pointed towards San Diego I don’t receive my local RF channel 26 at all. I am guessing this is due to the signal ingress issue ADTech reported on.

I rotated the array towards LA. As expected, RF channel 26’s SNR jumped to 30. That’s the highest my tuner cards register. When I tried RF channel 31 it was still gone! I went out in the garage and switched to the HDB8X/RCA and channel 31 popped back in with an SNR of 24.7.

Removed from its plastic case, the circuit board measures 3 15\32” X 1 5/8”. The 1 5/8” grows to 2 5/16” if you measure to the ends of the ‘F’ connectors.

Front


Back


It appears to have three active amplifiers (Q1-Q3)
Closeup


In all fairness, I’m reporting on one LNA-200 sample, tested at my unique location. I’m sure it is a good product that would work well for many people. It didn’t show the pronounced overload I experienced with my AP-2870 and to a lesser degree my HDP-269 but in spite of its advertised overload specifications it none the less appeared to be overloading. Additionally, unlike the RCA’s that at least have a metal plate shielding their circuitry, the LNA-200 is completely housed in a plastic case. I’m pretty sure it’s this lack of shielding that allowed local signal ingress when the antenna was pointed 125 deg. away from the received signal.

On the channels that both amplifiers receive clearly, it looked like the LNA-200 might have a few tenths of a dB SNR advantage over the RCA’s, but keep in mind I was comparing the $23.00 RCA’s, connected to a lower fixed mounted antenna, to the CM-4228/LNA-200 mounted 10’ higher, that I can peak for best SNR with a rotor.


When ADTech tested his sample he found: “On the LNA200, I measured an average of 4.7 dB NF on low-V, 5.6 dB on high-V, and 2.8 dB on UHF as computed by the NF meter software. Major spikes from ingress were evident, some as much as 8 dB.” His test results seem to correlate with the performance I experienced.
Attached Images
File Type: jpg LNA-200 Input Power.JPG (36.3 KB, 6447 views)
File Type: jpg LNA-200 Ckt Board Front 2.JPG (250.2 KB, 7177 views)
File Type: jpg LNA-200 Ckt Board Closeup.JPG (26.7 KB, 6495 views)
File Type: jpg LNA-200 Ckt Board Back 2.JPG (123.9 KB, 6345 views)

Last edited by Pete Higgins; 10-Sep-2013 at 12:55 AM.
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Old 10-Sep-2013, 2:06 AM   #2
tripelo
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Pete, thanks for the report and the images.

About the images.

Can you try to read any numbers or letters on:

Q1, Q2, Q3
D1 & D2

The numbers and letters on each device will likely be 3 characters

(such as 3F4, or something similar)

About the TZJ (cannot read for sure? it's above Q2),

Does it look like a diode?

And, TZ2 or T22 near the input connector, does it look like a diode? could be a transient protector?

Q4 and Q5, fairly sure they are regulators. Are they leaded components, like TO-92, TO-93 cases? If so, do you see any nomeclature?

A small flashlight and magnifying glass can be very helpful, also try lighting from different angles.

Thanks
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Old 11-Sep-2013, 2:22 AM   #3
Pete Higgins
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Re: Lna-200

tripelo,

I have a large 4 ľ” articulating magnifying glass surrounded by a florescent light. Even with that and a 2 7/8” hand held magnifying glass some of the writing is too small for me to read. A component in this amp marked the same as the components in my AP-2780 & HDP-269 marked with a centered red dot and Brown & Green dots at one end that I couldn’t identify are labeled L15 on this circuit board.

Q1, has N4 written above W36. Q2, the only thing I could read was 4F. Q3 looked like it might say 3L but I couldn’t be sure. My wife’s younger eyes saw the same thing.

D1 is marked A6.
D2 is marked 5D 3.

TZ1-3 are small components about the size of a fly speck! It doesn’t look like they are big enough to write on. TZ1 is by the power in/TV out connector and showed a front-to-back like a diode.
TZ2 is by the antenna connector and TZ3 is by Q2. With my eyes I couldn’t see to get a probe in to take readings on these two.

The pads marked Q4 and Q5 are covered over by solder –no components installed. In addition, they are surrounded by a number of unpopulated pads. Whatever was intended to populate these areas would have been surface mount because there are no thru-holes.
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Old 11-Sep-2013, 3:02 AM   #4
tripelo
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Thanks Pete,

Your work is helpful.

Will post some detail in a day or so.
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Old 11-Sep-2013, 12:55 PM   #5
tripelo
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Winegard LNA-200 Components

Hi Pete,

The following is some guesswork based on your images and information.

It appears that the LNA-200 has two active amplifier devices.

The UHF portion is amplified by Q2, an ATF-54143. The ATF-54143 is an industry-standard pHEMT transistor. As a broadband amplifier, at TV frequencies it can readily achieve noise figures below 1 dB. It and most other pHEMT devices are very susceptible to transients Voltage (ESD or atmospheric discharge). It, or a very similar device, was used in the Kitz KT-200, and another low noise pHEMT-based TV preamplifier.

Q3 is a part of the bias regulator (current mirror) for the ATF-54143.

The VHF portion is amplified by Q1, probably an NPN transistor.

The TZx are Tranzorbs. Fairly sure TranZorb is a trademark name of the company that originated them. They are transient voltage suppression diodes. Tranzorbs are similar to Zener diodes, with some special characteristics for particular applications (probably low capacitance and such). These help protect the transistors (especially the ATF-54143).

D1 and D2 are signal diodes, one or both, could be involved in protecting the transistor Q1 from transients.

The component L15 is an inductor, Coilcraft makes similar, the dots indicate the amount of inductance. It is probably part of the power supply circuitry.

Some of the spiral PCB inductors are associated with the input and output diplexers. Like UVSJ, the diplexers separate VHF and UHF for amplification then recombine at output. Also, some spiral inductors are associated with the FM Trap.

Relating to the noise figure and signal handling capabilities:

- The spiral inductors used in the FM trap and the diplexers have lower Q than open-air wound inductors. Thus, they have more signal loss.
- The Tranzorbs and the diodes used for input protection also introduce losses.

Losses at the input contribute directly to the noise figure of the unit.

- The nonlinearities of the diodes and Tranzorbs may generate intermodulation products from very strong signals.

As evident in this preamplifier:

Preamplifier design often involves tradeoffs between low noise figure, ESD susceptibility, and signal handling capability.
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Old 12-Sep-2013, 12:54 AM   #6
Pete Higgins
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Re: Lna-200

tripelo,

Thanks for your input.

I downloaded the data sheet for Q2, the Avago ATF-54143 and sure enough their data sheet says the 4F I read is the device code for that part. The date code character must have been too small for either my wife or I to read. You probably are also right about Q3’s function as well since their data sheet shows a schematic for an example active biasing ckt. and says “Active biasing provides a means of keeping the quiescent bias point constant over temperature and constant over lot to lot variations in device dc performance.”, both of which would be essential in a production design intended for outdoor use.

I thought at first Winegard might be advertising the UHF amplifying device NF instead of the overall amplifiers NF but the ATF-54143 data sheet lists a 0.5 dB overall noise figure for the device and depending on drain-to-source voltage and current less than half that across the UHF TV band, so that’s not it. Also, in his less than pristine environment, ADTech found a 2.8 dB average NF on UHF for the LNA-200 which is slightly worse than the 2.6 dB he found for the RCA TVPRAMP1R he tested. Do you think his environment could be contributing a noise floor or NF threshold?

Avago’s data sheet also says that “The device can handle +20 dBm RF Input Power provided IGS is limited to 2 mA”. I’m not quite sure how to interpolate that number in terms of Winegards advertised “Maximum Total Input (microvolts)” of “2,024,789” which in a 75 ohm system, I calculated to be a signal level of about +17.38 dBm unless they are being a little conservative with this rating (~˝ the power ?). And, given both of those numbers, I don’t understand why I was seeing what appeared to be overload. I assumed that overload was creating spurious responses that raised the noise floor above my channel 31 (5.1-.3) MDS signal level. That was definitely a characteristic of the LNA-200 when hooked to two different antennas because in both cases when I replaced it with one of the RCA’s I got the channel back. I don’t think it was the gain differential because when I was using the +15 dB PCT MA2-M’s I always got channel 31.

About the only thing I think I do understand is getting my local TV station with the antenna pointed to San Diego. The RCA’s are shielded and the Winegards are not.
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Old 12-Sep-2013, 2:11 AM   #7
tripelo
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Quote:
Originally Posted by Pete Higgins View Post
...Do you think his environment could be contributing a noise floor or NF threshold?
Don't know.

Years ago, I measured noise figure of VHF & microwave prototypes for military use. The prototypes would be similar to an unshielded TV preamp.

Here in Dallas, the ambient noise floor was high enough that often the results were contaminated. The problem was cured after a solid copper lined test room was built especially for this (called a screen room). The room had special RF tight ventilation.

Undoubtedly, the VHF spectrum is busier now, than then.

I can see it now, on the Sencore 1456 spectrum analyzer. I have to make a metal case for anything that I hope to take S/N measurements, here.

-------------------------------

However, there appears to be enough lossy components in front of both the VHF transistor and the ATF-54143 to cause the noise figures of the devices to substantially degraded.

Keep in mind that a preamp like the original CM-7777 used transistors that could have a raw device noise figure slightly above 1 dB, but the preamp specification is 2.8 dB (VHF) and 2 dB (UHF). By some measures the CM-7777 has, or had a tough time of meeting specifications. And, Channel Master used low loss coils.

Quote:
The device can handle +20 dBm RF Input Power provided IGS is limited to 2 mA”. I’m not quite sure how to interpolate that number in terms of Winegards advertised “Maximum Total Input (microvolts)” of “2,024,789” ..
That's interesting. without doing any looking at the data sheet.

That maximum total input appears to be the instantaneous Volts the device can sustain without failing. It seems much more than the device can handle in a linear fashion (without IMD and harmonic distortion).

If it linearly amplified 2 Volts, the output could be 20 Volts. Not likely with a 3+ Volt supply.

Quote:
...which in a 75 ohm system, I calculated to be a signal level of about +17.38 dBm unless they are being a little conservative with this rating (~˝ the power ?).
Winegard's Transzorbs and diodes are probably set up to limit input Voltage for some margin of safety.

Quote:
And, given both of those numbers, I don’t understand why I was seeing what appeared to be overload.
The naked ATF-54143 is superior in terms of linearity (signal handling capability), than the NPN transistors that the RCA uses.

It takes much more stringent ESD protection to keep a 54143 alive than the NPN devices.

It could be that the transient protection around the 54143 is introducing some distortion from the strong signals.

When signal strength is high, diodes and Tranzorbs are good IMD & harmonic generators.

.

Last edited by tripelo; 12-Sep-2013 at 1:53 PM. Reason: typo
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Old 12-Sep-2013, 4:53 AM   #8
Pete Higgins
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tripelo,

When I was doing surveillance work in the mid to late 80’s the company I was working for had a combination screen room/SCIF built for my testing. That’s when I had my own HP 8920’s and 8921’s with spectrum analyzer and tracking generator capabilities. I also had network analyzers, signal & function generators and scopes. Old by today’s standards but I wish I still had access to that equipment. The VP of engineering often encouraged me to bring stuff home for my own projects. Now, I have a 60 MHz scope with a digital readout, a couple of 1 GHz frequency counters, a 40 MHz sweep/function generator and various bench supplies. I do still have a couple of zero centering VTVM’s in case I ever need to align an FM discriminator! I guess my prize piece of test equipment is a late 50’s RCA WO91-A Oscilloscope that still works perfectly. I got it almost new but not working when I was 14-15 years old and had it fixed within a couple days. I used it for years with my B&K 415 sweep/marker generator for aligning TV & FM radio IF strips. Unfortunately, I don’t have anything for looking at the UHF TV spectrum or evaluating ATSC signal quality other than the software SNR meters that work with my Hauppauge HVR-1800 tuner cards.
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Old 12-Sep-2013, 2:01 PM   #9
tripelo
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Quote:
Originally Posted by Pete Higgins View Post
When I was doing surveillance work in the mid to late 80’s the company...
Interesting. You obviously have familiarity with test equipment and testing methods.

Quote:
...Old by today’s standards but I wish I still had access to that equipment.
Takes a lot of space, but would guess some of that equipment is pretty useful.

Quote:
...looking at the UHF TV spectrum or evaluating ATSC signal quality other than the software SNR meters that work with my Hauppauge HVR-1800 tuner cards.
Some of the tuners have very good signal level and quality indications. Often sufficient for most home DTV work.
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