TE Systems....

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N8SAN, Apr 7, 2019.

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  1. WE4E

    WE4E Premium Subscriber QRZ Page

    You'll almost certainly have better success with more antenna. I know you just got that one up. It isn't all about gain, it's also about capture area. Bigger is better.

    Not sure what you're running for feedline either, but even LMR400 is ~1.5db/100ft. Have a look at some LDF4-50 (not superflex). It's half the loss per 100' and the knockoff stuff is $1.15/ft. The connectors are fiddly, but not hard to do. That will do more for you than any preamp, especially one on the ground.

    I'm in the process of taking down a Diamond X200 fed with 9913 and replacing it with an X700 and heliax.
     
  2. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    I have the 350 watt TE amp, it is a fantastic 2 meter amp. 10 watts in gives me 330 out. It's max input is 25 watts and at 25 watts in I get 410 watts out.

    As far as the pre amp it makes no difference on FM using my V8000 but using my IC-251A on weak signal SSB it does help.......A lot .
    I really don't know the quality of the receiver in the IC-251A, I would say for it's age decent, above others of it's generation but not great.
     
  3. N8SAN

    N8SAN Ham Member QRZ Page

    I'm looking at purchasing 2 M2 2M9SSB to run together.
    I was going to use LMR-400 maybe 600 but at 20' max I doubt there will be a difference between the two.
    0.5 db for 100'. But that might be worth something in the end. Ever "ounce" counts.

    Now are you talking about the built in preamp on the TE amp itself? Or a mast mount one?

    How good are the Landwehr ones over say an SSB 2000 superamp? Or ARR? I can't find much feedback on the Landwehr stuff.
     
  4. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    Yea, the built it one, don’t know anything about the Landwehr.

    I certainly would not worry at all on 20’ run.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    With a 20' feedline of even LMR400 @ 144 MHz, a masthead preamp is a waste of time.:p
     
  6. N8SAN

    N8SAN Ham Member QRZ Page

    I knew you'd be here Steve! Don't worry I wasn't undermining your expertise.
    Was wondering if @WA8UEG was referencing the built in preamp.
    And in my travels I've stumbled across the Landwehr name and have never heard of it.
    I have no intention of getting one especially with my Q5 transverter on order. :D
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Steve (UEG) was referring to the preamp in the TE 350W amplifier. It's the same preamp they use in all their amplifiers and it's fine but whether it accomplishes anything or not is entirely dependent on the sensitivity of the receiver after it.

    My quick test, usually, is to just wait until sunrise or sunset so the sun's on the horizon, and point my 2m beam(s) at it. If the noise level obviously jumps up compared with the same receiver connected to a dummy load, no kind of preamp will really help.

    A masthead preamp can help overcome transmission line losses for sure, but with a 20' line that has probably 0.3 dB loss, you'll never notice this improvement and I wouldn't spend a nickel on it. For the cost of a masthead preamp that can bypass a kW (these are in the $400+ range), I'd sink that money into more antennas. Just one more beam (if you start out with one) or two more beams (if you start out with two) and the masts and splitters required for that may not cost more than a good masthead preamp (for high power use) and can add 2.5 dB or more to performance in both directions, RX and TX -- way better investment.

    Landwehr's been around a long time, they're popular in Europe as are SSB, EME and other EU brands.
     
  8. N8SAN

    N8SAN Ham Member QRZ Page

    Got it.

    So for some reason as I was pondering this statement last night, is a preamp ONLY to overcome line losses? Meaning in a perfect world with 0 line loss, a pre amp is NEVER needed. In any situation? I mean EME, to local FM 3 mile simplex communications?

    Cool.
     
  9. WB3BEL

    WB3BEL Ham Member QRZ Page

    If your receiver had as good a noise figure as was ever possible, and had no losses between it and the antenna, then additional preamp would provide no performance benefit. The preamp in the receiver would be good enough.

    Now if you add transmission line losses between the antenna and receiver front end, then you might add a low noise preamplifier at the antenna to overcome the additional line loss.

    But most receivers do not have low noise front ends. So they can benefit from low noise preamplifiers if you live where there is low noise.

    In some cases it makes sense to put that preamplifier at the antenna. In some cases it makes less difference because the line losses are low or the ease of installation switching and protection of the electronics is easier done indoors. If you don't need every last dB of performance, then using a preamp in the indoor amplifier might be good enough. The most serious EME operators know they need every last bit of performance and they pull out all the stops.

    But beginning EME operators do not need every last bit of performance. When you are starting out, you most likely have less antenna gain and less EiRP than the big guns. You will likely be able to hear more stations than may hear you. A good external LNA can be beneficial, but you can have a lot of fun making some initial contacts without it if your feedline is short. It is better to make a few starter contacts with simple setups than get bogged down and lose interest before making the first contact because it is too complex.

    If you live where it is noisy, and lots of people do nowadays, then having a super low noise preamplifier will do little good.

    If you live where there are lots of strong signals nearby, and lots of people do, then having the lowest noise preamplifier may not help much as the preamplifier may be overloaded and create intermodulation and inband noise. So the proper amount of gain, filtering, and strong signal handling is much more critical in today's world than it was 10-20 years ago when some of these devices were first made. You need the right solution for your installation and environment. It is easier to figure out what your situation is, by getting your feet wet and see how it works out. You will know more and make more informed buying decisions.

    But the TE systems amp is a good starting point. The LNA is not super low noise, but it isn't terrible, it will help when used with the all band rigs like 857D or IC706 or IC7000 that many folks use for their first EME contacts. Your system might be very different if you already have a low noise and high performance transverter solution. You can calculate the system noise figure of a cascade of components if you are interested in the performance impact just Google "cascaded noise figure" and you will find online calculators and explanations. Or use the VK3UM tools.
     

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