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| HDTV E-PHEMT LOW NOISE AMPLIFIERS (LNA'S) |
| TYPE 9255 Mains power supply for types 9254 and 9260 LNA'S DC output 8V + @ 100 ma. On/off mains switch with LED indicator. Very low hum and noise levels. Fully screened and filtered. 110/120V AC or 220/240V AC versions available. |
| TYPE 9252 Weatherproof enclosure for all LNA types with fully sealed cable glands,complete with mast fixing and internal thermal insulation. |
| Masthead Amplifiers It is common practice to use unprotected masthead amplifiers that rely on weather resistant protective boots pushed on over the connectors to help prevent water damage to the plugs and sockets. However this is not completely waterproof and moisture can cause bad connections in plug/socket assemblies, resulting in intermittent signal and/or increase of noise and a gradual loss of preamplifier output. This is expensive in time and money to trace and rectify. A better approach is to put the amplifier into a fully sealed case which uses waterproof cable glands. |
| SOME TYPICAL CUSTOMER COMMENTS ABOUT THE PHEMT LNA's I just wanted to get back to you guys to tell you that the UHF TV pre-amp I bought from you works extremely well and may have saved my marriage! I had been using a competitor's preamp (Channel Master Titan CM-7777) and our local CBS affiliate (broadcasting on UHF channel 46) was unwatchable (more cut-out then cut-in...) But now, with your pre-amp, the picture and sound are solid, all the time, without any drop-outs. I'm holding a BSEE degree and have worked as an RF Engineer for many years. Until I found your product, my wife couldn't understand why it was that I, a radio frequency engineer, couldn't fix the issue and provide her a way to watch CBS. It was a very difficult situation.... In the name of domestic tranquility, I can't thank you enough! (Gene F. USA) July 2009 - I installed my new 9261 PHEMT LNA at the weekend and I am delighted with the results. I am using it mounted at the masthead with an Antiference XG16BK antenna which covers the new USA DTV frequency plan (CH 14-51). Results are amazing, from my home in San Diego I can see 68 digital channels from Los Angeles (100+ miles away) and with a slight change in antenna direction signals from Santa Barbara over the horizon (200+miles away). With this amplifier you improve your NF by a good 10-12dB over the non amplified case and you can reach close to the theoretical reception limit. Excellent product - fully recommended. (Brian R. J. USA) We installed your UHF amp yesterday and were pleased with the results. We had been using a Channel Master amp, which did a very credible job, but your product is simply more effective. After losing several channels with the analog-to-digital switch in the U.S., your amp brought 5 ofthem back. In fact, we're now getting a channel that we never saw before. Your product has helped us expand our channel menu significantly. We're getting near 90% saturation levels from a few stations that didn't even show up before we had your preamp. Last night we were watching a program from 109 miles away! (Jon P. USA) I immediately installed the amplifier at my attic-mounted antenna. The signal strength as indicated by my television went from ~80% to 100% for all digital channels. No more occasional TV audio drop outs, and my FM radio reception is fantastic. (Steve M. USA) I am quite happy with the preamp. Very very high quality, excellent reception due to the lowest possible noise figure. I have 95% success in receiving Ch 13 at 41 miles away with a 2-edge reception and severe multipath. With the CM7777, I couldn't even get a digital lock on it. Pleased to advise that the LNA has arrived and has made a tremendous difference to my received signal. My HD TV is now watchable. I've finally tested the 9254 preamplifier with digital television, full success: - we get all the French channels now (in stead of half of them before)- we also get all the Swiss channels (none before). I received the 9253 yesterday. I must say that so far it is working phenomenally. It made a significantimprovement, and I am now receiving perfect pictures on all analogue channels and only very occasional picture break-up on digital channels. The preamp made a great improvement in quality of the received signals. I was able to receive one channel that is running on low power with the transmitting antenna mounted half way up on the tower about 90 air miles distance. I got this installed a few weeks ago. It made a huge difference. All our digital UHF stations are 100-140 km from us. They all come in perfect with no drop outs. Everything works great!! I can pick up HD signals from up to 70 miles away! I received the preamp system on March 31st. It was well packed and I was able to install in early April. I waited about a month before writing you this thank you note. I wanted to be sure that the system got a good testing before I let you know what I think of it. The preamp is wonderful. I use a large vhf/uhf antenna and a UHF antenna. The preamp is hooked up to the UHF antenna and I can rotate the system in all directions. Your preamp works great I can get over 50 HDTV channels with it.I can only get 38 with the other antenna and a different preamp. I have also almost no problems with HDTV breakup or overload. Thanks again. Preamp arrived today, works fine - super... Thank you. I have only tested two (2) of the preamplifiers to date. The units performed well enough to allow good reception (not perfect reception) of three TV stations which previously had only fair reception. This increases the number of truly watchable UHF stations to 9 of 24 detectable stations, in a bad location, with a Winegard 9885 antenna and a Channel Plus model DA-500A distribution amplifier. The distribution amplifier which has a quoted noise figure of 5.5 dB, a gain of 18 +/- 1.5 dB from 50 to 1000 MHz and a maximum output of 55 dBmV, is followed by a 4-way splitter. Previously, using a Winegard AC-4990 preamplifier the listed antenna and distribution amplifier, there were 6 truly watchable stations out of 22 detectable. Considering that the Channel Plus distribution amplifier contributes enough noise to increase the effective noise figure to approximately 1.3 dB, also considering cross modulation distortion in the Channel Plus amplifier combined with selectivity limitations of the TV tuners, the performance is impressive. Thank you. |
RESEARCH COMMUNICATIONS LTD
| ALL UNITS ARE NOW IN STOCK FOR SAME-DAY DESPATCH This is a range of very low noise television preamplifiers for long distance analogue and HDTV reception, especially suitable for fringe areas where drop-outs or low quality pictures are a problem. Don't put up with poor reception - get the best available. |
| CONTACT US: PHONE 01303 862842 (UK), 44 1 303 862842 (OVERSEAS). EMAIL: sales@researchcomms.com |
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| BANDPASS PERFORMANCE FIGURES FOR THE 9260 |
| TYPE 9260 |
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| TYPE 9254 A wideband version which covers both VHF and UHF. The unit has transient protection incorporated in both RF and DC paths. |
| LINK TO PERFORMANCE COMPARISON WITH OTHER PREAMPLIFIERS (SUPPLIED BY A CUSTOMER, G.L. DYBWAD, USA) |
| LINK TO 9260 PERFORMANCE FIGURES (SUPPLIED BY G.L. DYBWAD, USA) |
| The types 9260, 9261 and 9267 all combine very low noise with bandpass filtering to deal with interfering signals. The units have transient protection incorporated in both RF and DC paths. |
Operating guidelines
In order to obtain the very low noise figures offered we use PHEMT transistors. These are more
sensitive than Mosfets to pulse transients caused by storms. To help combat this we added low
frequency input filtering to the preamps which has proven to be very effective. Since we started
using it less than 2.5% of our customers have had to return units for repair.
An important consideration is that the antenna should be properly grounded to a copper spike. This
gives the transients a direct route to earth and reduces the likelihood of damage by at least 50%.
It's sensible to use a surge arrestor on the mains input, as you would to protect any equipment in
the home.
In order to obtain the very low noise figures offered we use PHEMT transistors. These are more
sensitive than Mosfets to pulse transients caused by storms. To help combat this we added low
frequency input filtering to the preamps which has proven to be very effective. Since we started
using it less than 2.5% of our customers have had to return units for repair.
An important consideration is that the antenna should be properly grounded to a copper spike. This
gives the transients a direct route to earth and reduces the likelihood of damage by at least 50%.
It's sensible to use a surge arrestor on the mains input, as you would to protect any equipment in
the home.
| The 9261 is now available with filtering to limit the top frequency to 700MHz in line with recent changes to digital broadcasting in the United States. All other specifications remain the same as the original 9260. |
| ***LATEST INTRODUCTION*** Type 9270 This very low noise, high signal handling capability amplifier is designed to increase the output of decoders to eliminate drop-outs and pixelization. It may also be used to compensate for long cable losses and for driving multi TV outlets. It is designed for indoor use only and is fitted with a feed-through for local DC supply. |
| FREQUENCY SELECTION CHART Choose the best LNA for your wanted reception. |
The type 9262 covers VHF and UHF channels with a frequency cut-off at
700 MHz. All other specifications remain the same as the type 9254.
700 MHz. All other specifications remain the same as the type 9254.