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
BAND
UHF
FREQUENCY
EU 470-862 MHz. (CAN 470-800 MHz.)
NOISE FIGURE
0.4 dB.
GAIN
23 dB.
FLATNESS
+/- 1 dB.
MAX. OUTPUT
127 dB microvolts.
MATCHING
Return loss 14 dB.       V.S.W.R. 1.5:1
IMPEDANCE
75 ohms.
CONNECTORS
F sockets.
POWER
+8V. DC @ 73 ma approx.
DIMENSIONS (ins)
L 2 x W 1.5 x H 1.25 ins approx.
DIMENSIONS (mm)
L 52 x W 48 x H 30 mm approx.
CASE
Diecast aluminium.
FINISH
Natural.
FREQUENCY
ATTENUATION
FREQUENCY
ATTENUATION
50 MHz
-80 dB.
600 MHz
0 dB.
100 MHz
-70 dB.
700 MHz
0 dB.
200 MHz
-50 dB.
800 MHz
0 dB.
300 MHz
-30 dB.
900 MHz
-20 dB.
400 MHz
-13 dB.
950 MHz
-30 dB.
500 MHz
0 dB.
1000 MHz
-54 dB.
BANDPASS PERFORMANCE FIGURES FOR THE 9260
TYPE 9260
BAND
VHF/UHF
FREQUENCY
50-800 MHz (USA) 50-862 MHz (UK)
NOISE FIGURE
0.4 dB.
GAIN
23 dB.
FLATNESS
+/- 1 dB.
MAX. OUTPUT
127 dB microvolts.
MATCHING
Return loss 14 dB.       V.S.W.R. 1.5:1
IMPEDANCE
75 ohms.
CONNECTORS
F sockets.
POWER
+8V. DC @ 73 ma approx.
DIMENSIONS (ins)
L 1.5 x W 2 x H 1.25 ins approx.
DIMENSIONS (mm)
L 48 x W 52 x H 30 mm approx.
CASE
Diecast aluminium.
FINISH
Natural.
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.
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.