88-108 MHz FM TUNERS
Receivers (tuner and
amplifier in one unit) are generally not suitable for DX. Dedicated quality FM
tuners that feature digital frequency display, wide/narrow IF bandwidth, high
sensitivity and image rejection are the main requirements for successful long
distance reception.
The Kenwood KT-6040 is potentially one of the most selective non-RDS FM tuners. This is mainly due to the KT-6040's series of eight filters. For example, here is the best filter combination for fringe DX work:
Wide: two SFE10.7MHY 110 KHz filters.
Normal: four SFE10.7MHY 110 KHz
filters.
Narrow: four SFE10.7MT 80 KHz filters + two SFE10.7MHY 110 KHz
filters.
Wide: FL1 (110) + FL2 (110).
Normal: FL1 (110) + FL2 (110) + FL3 (110) +
FL4 (110).
Narrow: FL5 (80) + FL6 (80) + FL7 (80) + FL8 (80) + FL3 (110) +
FL4 (110).
Installing Murata SFE10.7MF 50 KHz filters in the KT-6040 is not recommended. Several tests indicated that SFE10.7MF filters introduced excessive distortion, but with no apparent selectivity advantage.
As one progressively selects from wide to narrow IF bandwidth, more of the KT-6040's filters are switched in-line, so in the narrow position there are six filters in series, thus producing very steep skirt selectivity.
Preliminary tests indicate that unmodified KT-6040 (European version) and Onkyo T-9090 II tuners both have similar selectivity and RF image rejection. Once modified, the KT-6040's 80 KHz narrow selectivity is clearly superior to the T-9090 II's selectivity (four Murata 110 KHz filters).
When the 80 KHz filters are switched in, the KT-6040's weak signal sensitivity is high. The high sensitivity is probably mainly due to the KT-6040's 3SK121 GaAsFET first RF amplifier.
The KT-6040's selectivity is superior compared to all other tuners so far tested at my location. One example is how the KT-6040 is able to resolve weak daily aircraft scatter signals from 96.7 MHz 3ABC-FM Taralgon, VIC (407 miles / 655 km) - mp3 audio sample. The Onkyo T-9090 II (four 110 KHz filters) is unable to resolve 96.7 3ABC-FM. This is largely because of the adjacent 96.9 MHz 150 kw local (6km) Nova-FM signal.
Murata filters tend to have a slightly degraded selectivity curve on the high side of adjacent unwanted signals. This is also true for the KT-6040's 80 KHz filters. However, daily meteor scatter reception of 105.9 MHz 3ABC-FM Melbourne and 3ABC-RN Mildura next to local 150 kw 105.7 MHz 2JJJ-FM is not possible on any of my tuners, except the KT-6040 (80 KHz wide FM) and Icom R-8500 (15 KHz narrow FM).
One experienced UK DXer reports that the KT-6040 was more selective against adjacent channel QRM and thus allowing clear audio through from a weak signal that was only 100 kHz away from a 70+dB local station.
For European FM DXers seeking very high 100 KHz adjacent selectivity, a KT-6040, modified with 80 and 110 KHz MUrata ceramic filters, is probably the best option.
In 1991-92 the KT-6040 was officially released in Europe, Australia, and Canada. The KT-6040 isn't usually available second-hand in Australia. However, the KT-6040 appears fairly frequently on eBay Germany. Prices range from approximately 60-150 Euros.
Kenwood KT-6040 AM/FM tuner specifications (unmodified)
Rotary tuning dial.
25 kHz tuning steps
Eight IF filters
Tuning
range: 87.50 - 108.00 MHz
FM SECTION
50 dB Quieting Sensitivity
Mono - 15.3 dBf
Stereo -
37.2 dBf
Usable Sensitivity (DIN at 75 Ohm)
Mono: 0.7µV
Stereo: 25
µV
Selectivity (unmodified)
(DIN +/-300 kHz 80 dB (NORMAL))
(DIN
+/-200 kHz 80 dB (NARROW))
Image Rejection Ratio (at 98 MHz)
90 dB
IF Rejection Ratio (at 98 MHz)
110 dB
Spurious Response Ratio (at 98
MHz)
100 dB
AM Suppression Ratio
68 dB
Signal to Noise Ratio
(DIN weighed at 1 kHz)
Mono - 83 dB (85.2 dBf input)
Stereo - 76 dB
(85.2 dBf input)
Kenwood KT-6040 Photo.
The Onkyo T-9090 was replaced by the T-9090 11. The T-9090 11 is
superior to the earlier T-9090 with regard to selectivity, tuning steps, antenna
inputs, remote control, and number of memory pre-sets.
US TV and FM DXer Jeff Kadet compared his Onkyo T-9090 II to the
near-legendary McINTOSH MR78, and found that the selectivity and sensitivity on
both tuners were virtually identical. However, the Onkyo T-9090 II was
preferred, because it includes digital frequency readout, 20 memory pre-sets,
and 25 KHz tuning steps.
A DXer living in Sydney, Australia, once received a 1,400 mile FM station via
tropospheric ducting from New Zealand. Receiving equipment consisted of just an
ONKYO T-9090 II tuner and indoor T-ribbon dipole!
Onkyo T-9090 II
specifications
Tuning range: 87.5 - 108 MHz
25 KHz tuning steps.
Usable sensitivity:
Mono: 0.8uV (S/N 26 dB, 40 KHz Deviation.) DIN
Stereo: 20uV, (S/N 46 dB, 40
KHz Deviation.) DIN
50dB Quieting Sensitivity: Mono: 15.8dBf, 1.7uV
Stereo: 37.2dBf, 20uV
Capture Ratio: 1dB
Image Rejection Ratio:
100dB
IF Rejection Ratio: 100dB
Signal -to -Noise -Ratio: Mono: 95dB
(IHF)
Stereo: 85dB (IHF)
Selectivity: 80dB DIN (+/-300 KHz, IF: super
narrow)
95dB (+/-400 KHz)
The Onkyo T-4711 FM tuner is also highly recommended. This tuner
has similar performance to the T-9090 II, but with the added bonus of a tuning
dial. Minimum 25 KHz tuning steps is another desirable feature. The T-4711 is
now only available second-hand.
Because the Onkyo T-4711 has only four filter positions in the super narrow
bandwidth position, the selectivity is down compared to the Onkyo T-9090 II
(five filters), or Kenwood KT-6040 (eight filters).
The Onkyo T-488F was initially released about 1993. Performance is very similar to the T-9090 II. However, unlike the T-9090 II, RDS is also included.
The Sony ST-SA5ES FM tuner has two 75 ohm antenna inputs, 100dB image rejection, RDS capability, rotary tuning dial, digital signal strength meter, and good sensitivity.
Because the ST-SA5ES has only four filter positions in the super narrow bandwidth position, the selectivity is down compared to the T-9090 II (five filters), KT-6040 (eight filters).
50 KHz minimum tuning steps is also a slight disadvantage.
Sony ST-SA5ES technical specifications
Tuning range: 87.5 - 108 MHz (50 KHz steps)
Sensitivity - usable 10.3 dBf
0.9 uV (75 ohms), 1.8 uV (300 ohms)
Sensitivity at 50dB 38.5 dBf 23 uV (75
ohms), 46 uV (300 ohms)
Harmonic distortion Wide: 0.004% (mono)
0.0075%
(stereo)
Narrow: 0.04% (mono)
0.07% (stereo)
Stereo seperation Wide: 70
dB
Narrow: 50 dB
Selectivity Narrow: 65 dB (+/- 300 KHz)
Wide: 70 dB
(+/- 400 KHz)
Image rejection ratio 100 dB
One current production RDS tuner, which is highly recommended by Girard Westerberg, is the Denon TU 1500RD. The TU 1500RD is currently $699.00, and also available in Australia: http://www.duratone.com.au/html/products/denon/tu-1500rd.htm
European DXers generally use the following FM tuners:
Kenwood KT-6040.
Onkyo T-4711.
Onkyo T-9990 (European version of the
T-9090 II).
Onkyo T-4970.
Sony ST-SA3ES
Sony ST-SA5ES.
FM
antennas
The Antenna Performance APS-13 is probably the best commercially produced
antenna currently available for 88-108 MHz deep fringe FM reception. The forward
gain is 10dBd, and average front to back ratio is 30dB! For futher details,
visit the Antenna Performance web
page.
The Antenna Performance APS-9 is smaller, hence more economical and practical for DXers.
USA DXers tend to use the following range of 88-108 MHz FM antennas:
APS-13 or APS-9 log-periodic FM antennas.
Chromstar CA-6065, 9 element
log-periodic antenna.
Antennacraft (Tandy) FM-10, 10 element
log-periodic/yagi antenna.
Channel Master Stereo Probe 9, 9 element
log-periodic/yagi antenna.
Many UK and European DXers use the Triax FM-8, 8 element 87-108 MHz yagi. This antenna features two reflectors, one dipole, and five directors. Triax is located in Denmark. Fuba (Germany) also make a 8 element yagi, with a very similar design to the Triax FM-8.
Australian FM DXers use the following range of 88-108 MHz FM antennas:
Matchmaster FM-G8, eight element 88-108 MHz yagi.
Hills 3-4-5, eight
element 88-108 MHz FM/band 2 TV yagi.
Portable
Radios.
Another excellent AM FM DX performer is the Grundig YB-400 or YB-400PE. For
more information, go to http://www.dxing.com/rx/yb400.htm
One portable radio that has received good reports from European FM DXers, is
the Grundig Satellit 700. Some
DXers have modified this radio with Murata 110 KHz filters. Murata SFE10.7 MT 80 KHz, SFE10.7MY-A 110 KHz, and SFE10.7MJA10 150 KHz
filters are currently available in small quantities from the FM and TV DX plaza.
Car radios for
FM DX
I received the following message from Eddy, Canada:
"The Sony srf-s83 is a personal walkman type radio which delivers better
selectivity and sensitivity than ANY other personal radio by Sony, Panasonic,
Radio shack, etc. It's one of the best personal radios on this planet (trust me,
I've tried at least 10 models from various manufacturers). See the review at: http://www.geocities.com/toddemslie/www.simplyradios.com
for another sensitivity opinion"
Is the Icom
R-7000 suitable for 88-108 MHz FM DX?
Television DX
Receivers
Choosing a receiver for Television DX is quite difficult
because most TV sets were initially only intended for local reception. I have
found only one TV tuner, which was especially designed for reception of long
distance Television reception.
HS Publications (7 Epping Close, Derby, DE22 4HR, England), sell the D100 TV
tuner/converter. This tuner uses a MOSFET varicap tuner covering 45-860 MHz. It
also features variable IF bandwidth to improve selectivity. The D100 also
converts the TV audio to 95-100 MHz for use with a FM tuner. TV audio can also
be received on 36 MHz using a scanner. A excellent combination is a D100, and
Icom R7000 modified with MURATA SFE10.7 MHY-A, 110 KHz filters. The output
frequency of the D100 is at UHF. Veteran TV DXer Bob Cooper has also used the
D100. The D100 is used extensively in Europe, and has received rave reviews from
DXers.
MULTI-STANDARD
NTSC, SECAM, AND PAL TV SETS It is next to impossible to find TV sets which are both multi-standard, and
also suitable for DX TV. The following extract from will explain why: "At first, a multi-system TV receiver may seem the ideal choice for TV DX-ing
but it does not address the complex reception problems encountered, particularly
in VHF Bands I and III where interleaved channel allocations
exist. Multi-standard TV sets are likely more common in Europe, because of
neighboring countries that use different standards. For example, if you lived in
Switzerland, you would be able to receive pictures from France, Germany, Italy,
and Austria on a daily basis. The German companies Grundig and Blaupunkt make quality VHF/UHF
multi-standard TV sets.
TV DX
antennas
Channel Master 1126, 10 element chA2-A6 yagi. ChA2-A13 wideband USA VHF DX antennas:
Channel Master 3600A. Australian DXers have a limited choice regarding TV antennas suitable for DX work:
Hills 205/02, 5 element 45-70 MHz yagi. The CLP5130 log periodic 50-1300 MHz antenna is currently very popular for DX
TV and FM reception in Japan. The official web site for the CLP5130 is at http://www.cd-corp.com/eng/ama/5130.htm
Links
Every serious
TV and FM DXer should use a good quality scanner. The Icom R-8500, 7100, and
7000 are all excellent. The AOR AR-5000 is very good, however it is also very
expensive.
If you are serious about using a scanner for FM DX, I would
remove the stock wide ceramic IF filters, and install some 110 KHz SFE-MHY-A
Murata IF filters.
When I
first tried my unmodified R7000 for FM DX, I was disappointed by the FM wide
selectivity. This is because the R7000 only used (1) 230 KHz, and (1) 150 KHz
Murata ceramic filters. With this arrangement, I found that the adjacent (+/-200
KHz) selectivity was relatively poor.
I replaced the stock filters with
two 110 KHz Toko ceramic filters. The selectivity was considerably better, and I
also found that tuning +/- 200 KHz of locals signals produced mainly white
noise.
The only disadvantage was 1-2 dB reduced sensitivity. This is
because the Toko filters had higher insertion loss. This did not concern me
because I use a tunable 88-108 MHz Mosfet pre-amp, which compensates for any
slight losses in the IF stage. The pre-amp also partially compensates for the
R7000's untuned RF front-end. In city areas, you will find several images of
local stations across the dial. A tuned pre-amp, or bandpass filter will improve
the R7000's image and overload problems.
My next project is to replace
the two Toko 110 filters with Murata SFE10.7MHy-A 110KHz filters. The Murata
filters typically feature lower signal loss and improved shape factor.
I
once compared my modified R7000 to the TEAC T-515 FM tuner (60dB +/- 300 KHz
selectivity). The R7000 was better, though not as good as my Onkyo T-9090 11 (80
dB +/- 300 KHz). I would estimate that the R7000, with two 110 KHz filters has a
selectivity specification of ~ 70dB +/- 300 KHz.
HS Publications TV
FM DX 2003 equipment catalogue - home of the D100 DXTV tuner PDF
version.
Multi-system receivers are mainly intended for the traveler or for use
in countries where more than one TV system is available. The main drawback with
such a receiver for DX-ing is its inherently wide vision I.F. bandwidth, which
is necessary for high-definition pictures.
Although good results may be
obtained with local-quality signals, the shortcomings of such a receiver begin
to show if attempting to resolve anything other than a strong solitary
signal.
Other drawbacks associated with current TV receiver trends include
video channel muting, when the signal level is considered inadequate for
domestic viewing, plus complex set-up menus and tuning arrangements.
The
enthusiast relying on an `up-converter' device(VHF to UHF frequency converter)
for viewing VHF signals via a UHF TV receiver will also experience shortcomings
due to the use of the wide vision I.F. bandwidth of the TV. Not to mention the
problem of locating the channel in the absence of a signal!" 
Anthony Mann (Perth, Western Australia),
used a CX28 Crossfire from 1971-1998, with remarkable results. His overseas TVDX
included: England, Sweden, Finland, Germany, Russia, China, American Samoa, and
other countries.
USA TV DXers use the following antennas for 55-83 MHz
chA2-A6 low band DX:
Wineguard (Prostar) YA-1026,
10 element chA2-A6 yagi.
Wineguard (Prostar) YA-6260, 6 element chA2-A6
yagi.
Antenna Craft (Tandy) Y10-2-6, 10 element chA2-A6 yagi.
Channel Master 3601A.
Chromstar
CA-5254.
Antennacraft CS-1100, 33 element log periodic.
Antennacraft
CS-1000, 30 element log-periodic.
Hills DL/4, ch0-12 45-230 MHz log
periodic.
Antennas and
receivers in current use by US TV and FM DXers. Scanners and
receivers for DX TV monitoring.
