Hits:  since 20050614

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"Corrected" Tropospheric Path Loss = TX ERP [in dBm] + RX Ant. Gain [dB]  -  RX feed line loss [in dB, often negligible] - antenna height loss  [in dB, see graph below] -  -145 dBm [CW RX sensitivity level] - band noise above 290 K [in dB, from upper graph per  your location's man-made noise level]

It is expected your RX system Noise Figure is substantially below 3 dB! (RX k curve)

Using the calculated Corrected Tropospheric Path Loss value, you are able to determine the approximate maximum range (CW mode) from upper graph (signal received 50% of time).

Note: the "Corrected" Path loss here is used include effects that reduce RX S/N ratio specially on 50 and 28 MHz due to higher noise levels on those bands to get the true range and not just pure path loss. If you need only the path loss for shorter range to estimate signal level when S/N is not an issue, do not correct for band noise!

Note: Range can be reduced by lower TX and/or RX antenna's height,  terrain and other obstructions and by factors such as poor RX system Noise Figure, higher local noise level which to some degree, can be corrected using the graphs.

OH5RBG 70.033 MHz 5 W beacon

OH5RBG's 70 MHz  beacon's ground wave coverage. Computed signal strengths (S-units) with 8.5 dBd RX antenna at 25 m above average ground level with unobstructed take-off, S 1 = 0.2 uV (-121 dBm) @ RX input.
 

The 70 MHz beacon was built during fall of 2009 with latest technology: USB-controlled synthesizer, PIC-based PC-configurable keyer and MMIC driving the FET PA. The basic scheme works for all bands from 28 to 70 MHz with just modifications to driver LPF and PA stage coils and capacitors - the single-ended FET PA is narrow-band type. Using the 175 MHz application sheet for RD06HVF1 FET, the beacon can be built for 144 MHz operation also. 432 MHz model would need different version for the synthesizer chip - the faster LVDS reaching up to 910 MHz.

The first built beacon module was for 40 MHz, but uncertain and troublesome licencing caused a rebuild to 70 MHz (took some 2 h) which has been a ham band in Finland since 4th Nov. 2009. The enclosure holds the 70 MHz beacon TX module with G4JNT keyer and a 4.5 A SMPSU. FET PA feeds some 5 W to a horizontally polarized low-gain (7 dBi) antenna (Aerial AV1462-70) beaming Az. 232° (SW for sporadic-E propagation) mounted on a cellular tower on a hilltop 131 m + 8 m ASL and delivering 15 W of ERP.

In detail, the synthesizer, which is configurable for any QRG from 3.5 to 260 MHz in 1 Hz steps (and for exact FSK shift) via the USB connection, delivers a 0 dBm (square wave) fed via 2- section LPF to ERA-5SM MMIC amplifier. G4JNT RS-232-configurable PIC-keyer keys the ERA-5SM stage. The +16 dBm drive feeds a low-cost SWR tolerant Mitsubishi PA FET delivering 5 W RF-output. The output is filtered with several LPF stages, one for UHF for added attenuation on cellular frequencies (harmonics are attenuated by 119 dBc on 900 MHz UMTS band). Total current is monitored with a 2 A analog panel meter. The antenna output circuit has a 230 V gas-disharge tube, 2 kV series capacitor and antenna connector & case bonded to site ground bar.

 This TX uses IC XO followed by MMIC amplifier stage driving RD16HHF1 10 W FET power amplifier. The MMIC is CW keyed with a G4JNT keyer.  With 2.3 dB cable lossses, 6.5 W of RF is fed to horisontal dipole at 5 m AGL. The ID "vvv OH5TEN KP30HV" is send  every 50 seconds and in between 30 seconds of carrier. Ambient temperature varies from +10 °C to +25 °C (winter/summer).
 

This is after the antenna was changed to H-pol dipole E-W and relocated away from the station:
OH5TEN's 28.230 MHz  beacon's ground wave coverage. Computed signal strengths (S-units) as received with a 6 dBd antenna at 25 m AGL.
 
 

5.7 GHz: GPSDO (108 MHz) indoors at room temperature, drives ODU via LPF and 12 dB attenuator pad, an ERA-5SM MMIC stage followed by 120 MHz BPF and is +Vcc CW keyed from G4JNT keyer.
14 V DC from 4 A SMPSU is fed to ODU via Lo coaxial cable via bias-Ts, ODU drawing about 1.11 A current at key-down. The mutiplier is a DB6NT kit (5.7 GHz modified link TX kit). 5.7 GHz PA is a commercial Walkera PA5801 Pout: 1.55 W.
Exact frequency of this beacon is  5760 934 992 Hz.

10 GHz: GPSDO (108 MHz) indoors at room temperature, drives via LPF and 6 dB attenuator pad a +Vcc CW keyed (G4JNT keyer) ERA-5SM MMIC stage, followed by 108 MHz BPF. The 14 V DC power from shared SMPSU is fed to ODU via Lo coaxial cable with bias-Ts,
 ODU is drawing about 1 A current. Multiplier is a DB6NT kit (10 GHz BCN TX unit). 10 GHz 1 W GaAs-FET PA is from Dirk Fisher Elektronik. Exact frequency of this beacon is  10 368 935 040 Hz.

ODU electronics is build inside an ex. Allgon 900 MHz City GSM base station panel, also enclosing two 1 m long home-made waveguide slot antennas, one each for both bands. They are made from std aluminium profiles, slots milled with Dremel-type hand tools and
 delivering horizontal polarisation, very flat beams, 13 dBd (5.7 GHz) and 16 dBd  (10 GHz) of gain illuminating 100° wide sectors centered at WSW with 5° of up-tilt to climb over an adjacent hill and treetops there.
 Because of the tilt, these beacons work better on rainscatter propagation, than on tropo. Except for the opening towards WSW, there is substantial treecover, but also some narrow gaps to S and SSW.
The 10 GHz coverage map is modified to account for the trees blocking the takeoff.

OH5ADB (QRT) received in KP30HV on 144.455 827 MHz with 19.7 dBd antenna and 1.4 dB feed losses at -117 dBm.