SDRplay Community Forum

Hi Lou, excellent diagram which fills the bill for a failsafe antenna switch. I would only add 0.01 to 0.1 uF (not critical) bypass capacitors across the 12 V power supply input and between base and emitter of Q1 and Q2 to avoid malfunction due to excess RF rectification. I would also add another 0....

SIMPLE AND RELIABLE RSP RECEIVER PROTECTION The schematic diagram is shown below. The switch is built around a miniature relay with contacts rated 10 A @250 VAC. +12V supply voltage is connected to terminals B and C and is monitored by LED D2, to warn about the absence of supply voltage which would...

SIMPLE AND RELIABLE RSP RECEIVER PROTECTION The RSP play specification for RF input is: 0 dBm - 1 mW - permanent maximum. +10 dBm - 10 mW - short periods. In a 50 Ohm system, 0 dBm correspond to an RMS voltage of 0.223 V and to a peak-to-peak voltage of 0.632 V. +10 dBm correspond to an RMS voltage...

SIMPLE AND RELIABLE RSP RECEIVER PROTECTION

Please see next post, this done for amendment purposes.

RECEIVING SYSTEM ASSESSMENT @ 29 MHz Noise Floor assessment for the 28/29 MHz band is as follows: Wavelength Wl @ 29.0 MHz: Wl = 300/21.5 = 10,34 m Ratio L/Wl: R = 135/13.34 = 13 Figure 1 in the cited reference does not go all the way up to 13 length to Wavelengt ratio, so I consider a worst case g...

RECEIVING SYSTEM ASSESSMENT @ 21.5 MHz Noise Floor assessment for the 21 MHz band is as follows: Wavelength Wl @ 21.5 MHz: Wl = 300/21.5 = 13.9 m Ratio L/Wl: R = 135/13.9 = 9.7 From "Beverage Antenna gain Vs. wavelength", at the extreme of Figure 1 in the cited reference, we extrapolate: G = +7.5 d...

Just one word of warning: in general diodes and receiver front ends do not go well together, especially with SDR specimens, which have little or no narrowband preselection. If you live in an area with no strong local signals, then a diode switch could fill the bill, once it is understood that interm...

RECEIVING SYSTEM ASSESSMENT @ 14 MHz Noise Floor assessment for the 14 MHz band is as follows: Wavelength Wl @ 14 MHz: Wl = 300/14 = 21.4 m Ratio L/Wl: R = 135/21.4 = 6.3 From "Beverage Antenna gain Vs. wavelength", Figure 1 in the cited reference: G = +5.0 dB referred to the isotropic. Balun inser...

RECEIVING SYSTEM ASSESSMENT @ 7.2 MHz Noise Floor assessment for the 7.2 MHz band is as follows: Wavelength Wl @ 7.2 MHz: Wl = 300/7.2 = 43 m Ratio L/Wl: R = 135/43 = 3.15 From "Beverage Antenna gain Vs. wavelength", Figure 1 in the cited reference: G = +1.5 dB referred to the isotropic. Balun inse...

Hi Len, The RSP play specification for RF input is: 0 dBm - 1 mW - permanent maximum. +10 dBm - 10 mW - short periods. 0 dBm correspond to an RMS voltage of 0.223 V and to a peak-to-peak voltage of 0.632 V. +10 dBm correspond to an RMS voltage of 0.707 V and to a peak-to-peak voltage of 2V. Therefor...