EMRFD Message Archive 5897

5897 2011-03-09 08:34:44 ha5rxz Mixer Confusion Message Date From Subject I have been looking through the data sheets for Minicircuits mixers and I must admit to some confusion because of the way the data is formatted. If I use (for example) an SRA-1+ device this is a 'Level 7' mixer with 7dBm expected at the Local Oscillator port. No mention is made of the expected level into the RF port. 1) Can I also feed 7dBm into the RF port as well when the device is used as a transmit mixer, for example 45 MHz @ 7dBm into the RF port and 59 MHz @ 7dBm into the RF port to generate a 14 MHz output? 2) Mixer Conversion Loss at HF frequencies is about 6dBm. If I feed two 7 dBm signals into the device should I therefore see 1 dBm @ 14 MHz before filtering? Is there a formula to work out output power given known power into the two inputs? Obviously when these devices are used as receive mixers there is no problem with power levels. Peter HA5RXZ be beware of the 1 dB comnpression point, which from memory for a 7 dBm LO type is in the range of +1 dBm for the RF port. This means that for a +1 dBm RF signal You get 1 dB less output power as for signals which are far below this point, Example: RF -10 dBm in, -16 dBm out "loss" = 6 dB RF +1 dBm in , loss then 1 dB above 6 dB i.e. 7 dB results in +1 - 7 dB = -4 dBm For feeding two equal signals in, I am not so sure for the moment, may be You have to take into account the PEP value (peak envelope power) which is 6 dB above the single tone. So for two 1 dBm tones, You are deep into compression, + 1 dBm PEP (i.e. - 5 dBm/tone) would give You -4 dBm PEP, or -10 dBm/tone in the output.. 73 Henning Weddig DK5LV Am 09.03.2011 17:34, schrieb ha5rxz: > I have been looking through the data sheets for Minicircuits mixers and > I must admit to some confusion because of the way the data is formatted. > If I use (for example) an SRA-1+ device this is a 'Level 7' mixer with > 7dBm expected at the Local Oscillator port. No mention is made of the > expected level into the RF port. > > 1) Can I also feed 7dBm into the RF port as well when the device is used > as a transmit mixer, for example 45 MHz @ 7dBm into the RF port and 59 > MHz @ 7dBm into the RF port to generate a 14 MHz output? > > 2) Mixer Conversion Loss at HF frequencies is about 6dBm. If I feed two > 7 dBm signals into the device should I therefore see 1 dBm @ 14 MHz > before filtering? Is there a formula to work out output power given > known power into the two inputs? > > Obviously when these devices are used as receive mixers there is no > problem with power levels. > > Peter HA5RXZ > > Hello Peter, This issue has been investigated in the past. I have a source that states a maximum double tone rf input of -8 dBm for a DBM with +7 dBm LO power. That is for 40 dB IMD products in regard to the carrier. If I remember correct, it is safe to stay at - 10 dBm maximum rf input power. With 6 dB loss, the output will be -16 dBm and you will need quite a bit of amplification behind the mixer. 73, Roelof Bakker, pa0rdt