Sunday, November 10, 2013

ANAN-10 as a Transverter Driver

While aligning the G4DDK 4m Xverter, one thing I did discover on the ANAN-10 was that the output from the Xverter port is not vey clean.

Initially I set the output power on the power meter to 5mW (7dBm). I then hooked it up to the spectrum analyser  At  +7.8dBm at 28MHz from the XV port 2f was -24dBC, 3f was -20dBC. :-



I then backed off the output ~2dB to 5dBm and things improved dramatically. 2F was over -45dBC, 3F was -28dBC



The moral is;  dont push the PA on the Hermes board and always use a 28Mhz LPF.  To be safe the transverter was left set for 3dBm drive and an LPF will be built:-





2F is -48dBC, 3F is -32dBC.  For the record PA gain is set for 43.0 in power SDR and the xverter output coupling  was set to -19dB by choice of resistor values on the PCB (My hermes board came from TAPR which did not have the resistors or connector fitted for the transverter output). My setup was assembled shortly after ANAN-10 was launched. It used the Hermes board from TAPR and the PA board/Case from Apache-labs. The completely assembled version was on back order. The antenna port and the TX output port on the Hermes board are left unterminated which should make no difference as the PA is disabled but still providing a load.

2 comments:

  1. I thought the Anan-10/Hermes transverter output was specified as 0dBm output? At that level what does 2fc and 3fc look like?

    Mike G8TIC mike@tubby.org

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  2. If you get the recent ANAN-10 version from Apache-labs it is 0dBm. Mine is a very early version where the Hermes board came from TAPR with no transverter components and the PA/Case came from Apache-labs. I chose -19dB coupling. No mention on Apache-Labs site as to what their coupling currently is. My 3dBm +19dB =+22dBm is below the Hermes output stage rated power.

    For the record I measured mine at 0dBm out 2F was -50dBc 3F was still -32dBc

    It should be noted in the Hermes manual "Hermes_User_Manual_V1.17.pdf" by VK6APH. "Hermes is intended to be used with either a Power Amplifier, incorporating a Low Pass Filter (LPF), or an external LPF. The LPF should have 30 dB of attenuation at all harmonics of the transmit frequency. Do not connect Hermes to an antenna without incorporating a suitable LPF." This warning also applies to the XV output

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