On Sat, 31 Jan 2009 17:17:33 +0100, Lars E. Pettersson wrote:
>According to the R7 service manual, the voltage fed into the CM-1HF >mixer is 1 Vrms (+13 dBm). > >I'll se if can get some time tomorrow and check this. Interesting. The only thing I'm finding in the TR7 service manual is an input value to the upconverter board. My R7 manual has the value at input to the board, the value at the collector of the buffer (Q401), and the value at the input to the mixer. Based on what I am seeing, the LO level in the TR7 is slightly lower than the R7 - .9V P-P vs .44V RMS (1.24V P-P) at the input to the Upconverter board. This is amplified by Q404 and fed through an impedance matching network to the input of the mixer brick. Based on this, I can take a SWAG that the input to the mixer in the TR7 is around .723V RMS (+10 dBm), since the circuit in this area looks identical to the R7. I wonder if this bears out in the real world, or if Drake had some measurement errors. Thank for the info! 73 -Jim -- Ham Radio NU0C TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
