Modifications for the ICOM - RogerK

New component values:C334 82pF C333 1.2pF L99 180nHL101 180nH L100 100nH C329 3.9pFC332 10pF C331 2.7pF C330 10pFCaps in 0603 size, Farnell or Johanson. Inductors in 1008CS size, Coilcraft. The result is given in plottxnew.pdf. The measuredfilter response was even better; there was a resonance bump at 120 MHz and 150 MHz.The power levelling did not work so good outside of the ham bands. This is due to the frequency dependent detection circuit onthe PA board. The Tx power was +2dB at 120 MHz and +8.5dB at 165 MHz.Spurious emission increases at the Tx band edges, 120 and 170 MHz, to about -30 dB. The VCO1 to VCO0 switch, below 120MHz for my 706, increases the problem since the doubler output power is a bit low at the band edge.This modification is read 4213 times.top of page03-03-2002(IC-706) Adding an extra RX-only port in the Icom IC706Author: Jaap van oosten - pa0oos@qsl.net.MODIFICATION.NETThis is usefull when using a big PA and or for RF bandpass filters. My FT102 + transverter recently broke down So i now use theIC706. The sensitivity of the IC706 is not what I was used with the transverter. There is raise of noise when connecting theantenna so in fact it is just sufficiënt.Using the IC706 with an external PA you might need a lownoise preamp. But it is not so easy to use because without extraprotection relays it can, and sure will be destroyed by the driving power of the IC706.The best solution is having an extra RX–only input like most bigger tranceivers have. This way the preamp can be placed directbehind the first antenna relay and the output of it Goes to the RX-only port. The best place for this antenne relay of course is asclose as possible to the antenne to avoid extra cable loss however not so practical.Adding a separate RX port is an easy and clean modification. There is a spare opening in the backpannel where an extra BNCconnector can be placed. Extra rings are used to fit because the hole is to big for the BNC. Then this BNC must be connected toJ1 (rx) point found at the back of the filterunit.The filterunit is situated top-backside. After removing 5 screws the board can be moved up at the backside Just enough to mountthe BNC underneath it. It is not needed to remove it completely that would be a problem because of all connections to it.