[WriteLog] W5XD/K5DJ multi-keyer for SSB and AFSK

[William Q Meeker]

I have been using the W5XD/K5DJ multi-keyer and Writelog on CW for 
the past year. I am now moving toward hooking it up for SSB and AFSK.

I have read a huge amount of related material in the Writelog web 
pages, at K9JY, the Writelog archives, and the lots of stuff that 
comes up in Google searches. Most suggestions are very consistent 
(e.g., the need for isolation in the audio lines to avoid ground loops).

The SO2R W5XD/K5DJ multi-keyer set up diagram (SO2RMKSUD) 
(www.writelog.com/support/wlso2r.pdf) seems simple enough but, but I 
found departures from the diagram in my reading. I realize that there 
are different kinds of sound cards and different ways to connect a 
sound card to a radio. The large number of combinations has me worried.

I have a few specific questions.

1. For the W5XD/K5DJ multi-keyer/Writelog, the station mic is plugged 
into the mic-input of the computer's sound card. I have read and 
heard that sound cards are designed for inexpensive condenser 
microphones and that some kind of preamp is needed because of the 
low-level output for a high-quality dynamic mic (I am using Heil 
HC-4/HC-5). In ham-related applications the only references to a 
preamp that I saw suggested that it was not needed and could cause 
RFI problems. What should I do here (I do not think that my sound 
card has a preamp)?

2. The SO2RMKSUD has the sound card line out going (through isolation 
transformers) to the Mic inputs of the radios (one channel for each 
radio). I have read that a voltage divider/impedance matcher is 
needed here (although it is not on the SO2RMKSUD). Would it make 
sense to have the sound card line out go, instead, to the radio line 
in (perhaps avoiding the need for the voltage divider/impedance matcher)?

3. Similarly, should the sound card line in go to the radio's line 
out (one radio on each channel), as suggested by the SO2RMKSUD? The 
SO2RMKSUD does not suggest isolation transformers in these lines. Why 
not? Seems like it would be a good idea to me, just to have the 
electrical isolation.

Bill
K0KT






William Q. Meeker
Department of Statistics
304C Snedecor Hall
Iowa State University
Ames, Iowa 50011
Phone: 515-294-5336
Fax: 515-294-4040
Home Fax: 515-232-1323
www.public.iastate.edu/~wqmeeker