Thanks for all the info Bob. But I'll still call the dial frequency for RTTY. Been doing it that was for over 30 years. And still using the same equipment - model 28ASR & KSR with a pair of Hal ST-6. Kenwood 520 ( no S or anything)
At 08:11 PM 5/17/2007, you wrote: >Hello John, > >Technology is changing this concept. I was recently "re-educated" on this >topic after returning from a ham radio hiatus. Like you, I grew up on the >principle you mentioned in your message, the transmit dial frequency is the >Mark frequency. > >This statement is no longer true or false! The answer to what your dial is >displaying is... "it depends"! > >In the old days, you would log and spot a RTTY station using the dial >frequency. This was because FSK was generated by switching a small capacitance >in and out of parallel with the main VFO capacitor. The Drake equipment (T4X, >TR4, and RV4) had a solder tab sticking out the side of the VFO "can" for this >connection. Your dial frequency WAS your Mark frequency and you shifted 850 Hz >or 170 Hz lower when the external capacitance was switched into the circuit. > >Today, the modern transceiver dial frequency may indicate the suppressed >carrier frequency, the Space frequency, the Mark frequency, or whatever you >want (in some cases). There doesn't seem to be any consistency among the >manufacturers, and in some cases within the same manufacturer. > >For a particular transceiver, you may be able to determine what the dial >frequency is from reading the operations manual, but sometimes not! You can >determine what a transceiver is doing by dialing in 28.100 MHz and transmit in >RTTY. Using an external frequency counter or receiver, you can then find your >FSK Mark carrier. It may be the same as the dial or not. It's a crap-shoot! > >Here are some examples why the newer technology has become a quagmire... > >My Kenwood TS-450 transceiver dial frequency IS the Mark frequency. This is >described on Page 38 in the operations manual. The dial displays the Mark >frequency, independent of the shift width or polarity. > >Likewise, the Ten Tec Orion II displays the Mark frequency when operating in >FSK mode. > >But there are a variety of other systems... > >My Kenwood TS-950S (and TS-950SDX) transceiver dial frequency displays the >SPACE frequency. This is described on Page 32 (Page 36) in the operations >manual. It shows the Space frequency independent of the shift width or >polarity. The dial frequency will be off by 170 Hz, hardly noticeable by most >operators. > >I also have an Icom 756 Pro III. The operations manual is vague regarding the >relationship between dial frequency and Mark frequency in this transceiver. I >can't find a specific statement in the book, but from experience it appears >the dial frequency is the suppressed carrier frequency. > >The Yaesu FT-920 throws yet another layer of configuration possibilities. This >transceiver allows you to program the dial frequency to display Mark, Space, >or the Center frequency! See Page 56 in the FT-920 manual which describes Menu >Item U-45. > >Likewise, the FT-1000MP provides menu 6-3 which allows the user to set the >transceiver displayed frequency to their choice. The default setting is to >display the Mark frequency. See Page 54 of the operations manual. > >With the introduction of computer soundcards being used to generate RTTY >tones, transceivers without FSK capabilities can now be used for digital >communications. In this case, the dial frequency is the suppressed carrier >frequency. The transceiver has no clue what tones are being broadcast through >its audio chain! > >The contesting (N1MM) and logging (DXKeeper) software I use in my station have >provisions to adjust to any method of FSK or AFSK frequency logging. Once you >know what your specific transceiver dial is telling you, you can adjust these >software so it logs and spots the exact Mark frequency. > >Welcome to the digital revolution! > >73 de Bob - KØRC in MN >
