[ARC5] ARC5 CW Question

[J Mcvey via ARC5]

I believe those receiver relays only served to put the side tone from the MD7 into the headphones. Is that really necessary if there is some crosstalk from the antenna relay?  I assumed the tx tone should be audible if the BFO is on in receiver.?

I am still wondering about  contact failure of K52  since they are keying ALL of the Tx B+ through K52 in the MD7.
Any guesses as to why they did it this way? Why not just key the oscillator?




On Monday, June 23, 2014 3:58 PM, "w4thq at cox.net" <w4thq at cox.net> wrote:
 


The Apollo program during the 1960's and 1970's had complex relay logic in the control systems of both the launch vehicle and ground support equipment.  Because of RFI-EMI problems, NASA required double-anode zeners across all 28 volt crystal-can relays.  We found this approach was effective.  We also discovered that the back-emf would "ring" and was not just one spike.  The drop out time was not significant in our application so I don't remember what it was exactly.
John  W4THQ
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