[TenTec] Omni QSK Relay Delay

[John Unger]

Jim -

When I was building an outboard QSK box for my Drake L-4B to interface with my Omni VI, I found that looking at the timing with a 'scope was essential! I just had to be able to see when things were happening to make sure that no hot switching was possible. I set the trigger on key down and then looked at when the other switching events occurred. I think that is the only safe way to do things.

Good luck!

73 - John, W4AU


At 14:28 10/31/01 -1000, you wrote:
>Hi,
>
>Have had to replace the input T/R relay on my amp (Henry).
>Relay is a small Guardian electromechanical unit,  probably
>takes 10 or so milliseconds to switch.
>
>Suspect the replacement was because of burned contacts
>from "hot switching".   The Omni was deaf at key up;  the input
>relay had not returned to the receive side.  Couple of key
>taps,  or PTT pushes would return "hearing" on rcv.
>
>The Omni VI+,  uses a mechanical relay
>to signal the amp's T/R switching relays. Figure at least 10 ms 
>for this relay to operate.  Then RF output  appears less than 
>5 ms after the contact closure since per the ARRL lab tests,  
>my Omni keying has about a 15msec delay between key down 
>and RF output, and 17 msec delay between key up and the
>RF stopping.
>
>5 to 7 milliseconds is less time than the amp Guardian input relay 
>needs to operate.  Therefore when the input relay contact opens, it 
>is carrying RF current, and so it will arc as it opens.  Every time. 
>
>Prowling about in the Omni manual,  I just discovered the news that
>the OSK Slow relay delay is adjustable over a range given as
>01 to 15 (what,  milliseconds?).  Anyway,  following the manual
>instructions,  have checked and found my rig,  at the moment
>is at "position" 07.  If I increase this to 15,  will both of the amp
>relays not open for at least 15 milliseconds after key up?  Even
>then that might not be long enough if the Omni requires some
>17 mS for RF to shut down after key up.  And, would RF not 
>"leave"  the Omni until 15 mS after key down in this setting;
>probably faster as this is called "relay delay".
>
>Maybe I just don't understand what is going on here.  Anyone
>use the Ameritron QSK-5 unit along with some other non-
>Ten Tec linear with their Omnis?  Maybe that unit would solve
>my problem.
>
>Any ideas?
>
>73,  Jim  KH7M
>
>
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