every 70 minutes - that's not really a job suitable to cron triggers - how about an Interval/Simple Trigger
trigger = TriggerBuilder.Create()
.WithIdentity("your-trigger", "your-group")
.WithSimpleSchedule(x => x
.WithIntervalInMinutes(70)
.RepeatForever())
.Build();
(you might need/want a .EndAt() clause as well)