Amplifiers with over current protection or sensitive FET transistors, may not like a stock D201. You know, the engineers left the DC shunt choke, out of the PA design for the final tube??? Every time you key, the DC blocking cap charges to almost 400 VDC, through a path that includes whatever is connected to the antenna connector! The DC shunt choke that would normally provide a safe path to charge through, is missing. This causes other coupling caps in external amplifiers, to also spike back and forth, between a charge and discharge state.
When you unkey, the relay in the Tram connects the antenna to a RX input Transformer, with a DC grounded primary. That insures a large discharged current to external amplifer, input coupling caps. The transient spikes created, can burn up sensitive gates or, cause protection circuits like "The Triode Board", to go into a Grid overload condition, each time the Tram switches form TX , to RX.
Amplifiers without protection, may experience internal tube arcs or, blown gate junctions, when exposed to the Tram's switching transients. The cure is to install a DC shunt choke, right across the SO -239 connector on the Tram. 10 uh at 500 ma, about the size of a 2 watt resistor, works fine here.
Now "The Triode Board", functions just like it did, before it met the Tram. Don't put your fingers on the stock output of a D201. It won't be just the few watts of RF you might expect. You will feel that 400 volt spike!
When you unkey, the relay in the Tram connects the antenna to a RX input Transformer, with a DC grounded primary. That insures a large discharged current to external amplifer, input coupling caps. The transient spikes created, can burn up sensitive gates or, cause protection circuits like "The Triode Board", to go into a Grid overload condition, each time the Tram switches form TX , to RX.
Amplifiers without protection, may experience internal tube arcs or, blown gate junctions, when exposed to the Tram's switching transients. The cure is to install a DC shunt choke, right across the SO -239 connector on the Tram. 10 uh at 500 ma, about the size of a 2 watt resistor, works fine here.
Now "The Triode Board", functions just like it did, before it met the Tram. Don't put your fingers on the stock output of a D201. It won't be just the few watts of RF you might expect. You will feel that 400 volt spike!
