29-07-2015, 07:40 PM
I too would vote for Gary's KISS approach. A variac feeding a suitable transformer and a decent meter. Just about bullet proof and dead easy to use. Just remember to leave the variac turned down to zero when not in use and check again before switching it on. I understand you can get cheap DVM modules which are ideal for the meter. I've not used them but I'm sure those who have will give relevant advice.
If the maximum heater voltage you'll need is 6.3V then use a 6.3V transformer, or something not much more than that. If you need much more than that consider something with taps. Dual 6V secondaries will get you to 12V. You won't need more than that unless you're testing valves designed for series heater chains.
The other occasion this approach won't work is for battery valves which need DC for their filaments. In this case might I suggest - wait for it - a battery
OK, it won't give a strictly accurate voltage but unless you're doing some really critical testing it won't matter.
If the maximum heater voltage you'll need is 6.3V then use a 6.3V transformer, or something not much more than that. If you need much more than that consider something with taps. Dual 6V secondaries will get you to 12V. You won't need more than that unless you're testing valves designed for series heater chains.
The other occasion this approach won't work is for battery valves which need DC for their filaments. In this case might I suggest - wait for it - a battery
OK, it won't give a strictly accurate voltage but unless you're doing some really critical testing it won't matter.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
