Fluorescent ballasts in SE

[Jaime]

The Australian magazine Siliconchip has published an amplifier SE using tubes 6L6.

<<< To overcome this, we have used an output configuration that has become known as "parafeed". This uses a relatively low-cost high impedance choke as the load for the plates of the output valves and a capacitor couples the audio signal to the primary of the output transformer. As a result, there is zero DC in the primary winding, so the output transformer can be much smaller and lower in cost without sacrificing quality.>>>

<<< The plate current for the two valves passes through a 9H (nine Henry) choke – essentially three standard compact fluorescent ballasts connected in series – and this provides a high AC impedance but low DC resistance to supply the HT to the plates. >>>

http://www.siliconchip.com.au/cms/A_...2/article.html
http://www.siliconchip.com.au/cms/A_...2/article.html


The choque is 3 standard compact fluorescent ballasts connected in series?????
Somebody has used this?

best regard
Jaime

[Giaime]

Hello Jaime! What a beautiful name

I've tried. Their inductance is pretty low (don't expect 3H from each of them, 1 seems more realistic), but the problem is that they aren't gapped so even with small DC currents they saturate and the inductance goes down.

I can't see the problem, chokes are pretty cheap, cheaper than neon ballasts (not if you already have them).

My transformers source has 10H 100mA chokes for 16euro each.