Lundahl Plate chokes, Lundhal Anodendrossel

Manufacturer of Ultra High Quality Audio Transformers
	Introduction (the Part number below, is the same as in the pricelist
Part 1	Tube Power Supply Chokes)	Part14..21	Tube Output transformers
Part 2	Filament Chokes / High Current Chokes	Part 22	Tube Mains transformers with DC cancellation
Part 3	Plate (anode) Chokes	Part 23	Mains Cleaning transformers with DC cancellation
	Grid Choke	Part 24	Transformer Covers (Housings)
Part 5	Interstage	Part 25	Various transformers, not mentioned here
Part 6	Signal Input
Part 7	Signal Output
Part 9	Moving Coil
Part 10	Guitar Input	Tech1	(technical info) PPZ transformers
Part 11	Microphone	Tech2	(technical info) Product Storage
Part 12	For Digital Audio. Finest Quality	Tech3	(technical info) Amorph Cores
Part 13	Interconnect Solutions	Tech4	(technical info) DATASHEET DOWNLOAD

Grid Chokes

How to connect a grid choke
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Introduction

There are only two such chokes in the program, but actually these are all you need. The 1667-05mA is a universal genius, but it is also large size. If the size is no issue, this is the one to take. However the LL1670 is also a very beautiful piece, since the (grid ) current it can take is 800uA which is really more than you need normally.

Some things to know about grid chokes:

Grid current is a small DC current, coming out of the grid. If you have 1uA and a grid resistor of 2mOhm, that means 2 Volt DC. With a 300B that means 10mA (about 12%) more plate current as you intended.
A good tube has only a few hundred nA grid current only. But how good is a random tube, and why can't you use it any more just because a good working tube has some grid current. The advantage of a grid choke over a grid resistor is the perfect protection of the tube against grid current, coming either out of the tube itself, or it is generated by overdriving the tube. Both ways for getting grid current can happen, and the best protection for expensive tube is a grid choke in that case.
Some also say a grid choke simply sounds better. Here is what causes this: A grid choke increases the input impedance of the tube it is connected to. Input impedance is a several Megaohms or more, with a grid choke. This reduces the distortion of the driving stage significantly.
A not so well known application is the 1:2 step up option with the LL1670. So use it as a auto transformer and as a grid choke at the same time. That gives a noise-free gain of 2x. It reduces the Inductance to 405 Henry, but that is more than you need still.

Datasheet	Signal	Idle current	Henry
LL1667-05mA	Max 390V,RMS.	5mA	810H
LL1670	Grid Choke, for tube Grid. 1:1 or 1:2 step up	0,8mA	540H