noisey pic in Roundie philco

[old_coot88]

Originally Posted by DaveWM

I tried bridging another VDR and was able to adj the bias to get it down to about 200ma with normal scenes, but then the HV was around 19 and the horz sweep was falling short about 1/4 inch on both sides.

Dave, in cases of borderline width and you've exhausted all avenues, there is a little trick that often helps. If you happen to have some 6KV rated disc ceramic caps of around 68pf, 82pf and 120pf, what you do is take the smallest one first (the 68pf) and put it directly across the damper, cathode to plate. This will kick the width out a quarter inch or so on both sides. If it's not enough, sub the 82pf, and if still not enough, try the 120pf.
Each stage will also drop the HOT current by 5 milliamps or so, which you can compensate for with the bias or by upping the screen grid voltage.
You can only take this mod so far, because each stage also drops the HV a bit (as in the old saying "there is no free lunch"). But there is usually a compromise where you have adequate width with reasonable HOT current and decent HV regulation. This situation also often crops up in Admirals using the 6KD6.
Bill(oc)