[Boatanchors] compairson of 5R4 tubes

[Bill Cromwell]

On Sun, 2012-12-30 at 06:36 -0800, John King wrote:
> I note that there are various 5R4 tubes with different letters after
>  the  5R4, which I suspect refers to the bulb shape, height or other
>  style designations. I am going to order a number of 5R4 tubes for
>  older transmitters such as DX 100s and early Viking transmitters. Is
>  there any difference other than style between the various 5R4 tube
>  versions? Some versions are significantly cheaper than other versions.
>  What are your thoughts regarding the best bang for the buck for these
>  old boatanchor transmitters? Thanks and 73, John, K5PGW


Hi John,

I have been getting the best bang for the buck with solid state
rectifiers, even with any "modifications" that might (or might not) be
required. Modifications could include dropping resistors or all kinds of
other things I've heard about to reduce the higher B+ back to what it
was in the old days. I have just been running my gear with the higher
voltage. I have recapped mine as well and I make sure those filter caps
can take the heat in the kitchen. I have looked to see that other parts
are not subjected to overvoltage. I haven't found any by examining specs
and none by smoke, either. Your precious power supply iron and the
entire radio will run cooler. If you are not going to display them as
"original, rare, cherry, mint, immaculate, collector, museum pieces" you
should consider doing that, too. I have my radios to use. YMMV.

73,

Bill  KU8H