And now for something completely different...

[W7TFO]

Which is the better mid-level triode?

The V-70D  (aka UX/CV11 United)

The HF-100 Amperex

Learned opinions only, please no hijacks to tubes with handles or fins.  830B entrants accepted as well.

73DG

[flintstone mop]

The Amperex looks more like an 810...Are you building something for the HF bands?
Prolly a couple of the HF100's would get legal limit. Seems like same specks as an 810.

[KM1H]

Look at the old handbooks and other amp articles that specifically included those tubes as options. The various HF's, V-70D, 5514, and others were all pushed at times by authors pimping their employers latest and greatest.

Ive always used the 100TH/TL, HK-254/354, 8000 and 810 as the starting point for comparisons and subs at those power levels.

Carl

[W7TFO]

These were sort of an anomaly, in that they both used the small 4-pin UX base, rather than the jumbo like the 211 or 810.  Also the envelope size is smaller.

The Amperex HF-200 was almost a direct swap for the 810, along with the United HV-18.  Those were in the 'next' power class up.

I asked as I have laid in a lifetime supply of these and when building starts both types are going back to work.

With the amount of sockets in use for 100 & 250 th's, plus the fact that they ain't making 'em anymore, I've stayed away from collecting them so more of my friends wind up with good ones.

If anyone needs obscure transmitting tube data, there are data sheets here I have compiled for over 50 years and will gladly forward info via E-mail if I have it.

Many thanks,

73DG

[KE5YTV]

Us Globe King owners try to hoover up all of the V70D's. 

Mike

[W7TFO]

The UX/CV-11 is a socket compatible sub for the V70-D.  A bit lower mu, 10V fil rather than 7-1/2V.  Not too hard to make it go.

Those CV-11's were widely used in diathermy applications, and show up NOS more often than V70's.

73DG

[KM1H]

My first ever amp was around a pair of HF-250's from a diathermy. Never did get it to work well, they were probably worn out.

Picked up lots of BC-610 and other stuff from AFMARS and went with 250TH's and 810's for audio. A big difference with brandy new bottles.

[W7TFO]

New, or more appropriate today, unused old tubes are indeed wonderful to work with. 

I am amazed at how long a good, hard vacuum can last in a lot of them. 

More good tubes are killed by idiots that haven't a clue how to pack & ship tubes.

Ones with emission a bit off are usable for prototype design in case something (usually) goes wrong early on.

73DG

[KM1H]

At the 600-800W output level Id be more inclined to go with a pair of 813's. The 300V screen supply is nothing critical and a pi net makes life so much easier for those of us who prefer coax.
Even my triode amps are pi-net and a lot easier to neutralize.

Carl

[Bill, KD0HG]

Think about having spares of whatever you
plan to use. 810s are wunnerful bottles.