\"High-end Audio\"...

[ke...@kjwdesigns.com]

On Friday, 7 October 2022 at 11:47:54 UTC-7, Mike Monett VE3BTI wrote:
....

It should be noted that color TV service (PAL/SECAM) started in Europe
in the 1960\'s, so solid state rectifiers were available.
Great. So how did they handle the filaments and the filament to cathode
voltage? Or did they just go to transformers?

The valves had to be designed with appropriate heat to cathode voltage limits.

Some signal valves such as EF80 only tolerated ~150v (http://www.r-type.org/pdfs/ef80.pdf) so would have to be lower on the heater chain.

Others such as the line-output devices (PL81, PY81 and PL36) could tolerate higher voltages (>200V) and could be higher up.

http://www.r-type.org/pdfs/pl81.pdf
http://www.r-type.org/pdfs/py81.pdf
http://www.r-type.org/pdfs/pl36.pdf

kw

 

[server]

On Fri, 7 Oct 2022 10:56:38 -0700 (PDT), \"ke...@kjwdesigns.com\"
<keith@kjwdesigns.com> wrote:

>I suspect one of the reasons why the US type of transformerless design never took hold is that with only ~5 valves the total heater voltage would be nowhere near 240V and so would require a lot of power being dissipated in the heater dropper resistor.

I once had an AC/DC LW/MW/SW receiver using U-series (100 mA) tubes
(two UCH21, UL21 and UY1N). The filament voltage was 20 + 20 + ´45 +
50 = 135 V. add to this two 18 V dial lamps and the total
voltage drop was 161 V. The resistor only had to dissipate 59 V (6W).

The receiver had been originally used in an apartment building owned
by a tram company, which even in the 1950\'s used 220 Vdc.

 

[Mike Monett VE3BTI]

upsidedown@downunder.com wrote:

I once had an AC/DC LW/MW/SW receiver using U-series (100 mA) tubes
(two UCH21, UL21 and UY1N). The filament voltage was 20 + 20 + ï45 +
50 = 135 V. add to this two 18 V dial lamps and the total
voltage drop was 161 V. The resistor only had to dissipate 59 V (6W).

Nice.

UCH21 X2
Vf 20 Volts / If 0.1 Ampere
Tube UCH21; Triode-Heptode
https://www.radiomuseum.org/tubes/tube_uch21.html
- why two?

UL21 Vf 45 Volts / If 0.1
Tube UL21; Vacuum Power Pentode
https://www.radiomuseum.org/tubes/tube_ul21.html

UY1N Vf 50 Volts / If 0.1
Tube UY1N; Half-Wave Vacuum Rectif
https://www.radiomuseum.org/tubes/tube_uy1n.html

See also List of Mullard–Philips vacuum tubes
https://en.wikipedia.org/wiki/List_of_Mullard%E2%80%93Philips_vacuum_tubes



--
MRM