Needed - Advice on tubelab Simple SE build

[Salsero]

I am building a simple SE using KT88 tubes with a choke supply - a few questions follow:
1. What value should I use for the R17 and R27 resistors?
2. I am going to use a socket with a filter and fuse - what AC line power rating should I specify?
3. There are several switches used for the amp - the ultralinear and cathode feedback switch. Any recommendations on which switches to select?

Thanks all
Salsero

[boywonder]

Originally Posted by Salsero

I am building a simple SE using KT88 tubes with a choke supply - a few questions follow:
1. What value should I use for the R17 and R27 resistors?
2. I am going to use a socket with a filter and fuse - what AC line power rating should I specify?
3. There are several switches used for the amp - the ultralinear and cathode feedback switch. Any recommendations on which switches to select?

Thanks all
Salsero

See this page from Tubelab's site:

Tubes & Transformers

Study the simulation tables near the bottom of the page.

The output tube cathode resistors (Rk) depend on what output tubes (in your case KT88's) and output transformer primary impedance (load Z) you intend to use, as well as your B+ voltage. The table lists data for 3K and 5K transformers and various B+ voltages. Note that as you lower Rk or increase B+, more current flows through the output tubes, increasing max plate dissipation (listed in watts as power) and power output. The values in red indicate that they exceed the max power dissipation ratings of the typical KT88, although some folks run their amps at these levels comfortably. You may want to try various cathode R values (Rk) once you have built the amp. Some builders here have incorporated switchable Rk values for on-the-fly changes or running different output tubes. If you are using a choke input power supply, you can easily vary your B+ voltage by changing the value of C1 within a small range.

I am unclear as to what you are asking in your "power line rating" question...
If you are specifying the fuse value, use a 1 amp slo-blo.

[JdJ]

The UL and Feedback switches need to be DPDT. The rectifier switch (if you are using it) only has to be a SPDT. I ended up using the ubiquitous Mountain toggle switches available through Mouser and (I think) Digikey. If I'm not mistaken they are rated for 3 amps at 125v. For power I used:

103-0132-EVX from Mouser

Best of luck,

Josh