trinityamps.com

Hi everyone,

It looks like the heater supply voltages are a bit high on my tramp. I'm getting a reading of 7.1 VAC across the wires. Is this an issue and if so, any recommendations for the best way to decrease the voltage to 6.3? I see there's a method here that involves placing two diodes in the heater chain: http://www.valvewizard.co.uk/heater.html

Thanks

What's your mains voltage?
Are all tubes installed?

_________________
http://pdfelectronics.com

Thanks for the quick reply. I retook the following measurements with no tubes installed.

Mains voltage: 121.4 VAC
Voltage across the rectifier pins: 657 VAC
Voltage across the heater wires: 7.1 VAC

A little bit of background info. I have been playing the amp for the past couple days (When I did my first power up I wasn't too concerned about the higher voltages coming out of the transformer secondaries). However, I noticed today that the power tube was glowing pretty bright so I rechecked voltages. With both tubes installed I was reading 7.1 VAC across the heaters as well.

Where are you living? and as kurtlives asked, what is your mains voltage?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Hi there Coco. I live in Ontario and I recorded the mains voltage in my previous post .

Ahh, so I see. 121.4 is a bit hi. The spec is for 117v full load. So that's 4.4/117 or 3.7% high . I don't think I would worry too much. Never seen any repercussions of that.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Good to know.

Just in case, I've attached a picture of the glow on the 6v6 which initially caught my eye and prompted me to recheck the filament voltage. In particular, it's the orange glow at the centre of the tube (the plate I think?) that concerns me. Does this seem a bit abnormal?

looks like the filaments to me.. I was worried about that once before, too.
but it's ok.

Zaphod posted a link to this a while back and I built one works well http://www.geofex.com/Article_Folders/vintvolt/vintvolt.htm

At my house the voltage is usually 123.something. So i picked up a 4 amp hammond trany 6.3 0 6.3 . And instead of a switch I did a split plug and end up with 117. 1 on one plug and 112 on the other.(under load)

Was into it for about $35

and i didn't mean to say 7.1htrs was ok.
If I get to 6.8 or 6.9 I use Aiken urls to reduce the htrs.

that vintage voltage adaptor is pretty cool!

If the mains voltage is slightly high, resulting in a heater voltage that is also proportionately high, then the following may be useful: A pair of ordinary high-current silicon diodes can be added to the heater chain to drop the heater voltage by about 0.7V. I would use 4A diodes. Each one facing the opposite direction to the other. This is suggested in The Valve Wizard's book , which I have and highly recommend.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

SPAM!!