Fargen Mighty Plex Power Transformer

[Damiano Righi]

Goodmorning everyone! 
This is my first post ……I ask you for technical help! About 10 days ago I
have purchased a Fargen Mighty Plex amplifier, (awesome!) and I noticed that during gig with the
band, the power transformer tends to heat up a lot! I made some measurements with the thermal
imaging camera (FLIR) and found that after about 1.30h of use with the Master set to 2, the surface
temperature of the transformer rose from about 26 ° C (78.8F) to 54 ° C (130F) degrees,
(environment 25 ° C, 77F).
On the net I found some photos of the Mighty Plex where the power transformer is visibly bigger
than mine: at this point I wrote to Ben Fargen to espose my concern,  but to date I have not yet
received an answer.
I then wrote to Mercury Magnetics, (thanks Patrick!), that quickly and professionally explained to me
somehow not to worry because certain temperature values are "normal", (but I remain worried that
130F degree are really too much and the tendency may be to increase!)
The transformer installed on the Fargen Mighty Plex is a Mercury Magnetics Toneclone PLUS FTDP
DUAL E: B + 310V-0-310V 100mA / 6.3V 5A / 5V 3A (there is an additional output B + 265-0-265V not
used) in cathode biased configuration .
I measured with the TAD Bias meter a current of about 50mA on each of the two Mullard EL34, (new
Apex matched Ip 35mA Tc 6550).
I also did another test with a pair of new matched EL34 Tung Sol tubes with an Ip of 42mA
and the current read with the TAD Bias meter stands at 42 - 45mA: why?
Ok recap…..
Mullard Ip nominal 35mA, measured with 50mA Bias meter
Tung Sol Ip nominal 42mA, measured with 45mA Bias meter
I repeat, why this difference?
If in doubt, I proceeded to connect the transformer primary from 220V to the current 230V, but the result changes little.
Considering that the installed tubes are:
2 * EL34 / 1 * 12AX7 phase splitter (filaments powered 6.3 VAC) +
2 * 12AX7 / 1 * 12AT7 (powered 5 VDC)
I ask you what you think of the sizing of the transformer. Do you think it is enough?
P.S. the cathode resistors are equal to 2 * 430 ohm 5W, each bypassed with 22uF 100V Muse capacitors.
Someone own this amplifier and can take some photos of the transformer installed?
Thanks to those who want to help me. 
Damiano ITALY

[PRR]

Welcome.

130 degrees F after 90 minutes does not seem hot to me. I've had transformers I could not hold which lived for years, decades.

[Damiano Righi]

PRR, mmhhh seems to be ok.... I'm worried about transformer lifespan. What do you think about sizing? Isnt'ir a little small? Could be these a precise amp builder choice?
Maybe, reaches a complete saturation of iron, to obtain a "good" sag and a natural compression results? 

[Damiano Righi]

Here some pictures of Mighty Plex transfomer plus cathode resistor.

[Damiano Righi]

....and some other pictures including thermography and internal guts.

[PRR]

https://www.mercurymagnetics.com/take-your-transformers-temperature-parts-i-ii/