4P1L PSE/PPP module

Like LEGO bricks, I thought about building this module for a pair of loctal sockets for 4P1L. It can be used in PSE or PPP…

4P1L pair ready for testing

4P1L pair module

Turntable cover

As recommended in the Lenco forum, I managed to get a sterling acrylic custom-made cover for my turntable.
I can only recommend this manufacturer as the quality and service are outstanding.

Check their website

Goodbye 4-65a SE, at least for now

After enjoying the 4-65a SE amplifier for many months, I couldn’t resist myself from upgrading the output stage to the 814s. I just needed changing sockets and filament raw supply transformers to fit the requirements of this lovely transmitting valve. Needless to say, my recent tests on 814s were very encouraging. The 814 seemed to perform much better than the 4-65a in delivering 10W of class A2 sound at half the distortion levels. This to me, was only worth trying.

Continue reading “814 SE A2 Amplifier”

6ж52п / 6Z52P in triode mode

I have only one 6ж52п which measures within specs:

Operating point in pentode:

Ia=42.1mA @ Va=150V/Vs=150V
gm=4.47mA/V
Is=4.4mA

Triode curves:

Triode SPICE model:

And resulting SPICE model:

**** 6Z52P TRIODE ******************************************
* Created on 11/17/2013 19:25 using paint_kit.jar Version 2.4 Beta. May 2013 
* Curve traced and model by Ale Moglia 2013 valves@bartola.co.uk
* Curves image file: 6Z52P TRIODE
* Data source link: www.bartola.co.uk/valves 
*----------------------------------------------------------------------------------
.SUBCKT TRIODE_6Z52P 1 2 3 ; Plate Grid Cathode
+ PARAMS: CCG=13.5P CGP=0.5P CCP=2P RGI=2000
+ MU=76.5 KG1=34.7 KP=252 KVB=1272 VCT=-0.11 EX=1.39 
* Vp_MAX=200 Ip_MAX=200 Vg_step=0.5 Vg_start=0 Vg_count=8
* Rp=4000 Vg_ac=55 P_max=11.2 Vg_qui=-48
* X_MIN=64 Y_MIN=48 X_SIZE=421 Y_SIZE=530 FSZ_X=995 FSZ_Y=675 XYGrid=false
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))} 
RE1 7 0 1G ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1} 
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID 
C2 2 1 {CGP} ; GRID=PLATE 
C3 1 3 {CCP} ; CATHODE-PLATE 
D3 5 3 DX ; POSITIVE GRID CURRENT 
R1 2 5 {RGI} ; POSITIVE GRID CURRENT 
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N) 
.ENDS 
*$

814 SE A2 Amplifier (Part 1)

It’s time for the leap of faith. Having tested the 814 in triode mode, I will proceed now to upgrade my 4-65a SE amplifier and replace output valve for the 814. To ensure it can withstand the 540V in the anode, the remaining grids are all tied together through a resistor to the anode. All grids and anode are fitted with ferrite beads as well. A pair of UF4007 in series are placed to protect the Output Transformer in case load is accidentally disconnected.

I added to the UX-5 socket a small bar to place two turrets to provide the anode (top connector), the strapped grid connections through the wire-wound resistor and the pair of UF4007 diodes.

Given that the 814 will run @ 540V / 100mA, I will only need to adjust the Rod Coleman regulators to set current down to 3.25A after replacing the raw filament transformers, as the 814 are 10V instead of 6V filaments of the 4-65a.

Minor DC adjustment will be required on the driver circuit via the gyrator load, so can easily implement this new amplifier.

Stay tuned…

Patti and Lou

Tracing 814 in triode mode

As found years ago during the first traces, the 814 is a sublime companion and remarkably linear. I traced the curves today with the uTracer with great results. From my load lines I could confirm that 10W can be obtained at half distortion compared to the 4-65a.
I will publish results shortly. …
Ale

4-65a Triode Curves

Tracing the transmitter valve curves

I posted several times about my 4-65a SE Amplifier and also traced in the past the curves using my analogue curve tracer to get a view of the loadlines of this fantastic DHT in triode mode.

Now that I have the uTracer I traced again the curves including grid current and A2 anode curves which are very handy for this type of transmitter valve.

My tests were conducted with the following heating and bias setup: