Fixing this 100TH

Gluca · 18th February 2007, 04:44 PM

Ciao,

I am running a 100TH at 20mA/915V/-9V loaded by a 180H choke and 0.1uF coupled to a 2:1 interstage tranny (parafeed). Weird thing is that I get -12db@20Hz and -15db@20kHz. Heck?! I used those irons before with no problems. First time here with a 100TH.

Any hint?

Gianluca

dave slagle · 21st February 2007, 01:05 AM

hey gianluca,

i figured this would be worth a bump.

Do you have any rough guesses at what the Rp of the 100TH is at your operating point? I'm guessing it is upwards of 40K which could start to explain your problems.

From the simple model of a choke loaded stage, increasing source impedance (Rp) shrinks bandwidth on both ends due to the finite inductance and fixed parasitic capacitances. Something that gives you 2hz-200khz bandwidth with a 1K source will only net you 20hz to 20Khz with a 10K source.

dave

18th February 2007, 04:44 PM	#1
Gluca tarmac ripper diyAudio Member Join Date: Nov 2004 Location: Back to Italy	Fixing this 100TH Ciao, I am running a 100TH at 20mA/915V/-9V loaded by a 180H choke and 0.1uF coupled to a 2:1 interstage tranny (parafeed). Weird thing is that I get -12db@20Hz and -15db@20kHz. Heck?! I used those irons before with no problems. First time here with a 100TH. Any hint? Gianluca

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Looking for circuit of SE amp. for Eimac 100TH	udonbkk	Tubes / Valves	17	17th August 2011 09:25 AM
Fixing the R30	bjackson	Multi-Way	3	16th May 2010 06:10 AM
Need some help fixing this amp	mazeroth	Solid State	1	13th May 2008 03:04 AM
Need Help Fixing an old NAD 304	li_gangyi	Solid State	14	8th December 2004 07:59 PM
Help! Fixing Amp.	shajan	Solid State	20	29th May 2004 08:06 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

21st February 2007, 01:05 AM	#2
dave slagle diyAudio Member Join Date: Mar 2003 Location: NYC	hey gianluca, i figured this would be worth a bump. Do you have any rough guesses at what the Rp of the 100TH is at your operating point? I'm guessing it is upwards of 40K which could start to explain your problems. From the simple model of a choke loaded stage, increasing source impedance (Rp) shrinks bandwidth on both ends due to the finite inductance and fixed parasitic capacitances. Something that gives you 2hz-200khz bandwidth with a 1K source will only net you 20hz to 20Khz with a 10K source. dave

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)