Avo CT160 adaptor for B9D - UK Vintage Radio Repair and Restoration Discussion Forum

tomwalter · 24th Apr 2018, 3:05 pm

I'm trying to test some 6JB6s (from a Drake TR4) but my CT160 doesn't have a B9D valve base. I've got a new B9D base and am about to cut up an old EF50 (VR-91) to make up an adaptor for the B9A base in the CT160. I'm anticipating problems with soldering onto the EF50 remnants but I can't find any other valves in my junk to provide a better 'plug'. Has anyone got some better ideas? Regards, Tom

tomwalter · 24th Apr 2018, 9:05 pm

Completely failed as expected! Just been reading David G4EBTs excellent postings on extending valve usage on testers and will follow his ideas. I think I can use the octal base as there is an unused connection on pin 9 of the 6JB6. I'm not anticipating testing other B9D valves.

WME_bill · 24th Apr 2018, 9:52 pm

CT160 adaptors. I'm afraid I decided better to make a hole in the panel, so I fitted a B9D and a B10B bases, taken from old televisions, and wired them in.
For the B10B base, all the valves have one heater to pin 6, so that is always connected, and the other 9 pins can go to the rotary selector panel.
They have gone in very well, and look almost original. Just note that the wiring underneath circles around each holder and follow that. I did put a few ferrite beads on the wires as well.
wme_bill.

David Simpson · 25th Apr 2018, 11:18 am

Tom, you'll find that if you remove the metal skirt from a porcelain B9D - it'll fit snugly inside a Bakelite B9 valvebase. Still leaving enough space inside to fit ferrite beads & secure with plenty of araldite. Likewise with a UX7 into a B7. Something like a thumping great B7A (for QQV06-40's, etc.) would need to be mounted into a wee plastic box, with a B7 connected to it.
I've also fitted a B8B & an IO to an IO plug. All with beads.
Out of all of AVO's testers - the CT160 is more prone to parasitic oscillations when testing high slope o/p valves.
All CT160's have sturdy B7 & B9 valveholders which lend themselves to being used for extensions. I'd avoid drilling/filing or cutting extra holes in VCM's & testers where possible. Metal debris can causes serious problems. Try begging, stealing or borrowing a set of Q-Max cutters, thus keeping drilling to a minimum. Always place lengths of Duct Tape closely under proposed holes - to catch debris on the sticky surface.

Regards, David

MikeViking · 25th Apr 2018, 12:16 pm

Are you unable to source replacement D77 rectifier tubes? I don’t understand why you are hacking into the ct160? Is it for better performance with the alternate tubes?

David G4EBT · 25th Apr 2018, 12:59 pm

Quote:

Originally Posted by tomwalter

Completely failed as expected! Just been reading David G4EBTs excellent postings on extending valve usage on testers and will follow his ideas. I think I can use the octal base as there is an unused connection on pin 9 of the 6JB6. I'm not anticipating testing other B9D valves.

Tom, I've sent you a PM re this.

tomwalter · 25th Apr 2018, 2:56 pm

Very many thanks for all the suggestions. I'm not brave enough to start modifying the CT160 panel - knowing me, it would never work again! I think mating the B9D to an octal base will be the way to go. Very many thanks for the pm David G4EBT. Pm now returned. It hadn't occurred to me to include ferrite beads on the leads. Thanks again all, I'll report back when I have results. Regards, Tom

tomwalter · 3rd Sep 2018, 10:09 am

Just realised I never reported back on the valve base adaptor. Attached is the final result, a new B9D base grafted onto a B9A from an old WD30 valve. Many thanks for the kit of parts from David G4EBT! Beautifully made and works like a dream! All the 6JB6 valves for the Drake TR4C now tested. Thanks again all. Regards, Tom

24th Apr 2018, 3:05 pm	#1
tomwalter Triode Join Date: Oct 2017 Location: Bristol, UK. Posts: 23	Avo CT160 adaptor for B9D I'm trying to test some 6JB6s (from a Drake TR4) but my CT160 doesn't have a B9D valve base. I've got a new B9D base and am about to cut up an old EF50 (VR-91) to make up an adaptor for the B9A base in the CT160. I'm anticipating problems with soldering onto the EF50 remnants but I can't find any other valves in my junk to provide a better 'plug'. Has anyone got some better ideas? Regards, Tom

24th Apr 2018, 9:05 pm	#2
tomwalter Triode Join Date: Oct 2017 Location: Bristol, UK. Posts: 23	Re: Avo CT160 adaptor for B9D Completely failed as expected! Just been reading David G4EBTs excellent postings on extending valve usage on testers and will follow his ideas. I think I can use the octal base as there is an unused connection on pin 9 of the 6JB6. I'm not anticipating testing other B9D valves.

24th Apr 2018, 9:52 pm	#3
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: Avo CT160 adaptor for B9D CT160 adaptors. I'm afraid I decided better to make a hole in the panel, so I fitted a B9D and a B10B bases, taken from old televisions, and wired them in. For the B10B base, all the valves have one heater to pin 6, so that is always connected, and the other 9 pins can go to the rotary selector panel. They have gone in very well, and look almost original. Just note that the wiring underneath circles around each holder and follow that. I did put a few ferrite beads on the wires as well. wme_bill.

25th Apr 2018, 11:18 am	#4
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,853	Re: Avo CT160 adaptor for B9D Tom, you'll find that if you remove the metal skirt from a porcelain B9D - it'll fit snugly inside a Bakelite B9 valvebase. Still leaving enough space inside to fit ferrite beads & secure with plenty of araldite. Likewise with a UX7 into a B7. Something like a thumping great B7A (for QQV06-40's, etc.) would need to be mounted into a wee plastic box, with a B7 connected to it. I've also fitted a B8B & an IO to an IO plug. All with beads. Out of all of AVO's testers - the CT160 is more prone to parasitic oscillations when testing high slope o/p valves. All CT160's have sturdy B7 & B9 valveholders which lend themselves to being used for extensions. I'd avoid drilling/filing or cutting extra holes in VCM's & testers where possible. Metal debris can causes serious problems. Try begging, stealing or borrowing a set of Q-Max cutters, thus keeping drilling to a minimum. Always place lengths of Duct Tape closely under proposed holes - to catch debris on the sticky surface. Regards, David Attached Thumbnails

25th Apr 2018, 12:16 pm	#5
MikeViking Triode Join Date: Feb 2018 Location: Brisbane, Queensland, Australia Posts: 17	Re: Avo CT160 adaptor for B9D Are you unable to source replacement D77 rectifier tubes? I don’t understand why you are hacking into the ct160? Is it for better performance with the alternate tubes?

25th Apr 2018, 2:56 pm	#7
tomwalter Triode Join Date: Oct 2017 Location: Bristol, UK. Posts: 23	Re: Avo CT160 adaptor for B9D Very many thanks for all the suggestions. I'm not brave enough to start modifying the CT160 panel - knowing me, it would never work again! I think mating the B9D to an octal base will be the way to go. Very many thanks for the pm David G4EBT. Pm now returned. It hadn't occurred to me to include ferrite beads on the leads. Thanks again all, I'll report back when I have results. Regards, Tom

3rd Sep 2018, 10:09 am	#8
tomwalter Triode Join Date: Oct 2017 Location: Bristol, UK. Posts: 23	Re: Avo CT160 adaptor for B9D Just realised I never reported back on the valve base adaptor. Attached is the final result, a new B9D base grafted onto a B9A from an old WD30 valve. Many thanks for the kit of parts from David G4EBT! Beautifully made and works like a dream! All the 6JB6 valves for the Drake TR4C now tested. Thanks again all. Regards, Tom Attached Thumbnails