Was ordering a few things from Playthings of the past and saw he had an HVO-6 listed. Figured I'd pick it up to meet the minimum order requirements, since I am a little uncertain about the flyback in my Hallicrafters, and spares are always nice.

The SAMS only has HVO-6 listed as a spare, nothing else.


Got it today and opened it to find the attached... doesn't look right to me. The box certainly says HVO-6 on it, but the writing on the transformer itself is too smudged to make out (Not on the side facing the camera, silly me.. I can make out the "HVO" but not the number that follows)

It's only got three terminals and a filament winding... so I can't use it either way, but I did some googling and found this thread:
http://www.videokarma.org/showthread.php?t=248133&page=7

and mine looks nothing like Bob's. So if what I have is not a 6... what is it?

http://www.videokarma.org/attachment.php?attachmentid=194805&stc=1&d=1496354472

It looks more like merit HVO-8 air core . Something like the RCA 74951 for direct drive circuits. Stancor made one with the number A-8131.

Looking closely, I think you're right. the "6" on the label is faded and could very likely be an 8.

Yep that is a HVO-8 which is equivalent to a Fly 2. A HVO-6 is equivalent to an Fly 3 and were originally a GE replacement. I believe I have a Fly 3 or HVO-6 here if you want to swap me for your HVO-8.

Sounds good, I was contemplating reaching out to Gary at POTP to see if he'd take a return since it was mislabeled and I (mostly) needed to fill out my order for a part I can't get the set running without (focus control).

I'm planning to work on the set this weekend, if all goes well, in a day or two I might actually know whether I need a replacement flyback or not. If I do, swapping is just as good for me, or if I don't need to swap, I'd do it for the price I paid plus postage, should you still be interested. I'll be in touch.

(Interestingly, the Thor column in the Sams does not list FLY-3 as a replacement option, only the HVO-6. Perhaps the 3 wasn't on the market when the SAMS was published?)

(Interestingly, the Thor column in the Sams does not list FLY-3 as a replacement option, only the HVO-6. Perhaps the 3 wasn't on the market when the SAMS was published?)

Also interesting is that your sets OEM part number(55C172/B) is listed in my Thordarson catalog as requiring a FLY 12 as replacement. :scratch2:
I tend to believe Thordarson literature over Sams, but it's possible they both will work in the circuit. Often times it comes down to physical differences in the way they mount.

Well, the manufacturer ought to know what works :) No reason there can't be multiple subs.

For flybacks it also just depends on what taps are available, so long as you have the right combinations of windings for your design any would work.

Maybe someone can cross that RAM number that's currently in your set. It sure looks to be in good condition.

Maybe someone can cross that RAM number that's currently in your set. It sure looks to be in good condition.

Maybe this will help. Bob Anderson posted this on ARF at one time.

http://farm8.staticflickr.com/7232/7182408581_cf72eda594_k.jpg

Yep, definitely looks good. Reason I'm a little hesitant about it is the primary measures about 4 times what the schematic/parts ref states it should.... but I guess if it makes the correct voltage it's not an issue.

The step-up voltage ratio is what your after. The resistance and wire size in the windings determine the current and resonant frequency.

Also interesting is that your sets OEM part number(55C172/B) is listed in my Thordarson catalog as requiring a FLY 12 as replacement. :scratch2:
I tend to believe Thordarson literature over Sams, but it's possible they both will work in the circuit. Often times it comes down to physical differences in the way they mount.

Speaking of problems with part numbers.
I have a new old stock RCA flyback That they swear was used in a 10" table set with a single 1B3 rectifier. Hlowever, this flyback has two filament windings, and, two hv rectifier connections. Also, the single flyback is shown to put out maximum Ten kv.
Ne flyback gives a total of 13-15 kv.
Bill Cahill

Bill,

The double windings are a dead give-away that it was really intended for a larger CRT set. Otherwise the frame and core look identical. We recently discovered this while looking up fly numbers for another member, but I can't find the other post right now.

Well, thank you very much.. If you find it, I surely would be interested.
Bill Cahill

Bill,

In case you're still wondering... I've found some more information about the two earliest RCA flys that share the same frame/core. RCA numbers 211T1, 211T3 look like the standard FLY 1 we're most familiar with for sets with 10BP4, 12LP4. RCA part #211T5 appears to use the same core and frame but was intended for early sets using a 16AP4. I believe the dual rectifier version to be the equivalent to a Thordarson Fly 4. Has anyone a Fly 4 in their possession that can verify? They would appear to be a very rare item. I believe the below picture is a dual rectifier version which would be for the larger CRT. Bill, does that flyback you were referring to earlier have any identification number on the frame or box?

http://videokarma.org/attachment.php?attachmentid=197762&d=1538606550

HINT
When you have to ID something thats faded scan it & work with
the various tools to enhance it.
Works great with stamps. Also have done it with dug colonial coppers
with some success.

73 Zeno:smoke:
LFOD !

No on the frame, and, it's a replacement Thordarson. Number on flyback matches number on box, but, from there, disagreement. I goofed. It if for two rectifiers. But, replacement numbers listed are for the 10" rca's. The schematic fro the tv in the red book lists a third number.

No on the frame, and, it's a replacement Thordarson. Number on flyback matches number on box, but, from there, disagreement. I goofed. It if for two rectifiers. But, replacement numbers listed are for the 10" rca's. The schematic fro the tv in the red book lists a third number.

Well what are the matching numbers on the flyback and box? It's hard to help solve the mystery if you're going to be so secretive. :D