As luck would have it, here at the office, I happen to have not just a cheap Mega328 tester, but a cheap Chinese 3.5K SE OPT, of the type supplied with these $150 ish 6L6GC amplifier "kits". It has about the heft and dimensions of an XSE-15.
31 Henries and 335 ohms according to the Mega328. If I get some time, I can probably measure the frequency response, but it would be at a low level so maybe not much more useful than this inductance "measurement".
I have tested Hammond 125ESE, Edcor XSE15, and a couple of flavors of Transcendars with my Mega328, and got results about what I expected. I have tested line OPT's with it, and got some real head scratching results.
I have read that some of the cheap Chinese SE OPT's lack an air gap, so it will be interesting to see how the bile fever parts measure out.
Glad to know that Transcendar is winding again. I have been putting off buying OPT's hoping Transcendars would be available again.
31 Henries and 335 ohms according to the Mega328. If I get some time, I can probably measure the frequency response, but it would be at a low level so maybe not much more useful than this inductance "measurement".
I have tested Hammond 125ESE, Edcor XSE15, and a couple of flavors of Transcendars with my Mega328, and got results about what I expected. I have tested line OPT's with it, and got some real head scratching results.
I have read that some of the cheap Chinese SE OPT's lack an air gap, so it will be interesting to see how the bile fever parts measure out.
Glad to know that Transcendar is winding again. I have been putting off buying OPT's hoping Transcendars would be available again.
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Well, I get my annual bonus on Friday and I have made the decision to purchase Transcendar TT-338-OT (10W 5K with UL tap and 4-8-16ohm secondaries). Based on all the discussion in this thread and several others, I can't imagine that this is a decision I will regret.
I will still play with the Chinese ones, and compare them to the Transcendars. Sorry to kilohertz that this is likely too soon for you to piggy-back on the shipping, as you still have some decisions to make.
I will still play with the Chinese ones, and compare them to the Transcendars. Sorry to kilohertz that this is likely too soon for you to piggy-back on the shipping, as you still have some decisions to make.
Some years ago I bought this tester:
DER EE DE-5000 High Accuracy Handheld LCR Meter w/ TL-21 TL-22 TL-23 | eBay
Very consistent and accurate.
Post #32 in the UNSET thread has Hammond 1628SEA VS Edcor CXSE25 frequency response data taken at 10 watts. This is in a new experimental circuit design that I call UNSET....because it works like a Single Ended Triode (SET) amp, but contains NO (UN) triodes.
UNSET is coming?
UNSET is coming?
Yes, same here. I discovered only two weeks ago that Gery was winding again and did not hesistate to put an order in.
(Thats how I ended up buying the Hashimoto's: After I build the 6BQ5 SE I saw a message on his website that he was no longer making stuff. Never thought it might only be temporary.)
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i do not take the reading from these testers seriously, why? because no dc currents were used, i believe the real inductance will read a lot lower with dc impressed on the windings..
these cheap china testers have another use, that is to check for adjacent turns shorts on transformers and chokes...
any good winding on a choke or a traffo will register both inductance and resistance values, a bad one will only show resistance that is way lower than a good one...
Thank you. I have one, too, but I always take it's reading for inductors with a "grain of salt" per se. The one I bought (T4?) states (paraphrasing) it's rubbish for BIG inductors like 10+ Henrys... Still, It does give a reading
When I test the primary inductance of a series feed transformer, I use a handheld LCR meter with some big bipolar electrolytic caps between the probes and the primary winding of the output transformer. At the same time, I setup my bench DC supply and an IXYS chip as an adjustable current source to send some current through the primary winding.
From my experience, some transformers give an inductance rating with no standing DC current, which I don't like, some are dead nuts on at their given operating current (for example any Triad/Hammond choke is usually bang on), and some are hopelessly far off no matter what I do.
From my experience, some transformers give an inductance rating with no standing DC current, which I don't like, some are dead nuts on at their given operating current (for example any Triad/Hammond choke is usually bang on), and some are hopelessly far off no matter what I do.
agreed, but to have a number that we know would become low with dc in the coils is better than not knowing at all....
Thanks Cogitech,
Well they may well be just the ticket for your main system....after all they have features such as this.
"Designed with the latest bile fever concept"
"output cow is not afraid of cumbersome"
And of course the disclaimer.
"Please allow minor deviation due to manual measurement."
Gotta love the translation tools.
They certainly meet my original criteria so I hope they are good sounding units. Looking forward to hearing about them when they arrive, and I will have to pay you a visit when you get the amp done. I think I will hold off for now, still trying to decide which tubes for my first SET build.
Cheers
It's the "anaerobic Copper enameled wire" I'm after!
I think the translation should be "oxygen free copper, coated wire".
I'm happy to report that the Chinese Cheepies have arrived.
- They have a U/L tap (nice surprise!)
- They weigh 996g and 991g respectively (~2.2 lbs)
- Primary resistance is 370ohms (both the same)
- Secondary resistance between 0 and 8ohm is 1.8ohms (both the same)
- I have no way to test inductance but the claim is 25Hy, which seems entirely appropriate for this size of OPT
- I'm calling it a 6 watt OPT
Note: they are the same size, despite the perspective distortion in the photo:
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Size of the transformer depends a lot on what steel has been used - if modern steels are used then the transformer can end up half the weight of what they were in "the good old days". This is where a lot of trust in the manufacturer comes in - I've known "output transformers" in Chinese amplifier to consist of recycled mains transformer steel.
In the translations of Chinese into English they may also have skipped that a transformer is either for HiFi or for guitar use - the latter can be a lot smaller.
What of more concern to me is the measured output resistance - if that resistance value is correct then around 20% is being lost there (1.8 Ohm in transformer with an 8 Ohm load).
I have an old moving coil meter especially for mesasuring those low ohms as I found that often the modern digital meters do not give a good result.
In the translations of Chinese into English they may also have skipped that a transformer is either for HiFi or for guitar use - the latter can be a lot smaller.
What of more concern to me is the measured output resistance - if that resistance value is correct then around 20% is being lost there (1.8 Ohm in transformer with an 8 Ohm load).
I have an old moving coil meter especially for mesasuring those low ohms as I found that often the modern digital meters do not give a good result.
Transcendar sells 7 watt OPTs that are about this size/weight, and by all accounts they are great OPTs.
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