New Bipolar Boost TX and Front End

[KingJL]

... The primaries were about 4 3/4 turns... My BM4070 measures at 70uH and 80uH... I will live with that variance.

One thing I noted while measuring the inductance. The first core I wound initially tested at 66 uH. The second initially measured 74 uH. As I held the cores in my fingers, the measurements kept increasing to the 75 uH and 84 uH respectively. Tonight i re-measured them, minimizing my handling of them and the measurements were 65 uH and 73 uH respectively. The amount of core temperature effect on the inductance kind of surprised me.

[KingJL]

... Type "J" or T35 may be a better choice?...

Basically, it depends on the core dimensions. For example Amidon FT-50-* would work well with Type J or type 75 (with Amidon, type 75 seems to be same spec as J) as 4 turns would yield ~67uH (which for this application, would be ideal). It has a little greater cross sectional area than the Magnetics ZW-41303-TC. The cross sectional area and mean diameter determine the effective ui of the toroid core. Due to the cross section and mean diameter of the ZW-41303-TC, the initial ui of 10,000 results in an effective ui of 2976. effective ui = ui x Area(mm^2)/Length(mean diameter in mm x pi) .

[Mdtoday]

I'm going to wait and see what JL comes up with his tests. Type "J" or T35 may be a better choice? Mouser also carries the TDK cores.

I like your logic analyser, is that an Agilent?

The logic analyser is a vintage HP1630D with the added 2 analog channels. Cost me more than my car back in 1984 lol.
I have some top end modern gear but this old beast has a sentimental place on my bench and is fired up every now and then.

[Altra]

Thanks for the information Altra, I will check them out.

I'm going to wait and see what JL comes up with his tests. Type "J" or T35 may be a better choice? Mouser also carries the TDK cores.

I like your logic analyser, is that an Agilent?

[Altra]

Great work Altra. Thank you.

Are there ferrite core colors (how ferrite core is painted) of any use in cross reference?

In general no. Maybe some manufactures use color coding? The Chinese use what ever paint color is on the shelf.

[WM6]

See attached ferrite cross reference

Great work Altra. Thank you.

Are there ferrite core colors (how ferrite core is painted) of any use in cross reference?

[Mdtoday]

I found some small 10mm OD Epcos cores on ebay today material type T38 which crosses to Magnetics type "W". Paid $15 for 18 cores. Later found that Digikey carries a full line at reasonable prices. See attached ferrite cross reference


DigiKey T38 toroid cores
https://www.digikey.com/products/en/...=1&pageSize=25

Thanks for the information Altra, I will check them out.

[Altra]

I found some small 10mm OD Epcos cores on ebay today material type T38 which crosses to Magnetics type "W". Paid $15 for 18 cores. Later found that Digikey carries a full line at reasonable prices. See attached ferrite cross reference


DigiKey T38 toroid cores

https://www.digikey.com/products/en/magnetics-transformer-inductor-components/ferrite-cores/936?k=&pkeyword=&sv=0&pv1012=413938&pv70=410068&sf=0&FV=-8%7C936&quantity=&ColumnSort=0&page=1&pageSize=25

[Mdtoday]

I will continue on with measurements using existing cores for now and see If I can get a complete screen shot of logic and output drives

I have setup and tested the outputs for current and last posted (12_3_2019) Vivado project.

Still haven't restored my GPIB software atm so this is just a snapshot of the Aux outputs but looks good.
Timebase = 200us per division





Once I figure out whats going on with the GPIB capture, I'll post some better shots.

[Mdtoday]

When my order for AWG 28 arrives, I will wind the secondaries with 18 turns. That and the changes listed in post #528 (along with returning to 1 ohm in each leg of the primary path) should be ideal.

I will continue on with measurements using existing cores for now and see If I can get a complete screen shot of logic and output drives

[KingJL]

... Just wound 2 with primaries. The primaries were about 4 3/4 turns... My BM4070 measures at 70uH and 80uH... I will live with that variance.

When my order for AWG 28 arrives, I will wind the secondaries with 18 turns. That and the changes listed in post #528 (along with returning to 1 ohm in each leg of the primary path) should be ideal.

[Mdtoday]

How many are you interested in? Ebay is where I got mine. Just wound 2 with primaries. The primaries were about 4 3/4 turns... My BM4070 measures at 70uH and 80uH... I will live with that variance.

Just ordered 25 from Ebay too, will see them in a week or so. The price between 10 and 25 was minimal. Yes, those measurements look good.

[KingJL]

There is an Ebay seller in the US as well, I'll keep searching, something will pop up.

How many are you interested in? Ebay is where I got mine. Just wound 2 with primaries. The primaries were about 4 3/4 turns... My BM4070 measures at 70uH and 80uH... I will live with that variance.

[Mdtoday]

The linked "Magnetics" in post #528 shows an office in Hong Kong... surely there must be a source on that side of the planet!

Unfortunate but no stock in Asia and MOQ from Dexter Magnetics in the USA is 100.
There is an Ebay seller in the US as well, I'll keep searching, something will pop up.

[KingJL]

... Trying to find a local supplier for the ones JL has posted, might have to purchase from the USA by looks of it.

The linked "Magnetics" in post #528 shows an office in Hong Kong... surely there must be a source on that side of the planet!