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-   -   GB for F5T Convertible amplifier boards (http://www.diyaudio.com/forums/group-buys/211776-gb-f5t-convertible-amplifier-boards.html)

Tea-Bag 29th April 2012 04:02 PM

GB for F5T Convertible amplifier boards
 
4 Attachment(s)
Presenting the F5TCovertible board.


The soul of this board arose from being unable to locate reliable and long term sources for the FQA Fairchilds for the F5Turbo, so selflessly given to the greedy boyz via Papa.

So based on previously seeing efforts such as Juma's Toshiba based F5 and BkSabath's F5 that uses TO-220 outputs, I realized that we are overlooking some possibilities here.

The FQP variants (FQP19N20C and FQP12P20) are still available via distribution, are not obsolete and not too expensive. Except for some temperature limitations, these devices are meant to be identical. In any case the dies inside the FETS are real small anyways, so what this comes down to is dissipating heat to the heatsinks as best as possible.

To those less interested in pursuing TO-220 it is also can take standard TO-3P or TO-247 devices as you can see.

The hole alignment for the FETs is 40mm. The whole alignment for the Diodes is 20mm from center of the FET. So this is not quite compatible with the DIYAUDIO UMS standards, but does take them into account. If your not using diodes, then it is compatible. If you use your Diodes off standard heatsink,and on to smaller style heatsinks, it's still compatible.

The board is deemed Convertible since you can use different FETs, and use different versions of the F5 schematic family.

If you want to run a Version 1-2 setup, then one needs to just jumper the center and right pins for the bipolar transistors. This also means you can skip the extra resistors as well. (See pics.)

The final production boards will be white/black legend with Tin pads and 3mm thick (1.6mm is standard) to reduce board flex, and use 2oz copper.

Fair warning - The recommended bias levels voltages may be beyond the normal UMS spacing done here, on a 250MM x 63MM board.
This board will do better fitting into a tighter space with likely less bias. It will still transition into class B fine, but one may want to keep the bias in check or look at the DIYAUDIO Stores solution.

Boards are expensive when big and thick. The pair will run $30.00USD, or 15.00USD per board (order per channel). Shipping will be 7.00 per set. International Priority envelope mail options are available as well for 17.00.

FQP Mosfets will be offered unmatched at current pricing, or matched for extra. Shipping will be custom quoted if interested.

If more than 50 total boards are made, then 1.00 per board will be donated to diyaudio.com.

I want to run a rather short GB timeframe to get the show on the road. The closing date will be Sunday May 13th at 11:59PM EST. So sign up on spreadsheet, follow the Paypal address on spreadsheet.

When submitting PayPal information, please specify your DIYAUDIONAME and parts ordered. Failure to do so, and I will refund your request. Otherwise it's very difficult for me to figure out what you purchased.

a.wayne 29th April 2012 04:16 PM

There is no GBF5T listed on that spread sheet ....

Tea-Bag 29th April 2012 05:14 PM

A.Wayne, I renamed the spreadsheet. Thanks, the link appears to work.
I hope the is what you mean. I am uncertain if I see this differently than you.

Thanks for looking!

Tea-Bag 30th April 2012 11:39 PM

More Pics
 
2 Attachment(s)
Here is a closer Pic of the front end, and back end of board.

Tea-Bag 8th May 2012 03:49 PM

I am going to keep this GB open for another few weeks.

Buzzforb is playing with a set of the boards, everything is working fine, but we are stricking some real world values that may help builders with their decisions.

Tea-Bag 14th May 2012 02:21 PM

I have gone ahead and ordered these boards. I have limited it to 24 total boards.
So this will be a small production run, and we will see if it gains popularity with some use!
So these will be sold on a first come, first serve basis.

Tea-Bag 14th May 2012 11:40 PM

I've had a few late-comers. I can pump the order up in the next few days, so if others are interested, I suggest you pay up today or tomorrow. Otherwise I've gotten assignment for all 24 boards.

T

Nikitas 15th May 2012 10:26 AM

Hi Tea-Bag,

First thanks for the effort!

I would like a set of boards but I would like you to send it to Buzzforb and he will send to me the boards along with the kit.

Can you send a pm to me with the total price and how I should pay and your info?

Tea-Bag 15th May 2012 05:32 PM

Some board sets are going to buzz, then ship to end customers. THat's do-able.

I upped the order to 35 total boards, so I can take several more requests for boards.
I can't do anymore than that so they can spec material size as next step.

So hopefully will have boards in my hands in a few weeks.

Tea-Bag 25th May 2012 11:01 AM

Boards are in!
 
4 Attachment(s)
Here are some of the boards I have now.
They are really thick!

To paid up members who are not shipping to buzz, your boards are going in the mail today.

I have 5 more pairs available. $30.00 a set. Shipping is being uped to 7.00 for 2 brds ( 1 set), and 12.00 for 4 brds.
In USA, 6.00 for up to four is fine.


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