In my article about the design of an RF RX front-end for the Yaesu FT-221 R, I had promised to revisit the extender I had created for it. In this article, I will provide some further information on that

The eleven plug-in cards of the FT-221r consist of both single-sided and double-sided boards, but in all cases, a double-sided extender with 2 rows of 18 contacts each is suitable to bring all boards outside the transceiver. Essential for enabling measurements, adjustments, and troubleshooting. The extenders I found on eBay were quite pricey, and since boards had to be made for the RF front-end anyway, I decided to include the boards for an extender in the same order. The extender is not only suitable for the FT-221 R but also for the Yaesu FT-225 D, the FT-301 D, and FT-625 D/RD, and likely many devices from other brands. First, some background on the connector itself. This series of print edge connectors is defined in military specification MIL-C-21097 but often referred to as the 305 or 805 (world-) industry standard. They have a pitch of 0.156" (3.96 mm) and can be ordered from suppliers like Mouser and Digikey (EDAC 305-036-500-208). However, the price is quite high: around €15 each. On AliExpress, they are easily found as "805 strip connector 3.96mm 2 x 18 36p Type-B" (Type B has solder tabs, type A has pins for mounting on a backplane and is therefore less suitable). At AliExpress, you pay less than four euros for three pieces, and they are of good quality!

The schematic of the board is not worth mentioning: a connector that is one-to-one connected with a corresponding footprint on the other side. In the appendix of this article, there are some images, dimensions, and also Gerber files available for those who want to have them manufactured by one of the well-known PCB production companies.

Because the minimum order quantity at JLCPCB - where I had the boards made myself - was 5 pieces, I have some extras left. Unfortunately, I have fewer connectors, but if there is sufficient interest and patience, I am willing to see if I can include them in a future order.