I bought 2 kits in the same order with both boards labeled V1.1, but the schematics both say V1.0 dated February 24, 2014. ?Both schematics specify detail for L3 and L4 in Chinese, but on the Internet I found a version in English. ?That version says L3 is an FT37-43 black toroid with 11 turns. ?L4 is a red T37-2 with 16 turns. ?Both kits supplied one red toroid and one green toroid. ?Winding 9 turns on a green core, I read 555 uH, so I rejected it! ?I happen to own a?batch?of?FT37-43s, so I substituted those for the green cores. ? I wound L3 with 11 turns to get about 36 uH. ?On the V3 schematic for the Frog Sounds 49er the inductor on the D882 collector was marked 22uH, so I removed turns to get to about 24 uH. ?With L3=24 uH and L4=1 uH, the receivers work in both 49ers, but not well. ?

The mIni Ring Core Calculator from DL5SWB says 11 turns on a red T37-2 should measure 484 nH and a red T50-2 would show about 1 uH. ?When I tested the supplied red core with 15 turns, I read about 1 uH on my L/C Meter IIB, so I am guessing it is really a T50-2, not a T37-2.

Neither transmitter works. ?Attempting to fix one, I first replaced the Q5 D882 with a BD139, but still no joy. ?Then I replaced Q6 and yet again, no deflection of the wattmeter. ?The boards are too small and lumpy to make good frisbees.

While I was mulling this mess over, I assembled a Frog Sounds 49er. ?Both receiver and transmitter tested fine in Froggy. ?Froggy transmitted nicely to a V1.1 49er and to a ham a couple of miles away. ?It appears to me that the antenna filters in both 49er versions are identical so that the L5 1 uH in Froggy should be the same value for L4 in the other version

So, my question is, does anyone know definitively what values I should use for L3 and L4? ?I have T50-2's and FT37-43s.

Thanks for any help whatsoever.

Bob KF6ABC Mix

Bob:

??? I checked the schematic and the L3 inductor which is a FT37-43 has 11 turns, and L4 which is a T37-2 gets 16 turns.? In my 49er kits, the L3 inductor is Green and the L4 inductor is Red. The FT37-43 is a?somewhat? larger core than the FT-37-2.

???? This combination seemed to work well with my 49ers.

72,

Marc N4DR

????

Bob:

? One mistake which I made, is very easy to do. When building the 49er for this project it is important not to forget the jumper on the bottom of the board between the pin of C10 which is closest to the NE602 and the empty hole for C5 which is also closest to the NE602. Without this jumper, the receiver will work fine, but the transmitter cannot get any output from the DDS board, and is going to be dead. In addition, I would strongly recommend replacing Q6 with a 2N3904 NPN. It runs cooler and is less likely to blow out. Also a heat sink with heat sink grease on the 882 is a good idea to prevent failure of the device during long transmissions.

?? Best of Luck!

Marc N4DR

开云体育

Thanks a lot, Marc.? Knowing the supplied parts worked for you motivates me to replace my L3 first, then I will replace Q6.

Bob