The reverse diode across most relay coils is to short out the back EMF from the coil (inductor) when the current suddenly stops flowing. ?Without the diode, there's likely some arcing across the PTT switch.
You're right, my list missed out on the pop fix, though many don't find it all that annoying.
There are two, one that winds up in the headphones, and one that goes out on the air at the start of each transmission.
Here's a thread about the transmit pop, also has a solution to the receive kerchunk: ?
/g/BITX20/topic/5142279I like Raj's addition of a cap to cure the transmit pop, though there is interference with Allard's CW scheme as discussed in the thread.
Here's another thread discussing the problem: ?
/g/BITX20/topic/4105232#22950And another: ?
/g/BITX20/topic/4105485And ?
/g/BITX20/topic/ptt_pop_hack/4460108Do we have a consensus on the best solution for the rx kerchunk yet?
I'd go with Raj's cap for the transmit pop, and if CW is wanted along with the pop fixe then maybe hack the rig to inject CW at the first mixer like the uBitx does.
Jerry, KE7ER
On Mon, Jun 26, 2017 at 08:50 am, KM4TRT wrote:
On Sun, Jun 25, 2017 at 02:27 pm, Jerry Gaffke wrote:
"The grounded end of C130 and D7 should instead be connected to K1-9, so they are across the relay coil."
Hi Jerry, even though I have been following most of this stuff and understand most of it, I have forgotten the reference to the above statement. ?Was this to stop that pause and click when you hit the transmit button? ?If not what is is for, and how do you stop that pause.?
Thanks
Andy
