What are the components Q942 and Q952 for? These were missing from my factory assembled board. The main problem I am having is each time I power up the receive works ok etc, but the second I hit the cw or ptt key the finals blow, drain shows grounded.. Three times in a row now, first time i thought there might have been a shorted wire when mounting board, no and blew a second time, check for shorted land etc. and the land from power in to the finals was burnt into, fixed with small jumper, repalce finals for third time and checked for shorts etc. best i can. made a temp fuse by using a one strand of small copper wire to postive connection and it burnt almost on contact, tried again and the receicer works as before? but also just as before the finals went, saw what i thought was la little some from maybe a bias pot not sure, just pulled the finals again.? Just about to give up on the project but maybe some of you could give me some thoughts , advice , help anything at this point.... :)

chuck

Looking at:

and?
Looks like there is a Falcon 9 going up in the next day.

Nov. 28 Falcon 9 ? Spaceflight SSO-A

Launch time: 1831:47 GMT (1:31:47 p.m. EST; 10:31:47 a.m. PST)

Launch site: SLC-4E, Vandenberg Air Force Base, California

All the best.

?

Dale, be sure your mic input has the 8vDC on the positive audio lead.
QST has another schematic for mic inputs with a separate, third pin
carrying the 8v, which is to connect this pin to the collector of Q1
and insert a small capacitor in series with the positive audio lead to
block DC from appearing on the audio pin. - Rich WB2GXM

On 11/27/18, Dale Brooks KG7SSB <kg7ssb@...> wrote:

Thanks Paul for the schematic of the dynamic mic amplifier stage. I'll give
this a test run and see how she does. Dale

On Mon, Nov 26, 2018 at 10:26 PM Paul Dobosz <pjdobosz@...> wrote:

Here is the schematic ... Assumes phantom power (~8V DC) is on the Mic
Audio line. Can be sky wired and shrink wrapped into a small assembly
with
fly leads that will fit inside of many dynamic mic bodies.

From: [email protected] <[email protected]> On Behalf Of N8DAH
Sent: Tuesday, November 27, 2018 6:43 PM
To: [email protected]
Subject: Re: [BITX20] CW Zero Beat

?

1? left

Dave I got yours set aside and will check with the post in the morning on shipping to the UK
--
David

?N8DAH

If you've got so much clock signal floating around that you have trouble receiving, you might want to find the problem.? My radio is dead quiet with no antenna attached, as is my BITX40.? I can sometimes hear ticks from the rotary encoder without an antenna, but that's it.

What sort of raduino-like-object are you using?
_._,_._,_
------------------------------------------------------------------------

Thanks Paul for the schematic of the dynamic mic amplifier stage. I'll give
this a test run and see how she does. Dale

On Mon, Nov 26, 2018 at 10:26 PM Paul Dobosz <pjdobosz@...> wrote:

Here is the schematic ... Assumes phantom power (~8V DC) is on the Mic
Audio line. Can be sky wired and shrink wrapped into a small assembly
with
fly leads that will fit inside of many dynamic mic bodies.

?

Now that Raduino working, still trying to resolve RX issues.?? There is so much clock signal floating around that it masks the RX signal when I try to trace with scope.? So...

Now trying a brute force approaches to low RF sensitivity and low, distorted audio.? They sort of work...

Audio:
Bypassed board audio amp section and used a LM358 to feed the audio PA IC.? Much improved, but does want to oscillate if gain set too high.

RF:
Built a MMIC front end amp.? I can now hear noise when I connect the antenna!? Signals notably stronger.
Would like to add a RF gain control.? Found that controlling the voltage to the MMIC (thus the current), the gain will change from maximum to a very low value, perhaps even attenuating the signal.

Here is my question:
What are any negative effects of operating the MMIC at currents much lower than specified?
Thanks, Woody? -? KZ4AK