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Wow, you must have a rock steady hand to parallel a through hole resistor alongside the SMD resistor. I would not say I have Parkinson disease but my hands are not that steady.

I think I will see if I can find out what the immediate amplifier is after the microphone and the ac component of the audio from the Mic is and see if I can bring about the idea of a pre-amp with gain control. I think the only real problem would be clipping but if you check everything out rather than just stick a guess in it should pan out.

By the way thanks 'all' for the info. I would probably take that route too If I could keep my hands steady.

Mike

On Fri, May 25, 2018, 6:53 PM iz oos <and2oosiz2@...> wrote:

Indeed, I initially thought to add a mic compressor, but reducing the value of R63 by adding a discrete resistor was the simplest thing to do. No smd was removed. It increased, probably doubled the average SSB power so I can more easily drive a small amplifier or whatever.

Il 26/mag/2018 00:14, "Mike aka KC2WVB" <rb5363@...> ha scritto:

Quick question. I think that what your doing is the following: Presumably the audio from the mic's audio line that carries the ac with a dc offset is first passed through a capacitor to block the dc and then used as input into a small preamp, perhaps an op-amp before anything else occurs. If so, then I imagine by changing the value of the named resistor you are increasing the gain associated with the op-amps behavior and consequently the audio's amplification above that of what otherwise occurs.

If my conjecture is near valid I am wondering if there is another way to do this such as by using a little stand alone pre-amp immediately after the microphone and prior to the assumed dc blocking filter. I only wonder because one could then control the gain and I do not have the right stuff for SMD removal or replacement.

On Fri, May 25, 2018, 8:30 AM iz oos <and2oosiz2@...> wrote:

I have changed just R63 so now it is 24 ohm (I added 2 ordinary 100ohms resistors in parallel) as suggested. I confirm it increases the average power to the right level given the stock mic element. Could it be further decreased, let's say 10 ohms?

Il 27/apr/2018 16:26, "Howard Fidel" <sonic1@...> ha scritto:

1K. Change one or the other, not both.

On 4/27/2018 10:14 AM, iz oos wrote:

If R63=24ohm what value should R65 be?

Il 27/apr/2018 16:03, "Skip Davis via Groups.Io" <skipnc9o=[email protected]> ha scritto:

Howard did you also change out R65 that was posted here too.

By the way the parts showed up here yesterday, thanks a lot. Now to find time to install them.

Skip Davis, NC9O?

On Apr 27, 2018, at 09:57, Howard Fidel <sonic1@...> wrote:

Yes. Change R63 to 24 ohms. The earlier rev boards had 100 ohms there, and V3 has 47. I put another 47 ohm resistor in parallel with the one on the board. Now I don't need to yell into the mic.

Howard WB2VXW


On 4/27/2018 3:22 AM, iz oos wrote:

I have checked SSB output for the Ubitx using a Softrock sdr receiver. The carrier is well aligned and the filter gives a very good shape. Whistling is gives full output with the stock mic element. The output seems clean but the average power during normal speech seems to me a bit low. Is there an easy way to increase it? 73, Franco