microphones


Michael Danese
 

I ordered a uBITX V6 transceiver (full kit) a couple of days ago, and am looking forward to receiving, building and using it. I'm a sucker for QRP. Back in the early 70's when I got my General Ticket, I built my QRP transmitters from scratch, or modified surplus equipment.

 

Got out of HAM Radio in 82 (when the company transferred me) but kept renewing my ticket, and just got back in.

 

I intend to put up a better antenna. Right now I am using an end fed (with balun) long wire, but the antenna is right out my radio shack window, and the RF is leaking into my cheep condenser mic on my current HBR4HK (HAMBUILDER) transceiver.

 

Until I get my tower up, I will have to do something to cure my mic problem on both my current rig and the uBITX rig.

 

Is there anyway I can go to a “dynamic” mic on the uBITX transceiver?

 

de WA3WIH


Peter McCracken
 

http://ubitx.net/2018/12/05/dynamic-mic-preamp-runs-off-phantom-power-from-ubitx/

... is one example, but use the search function on the groups.io site as there have been several useful threads on this topic.

HTH!


Michael Danese
 

Thanks for the info Peter.


On Mon, Jul 19, 2021 at 8:10 PM Peter McCracken <peter.mccracken@...> wrote:
http://ubitx.net/2018/12/05/dynamic-mic-preamp-runs-off-phantom-power-from-ubitx/

... is one example, but use the search function on the groups.io site as there have been several useful threads on this topic.

HTH!


Curt
 

Michael

Possibly rf may be getting other places in the ubitx. An antenna to consider is an end fed half wave, they can be well matched across several bands. And perhaps use a little coax to get your rig further away from feedpoint. This may matter much more than microphone type. EFHW can be homebrew rather easily at qrp level, much info on the web. There are also commercial versions such as myantennas.com if you expect to run higher power. 

At least start with the recommended microphone type while you evaluate circuitry for a dynamic Mike. I found an old ht speaker Mike it works well with my v4. 

Glad to discuss antennas further. 

Curt wb8yyy


gareth.paley@...
 

I use a Midland electret microphone ( https://www.amazon.co.uk/Midland-C714-Remote-Microphone-Multichannel/ ) - it has a screened cable unlike cheaper electret fist mikes on Amazon that don't and are susceptible to RF feedback. I've also got a clip-on ferrite ring ( https://www.amazon.co.uk/gp/product/B06ZZP6CGH/ ) at the end of the cable nearest the mic socket. The mic socket is grounded to the chassis with a 22nF cap across the PTT and ground pins on the back of the mic socket. This cured my RF feedback which was pretty horrendous running 300 watts into an end fed half wave 10m from the shack until I applied these remedies. Oh I also have a 1:1 isolator on the coax just before my linear amp.

M0WWS


gareth.paley@...
 

On Wed, Jul 21, 2021 at 08:42 AM, <gareth.paley@...> wrote:
Midland-C714-Remote-Microphone-Multichannel/ 
That first link link should have been https://www.amazon.co.uk//dp/B008JECH5K/


Matt Towe
 

IMHO ….. the problem isn’t the mic, it’s the antenna.
End feds are susceptible to rf problems …. Even more so when random length or not on the half wavelength. I would work on that first.


Michael Danese
 

I believe you are correct Matt. What makes it worse, the end fed is just outside my shack window, only 12 ft up (with the counterpoise wire connected to a ground stake). I put my little frequency counter near my mic when I transmitted, and it lit up like a Christmas tree.

I ordered 100 ft of RG8X, and I'm going to build a 40 meter dipole (with balun), and an off center slope'r for the rest of the bands. The dipole is going to be an inverted V with the apex at the top of a 30 ft tower in back of my house, away from my shack the with the slope'r up about 25 ft.

I believe that will solve the problem, and give me better range with the low power I will have.

Thanks for the suggestion.

Mike WA3WIH


On Mon, Jul 26, 2021 at 5:42 PM Matt Towe <Lizooki@...> wrote:
IMHO ….. the problem isn’t the mic, it’s the antenna.
End feds are susceptible to rf problems …. Even more so when random length or not on the half wavelength. I would work on that first.