|
Title: DX-60 Microphone Post by: KB3WYZ on May 12, 2015, 11:43:16 AM Hi Guys, A few weeks ago I got an Astatic DN-HZ microphone, it has the button type plug.
It measures 973 ohms DC. I hooked the mike up to the DX-60 and turned the xmtr. to AM then holding down the CW key transmitted into a dummy load antenna. Didn't hear anything from the receiver. Does this mike have to low of impeadance? I was thinking of building an amplifier using an LM 741 opamp and a LM 386 audio amp. like this. http://makezine.com/magazine/make-39/electronics-fun-fundamentals-the-eclectic-electret-microphone/ Think this would work? Thanks for any ideas Gary Title: Re: DX-60 Microphone Post by: DMOD on May 12, 2015, 12:01:15 PM Hi Guys, A few weeks ago I got an Astatic DN-HZ microphone, it has the button type plug. It measures 973 ohms DC. I hooked the mike up to the DX-60 and turned the xmtr. to AM then holding down the CW key transmitted into a dummy load antenna. Didn't hear anything from the receiver. Does this mike have to low of impeadance? I was thinking of building an amplifier using an LM 741 opamp and a LM 386 audio amp. like this. http://makezine.com/magazine/make-39/electronics-fun-fundamentals-the-eclectic-electret-microphone/ Think this would work? Thanks for any ideas Gary The DN-HZ is supposed to be a high output impedance dynamic mike. You were probably measuring the DC resistance of the internal low-to-high impedance transformer, so measure with a high impedance DMM, not a VOM, or you'll frap the transformer. The DX-60 prefers a mike impedance of > 50k ohms. Use a scope and trace the audio from input to modulator cathode. You should not need an amplifier since the mike output should be over 250 mV with a loud "YAYYY." If the speech amp and modulator are working properly the DX-60 should have plenty of voltage gain. Do you have good 12AX7 and a 6DE7 modulator tubes? Phil - AC0OB Title: Re: DX-60 Microphone Post by: N8ETQ on May 12, 2015, 12:08:40 PM Hi Gary I should'nt think you would need to do all that, set the DX-60 up for AM TX and touch the center of the mic plug, you may need to lick your finger but it should respond with buzzes and humms in your RX. Even though the DX-60 has no PTT provisions you may still have to hit the PTT on the mic as it may have been wired for a CB where they use the audio amp for the modulator... If this proves unsuccessful do what Phil suggests. Nice Mic BTW. 73 /Dan Title: Re: DX-60 Microphone Post by: VE3LYX on May 26, 2015, 11:08:19 AM PTT on a DX60 is done with a CW key or connecting then PTT switch to a 1/4 plug and plugging it in where the key goes. Never understood all the fuss over that. It works perfectly and has for several years. Thought everyone did that. What more could you want? AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Secondly the best mic ever in my experience for the DX60 is the Turner hand held that comes with the Lunch box heathkits tener sixer or twoer. For some reason even with out an amp it suits this rig so well I was advised if I ever sold it to make sure that mic went with it. Like all good discoveries it was an accidental discovery. My Cardon Amplified mic farted and I had a twoer sitting there with the right button connector so I stole it to finish a QSO. The difference was dramatic and it is now what I always use. Unfortunately it doesn't have a PTT so I use my key or a foot switch. When the mic died I did the aforementioned "lick and touch test" mentioned in the previous post and knew immediately the radio was fine. don |