HTX-100 Mic wiring question

[RC286]

I am a newly licenced HAM (as of Oct 30th) VE4BDE.
I have been messing around with radios for a long time, mostly CB, SWL and scanning. I finnaly decided to stop procrastinating and went out and got my licence. Passed basic with honors, so I have access to HF.

Last year at the local amateur radio flea market, I picked up a pair of HTX-100 10m SSB/CW tranceivers for $80. One was suppised to work, while the other was supposed to not TX.After getting my antenna switches and tuner hooked up to my CLR-II (I still use the CB as I am also part of a local SSB dx group on 11m) I tune up the radio with CW, and go to try and make a call on SSB. No RF. After swaping the radios and microphones back and forth, I discover both radios put out RF on CW, but I was getting no power on SSB. I notice with one mic, I am getting very low modulation, and with the other, nothing. Last resort, I pull a mic open, and swap the transducer with one from one of my old CB mics. Lowe and behold, I have power output! So I am sure both radios work, the mics are just shot.

I have a Turner II I would like to wire up to this radio, but looking at the mic wiring, it seems that the PTT and microphone grounds are seperate, at least from the connector to the mic anyway. The turner II being wired for 4 pin, only has 4 wires, and the PTT and mic share the same ground.

Does this radio actually have isolated grounding for the PTT and microphone transducer, or is that just how it is wired from the cassis to the mic.

I ask, because I would like to build a a switchable interface to switch between my turner II 4pin mic and tranformer isolated line in and out (as i read online the mic connector has an audio line out on it) to my PC sound card to have some fun with PSK31 and RTTY.

Has anyone tried wiring a 4pin mic to this radio?

Thanks a bunch

73 VE4BDE

 

[n5sjs]

HTX-100 wiring question

I had a HTX-100 at one time,and when the mic went bad,I used the hand
mic from my Kenwood TS-680S. The TS140 and TS 680S series should
have the same mic pinout. Hope this helps...
73,David

 

[K7MEM]

Actually, inside the stock microphone for the HTX-100, the ground for the PTT and the microphone element are the same. It's not easy to see by looking into the microphone, but is easily seen with the schematic.

Below are links to PDFs of the Manual and the Schematic. The manual does contain a schematic, but the separate one is much higher resolution.

http://www.k7mem.com/manuals/htx_100_Manual.pdf

http://www.k7mem.com/manuals/htx_100_Schematic.pdf

http://www.k7mem.com/manuals/htx-100-service-manual.pdf

Any microphone can be made to work. But you need to determine exactly what is in the Turner microphone you have. Commonly it will be a electret microphone element that requires power. The HTX-100 has a 8 Volt power pin. You need to supply it to the microphone element and at the same time isolate the microphone input on the HTX-100. This is fairly simple to do. Many Turner microphones are also amplified and require power from the microphone socket. I have a Turner +2 that is amplified.

Yes, the HTX-100 microphone connector does have a audio output. I use it myself for PSK-31. I don't use a transformer on either the microphone in or the audio out. It works fine without it.

One word of caution. Do not use the HTX-100 for PSK-31 in the high power (25 Watts) mode. Use the 5 Watt mode. PSK-31 is a continuous mode and may cause the HTX-100 to overheat on long transmissions. The HTX-100 is only rated for intermittent service (SSB and CW).

 

[RC286]

Awesome, I am not sure why I didn't see that in the schematic before. I was probably concentrating on the connector pinout more than the actual wiring of the mic.

As for the Turner II I will have to open it up and see how it is wired internally. It is amplified and powered by a 9v battery.

That is also a good tip about running the transceiver QRP. the thought of it only being rated for intermittent duty didn't even cross my mind. Not a big deal a lot of distance can be covered with digital modes on low power, and I have an amp I can switch on if need be. Looks like I have enough info now to go ahead and start building the interface.

Thanks all,

73, Barrett VE4BDE

 

[K7MEM]

Below is a link to a copy of the PSK-31/CW interface that I use with my HTX-100. The reason some hams use transformer isolation is to eliminate ground loops. I didn't have any audio transformers on hand so I just wired direct. I didn't have any issues, so I left it that way. Even if you do have transformers handy, if you isolate the audio in/out you must also isolate the PTT/CW keying. For that you need to use an opto-isolators.

I have used this interface with DM780 (part of Ham Radio Deluxe) on PSK-31 and CW. There is no Rig Control capability with the HTX-100, so you only need the DM780 part. I have used FlDig, Airlink Express, and a few others without any changes. An interesting piece of software to use for the CW mode is EhoCW. You can connect a set of paddles directly through the Serial Port interface and use it as a keyer.

You can leave the PTT and CW Key connected at the same time because in the SSB mode, the CW Key is disabled internally.

http://www.k7mem.com/manuals/HTX-100_PC_PSK32_CW_Interface.jpg

If you are using a computer without a Serial Port, just get a USB to Serial Port Adapter cable.

If you have a good antenna, the 5 watt mode is all you need on PSK-31. If you try it on CW, you can use the higher power mode. However, don't depend on the software to do perfect copy. Because of all the abbreviations used, Q-Signals, QRM, and QRN, it's often difficult to make sense of what the screen prints out. If you can't copy CW by ear, don't depend on the software to do it for you. But it is fun to see what it can do.

And I almost forgot, you may want to register with QRZ.com. This is because, software like HRD/DM780 has the capability to access the QRZ data base, when you highlight a call sign. US stations are entered in the data base automatically, but all others need to register.

 

[RC286]

Awesome.
Now to go ahead and start digging through my parts bins and see what I have and what I need to buy.
And yeah I plan to isolate the PC from the radio. I have bad luck with computers and noise when I plug them into my radios, so I would rather just eliminate the possibility from the get go instead of trying to fix a problem later on.

Something to do this weekend.

Thanks a bunch.

73, VE4BDE