Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

148 GTL CW

C

cdmwaiting4callsign

Member
Apr 21, 2012
15
0
11
I was wondering, if there was any way I could mod my 148 GTL (PC-412 board) so I could xmit some CW on it.
Ive got the extra channel mod on it, and that gives me the very bottom of the 10 meter ham band (where CW is done) and Ive also got my ticket, so Im legal to transmit there.
Ive picked up some CW while in side band around those freqs(well, i can sortof here it in AM mode, but the sideband works kinda like a BFO i guess) and would love to give it a try.
Could it just be as simple as making a mike adapter to connect PTT to a CW key and setting the rig to AM mode? would that work? Also, if it did work, would the constant on and off keying screw up the rig?

Thanks for the info

BTW
I also have a simple frequency counter that I made from a kit off of W8DIZ's site. Its very simple, works with the ATtiny2313 chip, and I can currently use it for testing and xmit frequency, Any Idea how I can hook it up for RX freq display? I realize I may have to make some changes to the firmware, but what points in the radio would I connect it to?
 

The problem wouldn't be transmitting, but receiving. The carrier (dead key) is CW, it just has to be switched on/off fast, you know? Receiving in AM mode would be very difficult, no 'tone' to be heard. That's where that BFO comes in. It'd be easy to hear on SSB, but then there wouldn't be any carrier so no CW. So, if you would be willing to do some modifications to your radio, it would certainly be possible.
- 'Doc

Then again, if you can handle not hearing anything between the dots/dashes, as in not QSK, then just switch between AM keyed carrier and SSB receiving. As in a "sort of" T/R switch??

(That's how it used to be using separate transmitters and receivers back in the dark ages you know. :))
 
I figured i would have to manually switch between AM and SSB to rx anything, I can hear CW signals just fine on SSB.

So there wouldnt be any harm done keying the rig that fast/much? And I could just hook my key up to the ptt switch and start keying away in am mode?
 
Actually: If I remember...you can run CW on 10m in modulated CW (don't remember the mode designation)...However an Electronic keyer hooked into the SSB can be used (or use to be that way)
Am I right Doc?
The club I was in years...ago did that on our 10m link for the local 2m repeater...

Guess you can check the rules now to verify...
All the Best
BJ
 
Ive also got a practice oscillator id like to use while keying , would it be ok to run the 9v from the oscillator across the ptt switch lines from the mic hookup, that is; to key the radio with a key that has 9v running accross it from a battery? Or should I just power the Osc. from the same power supply that the radio uses and use the same ground for the oscillator and the ptt? I think the osc should run okay at 13.8v, its a 555 with 2 caps and a resistor type setup.
 
Last edited:
In general, I don't think I'd apply any voltages across a microphone input as from that practice oscillator. If it had terminals specifically for keying something, yes.
As for that modulated CW, MCW, I don't remember. I'm not sure that can be done in the CW only portion of any band. The 'voice' portions, sure, but not the CW portions. I'd have to look that up too.
- 'Doc
 
as far as i know, MCW is not supposed to be run in the CW portion of the band, from what ive read recently.
One more question:
I have another radio, an elcheapo 1/Beta CB(never even heard of em before) 23 chan w/ crystals, AM only. Im thinking about using this as a transmitter (recrystalled for the 10m band), and the 148 GTL on SSB as a receiver. My question is, how do I hook up the antenna with this setup? Can I use a T connector on the back of the 1/Beta, connect one side to the Antenna (a half wave dipole) and the other side to the 148 GTL? Or is that not good to xmit anything straight into the back of the other radio? If this approach isnt kosher, how do setups with a separate transmitter and receiver work; w/ respect to the antenna.
Thanks!
 
You're right, it isn't a good idea to transmit into another radio. The way it was usually done with separate transmitters/receivers was to use an antenna change-over switch or relay. It's also a fairly good idea to short out the receiver's antenna connections on that switch-over. Reduces the amount of RF getting to that receiver. I haven't seen one of those antenna relays in quite a while, but one shouldn't be that difficult to put together.
- 'Doc
 
keying cw on 148 or other ssb radio....

The easiest way to accomplish cw is to inject a pure tone signal into the mic input on the ssb unit and switch the tone on and off with the transmit circuit keyed continuously. Ideally the injected tone would be something in the 750-800hz range. Injecting the tone is not MCW it gives you true CW. Because the tone should be a clean and constant sign wave, it produces a carrier signal that is + or - the actual displayed (center) frequency. I.E. If you are using USB, you add the tone frequency to the transmitter frequency. Suppose for instance the transitter is set to 28.100mhz an you inject this tone. This would be 28100000hz + 800hz tone on usb = carrier frequency output on 28100800hz (28.1008MHz). To send CW, set the unit to usb, then you simply key the transmit pins with a switch and key the tone oscillator on and off while connected to the input to the mic. This tone injection works very well PROVIDED your transmitter is well aligned, or more specifically, the carrier suppression circuit is properly adjusted. AND the tone is a pure sign wave. If either of these things are off, you could potentially be on two frequencies at the same time. A simple home built oscillator circuit will get it done. I do this with my HTX-10 and run a 10 meter beacon with it. It works well. As a bonus, Mic gain now functions as rf power out and you have the full output power of the ssb mode probably about 12 watts vs 4 watts in the AM (carrier) mode... There are a couple oscillator plans online to do this, I have included a link below...

Using two radios as stated above may work. HOWEVER, if you set the transmitter to AM and key by using the PTT circuit, there is a good chance you will have key clicks and chirping. I can speak of this, because my beacon backup is a cobra 29 cb converted to 10 meters. To eliminate or lessen this chirp/clicking, you would need to short the audio transformer output. This keeps the audio modulation circuits from distorting the signal when switching as the transmitter is switching from transmit to receive (as it does with every character keyed). Remember the winding of the transformer is really an inductor, this is why you need to short it. Mine doens't chirp or click, but my audio transformer is shorted...this would make ssb/am modes useless on your radio. I would inject the tone and leave the radio internals alone--and you only need one radio and no tx/rx switching relays. This information will save both you and the people listening to your signal lots of profanity.

http://www.qsl.net/wj5o/HTX-10.htm
 
Last edited:

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back