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QRP transmitter for Boatanchor receivers?
I've searched the web but haven't found the answer to my
QRP CW question. I'm looking for a QRP CW transmitter kit that includes QSK and will mute a boatanchor receiver like an SB-303, SX-101, or 75S-1. I realize that some receivers might not recover fast enough for QSK. I've looked at website ads for Ramsey, Vectronixs, and still don't have an answer. They might do it out of the box; they might do it with a mod but I haven't found the answer. A couple watts of CW and capable of working with the WA6OTP PTO kit. Anyone got something like that working? de ah6gi/4 -- |
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On Wed, 15 Dec 2004 18:43:51 UTC, (Scott Dorsey)
wrote: No Spam No wrote: I want something like a tuna-tin or peanut whistle QRP transmitter but with QSK TR and receiver muting. I'm not saying that the tuna-tin won't work. I don't know if it will or not. The web articles are not explicit on that point. I'd like 1 to 5 watts of clean CW produced by a solid state transmitter. Something that runs on a wall wart would be best. Crystal controlled would be OK but I've been looking at WA6OTP's website. He sells a PTO kit. Some folk have adapted it to various transmitters. I'm not intested in a transceiver. I want it to work with a boatanchor receiver like the .35 uv, 400 Hz, 1 kHz analog readout Heathkit SB-303 or the Collins 75S-1 with a CW mechanical filter and 1 kHz PTO. Don't pass by the transceiver projects. Most of them don't really share anything between the transmitter and receiver sides, so there is no reason you can't just build the transmit section and leave the receive section. The trick is QSK, built in TR switch, and receiver muting. At these power levels, your QSK and TR switching can be done with a single relay. You are not talking kilowatts here. Your key connects to a multipole relay which disconnects the receiver and connects the transmitter to the antenna, keys the transmitter, and supplies a muting signal to the antenna. Any DP3T relay from the junkbox will work. Seems that at least one of the QRP CW transmitter kits would include QSK circuitry to TR and mute a receiver. There is no circuitry needed. It's just a relay for God's sake. --scott Well, I should explain a bit more. I've operated a Tentec Triton IV and own a Signal/One CX7A. The Trition IV is good, the CX7A is almost good enough. I'd like to have QSK not just automatic TR with a relay clacking away. I also have an ICOM IC-720A and it is too slow to be called QSK. Seems that at least one of fun things of CW is QSK. de ah6gi/4 I got a pointer to the 2004 handbook for an add on QSK system. -- |
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On Wed, 15 Dec 2004 18:43:51 UTC, (Scott Dorsey)
wrote: No Spam No wrote: I want something like a tuna-tin or peanut whistle QRP transmitter but with QSK TR and receiver muting. I'm not saying that the tuna-tin won't work. I don't know if it will or not. The web articles are not explicit on that point. I'd like 1 to 5 watts of clean CW produced by a solid state transmitter. Something that runs on a wall wart would be best. Crystal controlled would be OK but I've been looking at WA6OTP's website. He sells a PTO kit. Some folk have adapted it to various transmitters. I'm not intested in a transceiver. I want it to work with a boatanchor receiver like the .35 uv, 400 Hz, 1 kHz analog readout Heathkit SB-303 or the Collins 75S-1 with a CW mechanical filter and 1 kHz PTO. Don't pass by the transceiver projects. Most of them don't really share anything between the transmitter and receiver sides, so there is no reason you can't just build the transmit section and leave the receive section. The trick is QSK, built in TR switch, and receiver muting. At these power levels, your QSK and TR switching can be done with a single relay. You are not talking kilowatts here. Your key connects to a multipole relay which disconnects the receiver and connects the transmitter to the antenna, keys the transmitter, and supplies a muting signal to the antenna. Any DP3T relay from the junkbox will work. Seems that at least one of the QRP CW transmitter kits would include QSK circuitry to TR and mute a receiver. There is no circuitry needed. It's just a relay for God's sake. --scott Well, I should explain a bit more. I've operated a Tentec Triton IV and own a Signal/One CX7A. The Trition IV is good, the CX7A is almost good enough. I'd like to have QSK not just automatic TR with a relay clacking away. I also have an ICOM IC-720A and it is too slow to be called QSK. Seems that at least one of fun things of CW is QSK. de ah6gi/4 I got a pointer to the 2004 handbook for an add on QSK system. -- |
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You really don't need receiver muting for c.w. QSK,
just a receiver who's AGC can be turned off, or is very fast. I ran QSK with a crummy Lafayette HE-80 receiver, a B&W model 380 electronic TR switch, and a Heath Apache transmitter, all sharing a dipole. No keying relays used at all. If I zero-beated a station, I could just monitor my sending with my own receiver. For split frequencies, turn up the volume on the keying monitor. The point of the electronic TR switch is that it acts as a preamp for the receiver, until you transmit. Then, the tube in the TR switch is cut off due to its high value grid leak resistor, which protects the receiver's input stage. The signal is still loud, but if you switch the AGC off, you can hear a breaking station between dits. If your transmitter final is biased off during key up, you won't hear the white noise in the receiver. If your transmitter uses an AB1 or AB2 final for c.w., you may need to increase the final stage bias a bit in c.w. mode, to lower the quiescent plate current. If white noise is still present, you can use a separate antenna for the receiver/TR switch combination. Don't forget to use a coax low pass filter between the electronic TR switch and the antenna, or you will generate TV interference. 73, Ed Knobloch I know that I can buy a Century 21, HW-16, or Argonaut and have just as good a CW QSK experience but I want to use a separate receiver. Seems that at least one of the QRP CW transmitter kits would include QSK circuitry to TR and mute a receiver. de ah6gi/4 I have the receivers, I just need the transmitters. |
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On Thu, 16 Dec 2004 06:27:16 UTC, Edward Knobloch
wrote: You really don't need receiver muting for c.w. QSK, just a receiver who's AGC can be turned off, or is very fast. ... the receiver's input stage. The signal is still loud, but if you switch the AGC off, you can hear a breaking station between dits. Thanks. I'd prefer to something more like Tentec's concept of QSK and not listen to a thumping receiver or hammer my S-meter against the pin. Done right, QSK is a delight. I think it can be done with off-the-shelf pieces. Looks like the key is the www.radioadv.com keyer-TR switch and just about any QRP transmitter kit, or at least that's what folk are telling me. de ah6gi/4 |
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No Spam wrote: On Thu, 16 Dec 2004 06:27:16 UTC, Edward Knobloch wrote: You really don't need receiver muting for c.w. QSK, just a receiver who's AGC can be turned off, or is very fast. .. the receiver's input stage. The signal is still loud, but if you switch the AGC off, you can hear a breaking station between dits. Thanks. I'd prefer to something more like Tentec's concept of QSK and not listen to a thumping receiver or hammer my S-meter against the pin. Done right, QSK is a delight. I think it can be done with off-the-shelf pieces. Looks like the key is the www.radioadv.com keyer-TR switch and just about any QRP transmitter kit, or at least that's what folk are telling me. de ah6gi/4 I fully agree with you that, done right, QSK is a delight. I have been using a Heathkit HR-1680/HX-1681 combination for over 20 years now. The QSK works extremely well. It is virtually imperceptible that the receiver is actually being shut down during my dots and dashes. There is no thumping or bumping or hammering of the S-Meter, and I can hear all of the band activity. IMHO, I think that to have a good QSK setup, you must take the capabilities of both the receiver and transmitter into account. This Heathkit pair was designed to work together. There is a keying circuit inside that controls the timing of the receiver muting, transmitter keying, and T/R switch operation. No relays are involved at all. The low level keying and frequency generation is all solid state and the final (tubes) is run Class AB2, for a nice clean, well shaped, signal. It may be beneficial to get a copy of the HX-1681 transmitter and investigate how they implemented it. I haven't looked at the schematic in a long time but I don't think it was very complicated. It may be similar to Tentec's concept of QSK. I also seem to remember that in the ARRL Handbook, 2000 I think, there was a project for making implementing automatic T/R switching for vintage transmitters and receivers. I don't remember if they went into full QSK, or not, but it's another possible resource. -- Martin E. Meserve - K7MEM http://www.k7mem.com |
#10
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On 16 Dec 2004 12:33:55 GMT, "No Spam " No wrote:
On Thu, 16 Dec 2004 06:27:16 UTC, Edward Knobloch wrote: You really don't need receiver muting for c.w. QSK, just a receiver who's AGC can be turned off, or is very fast. .. the receiver's input stage. The signal is still loud, but if you switch the AGC off, you can hear a breaking station between dits. Thanks. I'd prefer to something more like Tentec's concept of QSK and not listen to a thumping receiver or hammer my S-meter against the pin. Done right, QSK is a delight. I think it can be done with off-the-shelf pieces. Looks like the key is the www.radioadv.com keyer-TR switch and just about any QRP transmitter kit, or at least that's what folk are telling me. de ah6gi/4 I'll admit it's not done very well in the stock Vectronics units. Using the 20m companion receiver, it's more like an AK47 in the headphones! Good thing they don't come with an S-meter! Hey, I paid $19 for a 30m model when TechAmerica had their closeout in Atlanta...minimal expectations. They are good for experimentation. I'm working on a solution for that QSK action, something better than the 1N914 they use. Good luck, Ted KX4OM |
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