Re: Topband: Detuning TX ant + QSK
The user's manual I wrote for the YCCC low-band receiving array contains a section on detuning antennas that are near the receiving array. You can download the manual at: https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf. (If the URL wraps because this text gets reformatted, be sure to copy the entire address). See pages 46-48 of the manual. Figure 39 on p. 47 shows a simple circuit that I use with my K3 for simultaneously keying my amplifier (AL-1200 with the QSK-5 option) and the vacuum relays (via a driver transistor) on my TX verticals. The same circuit should work with other radios and amplifiers. I used a simple 1N4001 back EMF diode in this circuit. I'm not sure whether a "faster" diode would be better but this seems to work for me. The most important thing is to prevent hot-switching the vacuum relays by applying RF before the contacts close fully. On my K3, I set the QSK delay to 10 ms and I get excellent QSK operation with this setup. The vacuum relays have held up just fine over 5 or 6 years of operation so I don't think hot-switching has been an issue. 73, John W1FV -Original Message- From: Richard (Rick) Karlquist Sent: Wednesday, November 28, 2018 7:02 AM To: jkaufm...@alum.mit.edu ; 'Jim Thomson' ; 'TopBand List' Subject: Re: Topband: Detuning TX ant + QSK On 11/28/2018 5:18 AM, John Kaufmann wrote: > Jim, > > I use Gigavac GH-1 vacuum relays for detuning my TX antennas when > receiving. The contact closure/release time is 6 msec. You have to dial > in enough QSK delay in your radio so that you don't hot-switch the relays. > > 73, John W1FV > A quick note on the GH-1: 1. In theory, there is no limit to speeding up closure. OTOH, release can only be speeded up to the extent of collapsing the magnetic field by omitting the usual reverse voltage protection diode. After that, the mechanical response remains. 2. This works neatly with the GH-1 being energized on transmit, where you want the quickest response. 3. The limiting factor to speeding up this model is contact bounce. You can only apply a modest amount of speed up before you are limited by contact bounce. With other models, of course, YMMV. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Detuning TX ant + QSK
I have an Ameritron QSK-1 never used and sitting on the shelf that has external outputs for relays. Works QSK with most any AMP $200 or best offer takes it. Herb Schoenbohm On Wed, Nov 28, 2018 at 6:27 AM Jim Thomson wrote: > For you folks that have to de-tune your TX ant, so your dedicated RX > ant works correctly, > if you also operate qsk, how do you do it ? Are you using a sped up vac > relay to de-tune > the TX ant ? I don’t see any other way to accomplish that task. Or do > you use vox cw ? > > Jim VE7RF > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Detuning TX ant + QSK
### another way to speed up the release of a vac relay is to wire a resistor, with a value of aprx 2-3 times that of the vac relay coil resistance, in series with the rvs connected back emf diode. Doesn’t matter which leg of the diode, that the resistor is inserted in. End result is the vac relay will release a lot faster, vs just a back emf diode alone. I use that trick on the input vac relay on my hb amps. Output vac relay gets just the diode. Then the input relay releases 1st, and the output relay releases last. And both are sped up with an overvoltage. + drop resistor. If you are V limited for an overvoltage, you can also wire a small value lytic across the drop resistor. Another method, if you are V limited is to use the 12 vdc version of the GH-1, instead of the 26.5 V version.14-18 vdc + drop resistor will easily speed up the 12 vdc version of the GH-1. Jim VE7RF -Original Message- From: Richard (Rick) Karlquist Sent: Wednesday, November 28, 2018 7:02 AM To: jkaufm...@alum.mit.edu ; 'Jim Thomson' ; 'TopBand List' Subject: Re: Topband: Detuning TX ant + QSK On 11/28/2018 5:18 AM, John Kaufmann wrote: Jim, I use Gigavac GH-1 vacuum relays for detuning my TX antennas when receiving. The contact closure/release time is 6 msec. You have to dial in enough QSK delay in your radio so that you don't hot-switch the relays. 73, John W1FV A quick note on the GH-1: 1. In theory, there is no limit to speeding up closure. OTOH, release can only be speeded up to the extent of collapsing the magnetic field by omitting the usual reverse voltage protection diode. After that, the mechanical response remains. 2. This works neatly with the GH-1 being energized on transmit, where you want the quickest response. 3. The limiting factor to speeding up this model is contact bounce. You can only apply a modest amount of speed up before you are limited by contact bounce. With other models, of course, YMMV. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Detuning TX ant + QSK
On 11/28/2018 5:18 AM, John Kaufmann wrote: Jim, I use Gigavac GH-1 vacuum relays for detuning my TX antennas when receiving. The contact closure/release time is 6 msec. You have to dial in enough QSK delay in your radio so that you don't hot-switch the relays. 73, John W1FV A quick note on the GH-1: 1. In theory, there is no limit to speeding up closure. OTOH, release can only be speeded up to the extent of collapsing the magnetic field by omitting the usual reverse voltage protection diode. After that, the mechanical response remains. 2. This works neatly with the GH-1 being energized on transmit, where you want the quickest response. 3. The limiting factor to speeding up this model is contact bounce. You can only apply a modest amount of speed up before you are limited by contact bounce. With other models, of course, YMMV. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Detuning TX ant + QSK
Jim This will be an issue for me shortly: which part of your tx antenna do you switch for de-tuning? I'm building an inverted L on an FCP and I'm looking for the most convenient place, physically and RF-wise. David G3UNA/G6CP > On 28 November 2018 at 13:18 John Kaufmann mailto:john.kaufm...@verizon.net > wrote: > > > Jim, > > I use Gigavac GH-1 vacuum relays for detuning my TX antennas when > receiving. The contact closure/release time is 6 msec. You have to dial in > enough QSK delay in your radio so that you don't hot-switch the relays. > > 73, John W1FV > > -Original Message- > From: Topband [mailto:topband-boun...@contesting.com > mailto:topband-boun...@contesting.com ] On Behalf Of Jim Thomson > Sent: Wednesday, November 28, 2018 5:26 AM > To: TopBand List > Subject: Topband: Detuning TX ant + QSK > > For you folks that have to de-tune your TX ant, so your dedicated RX ant > works correctly, > if you also operate qsk, how do you do it ? Are you using a sped up vac > relay to de-tune > the TX ant ? I don’t see any other way to accomplish that task. Or do you > use vox cw ? > > Jim VE7RF > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Detuning TX ant + QSK
Jim, I use Gigavac GH-1 vacuum relays for detuning my TX antennas when receiving. The contact closure/release time is 6 msec. You have to dial in enough QSK delay in your radio so that you don't hot-switch the relays. 73, John W1FV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Thomson Sent: Wednesday, November 28, 2018 5:26 AM To: TopBand List Subject: Topband: Detuning TX ant + QSK For you folks that have to de-tune your TX ant, so your dedicated RX ant works correctly, if you also operate qsk, how do you do it ? Are you using a sped up vac relay to de-tune the TX ant ? I don’t see any other way to accomplish that task. Or do you use vox cw ? Jim VE7RF _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Detuning TX ant + QSK
For you folks that have to de-tune your TX ant, so your dedicated RX ant works correctly, if you also operate qsk, how do you do it ? Are you using a sped up vac relay to de-tune the TX ant ? I don’t see any other way to accomplish that task. Or do you use vox cw ? Jim VE7RF _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
