I adopted a similar approach with a couple of Yaesu FL2100 amps I overhauled but built the modern rig compatible TX switching into the amps themselves using the 18vac amplifier transformer winding as a power source via a rectifier and 5v regulator with an opto -isolator switching a BD139 to work the amplifier changeover relay. That presented the rig with +5v at less than 10ma for switch over and of course no external box of tricks just a cable between amp and rig.
Yes, but right now I’m away from home, touring in our motorhome. I’ll post a reply when I get home in a few weeks. There’s really nothing to the SDR protection. It’s just a coaxial relay activated by the transceiver. When the transceiver is put into TX mode the relay disconnects the SDR antenna and grounds the SDR input.
Best explanation on UA-cam not going in circles and struggling for 30 minutes like the few videos on this subject. However, if one of those cheap Chinese relay modules fails in the process of keying, that's the end of your transceiver correct?
No. If a relay module fails then the amplifier won’t key and will be straight through … the transceiver will essentially be connected directly to the antenna via the relays in the amplifier … just the same as if the amplifier is switched off. If the relay module contacts fail short circuit then the amplifier will key continuously …even when the transceiver isn’t keyed. Neither of these scenarios will pose any risk. You won’t damage the transceiver.
What about hot switching the amp? This relay adds several milliseconds delay from the moment the TRX send goes active and the amp switches on. If the TRX is hot at this time, it would mean that the antenna relay of the amp has to switch the full hf power of the amp. Not good... There are several circuits available (and the Harbach soft switch) that switches the amp using a power MOSFET without delay.
That's what the TX delay in radios like the IC-7300 is for. Mine is set to 30 mS which is more than enough to compensate for slow relays. There's no RF from the radio until well after all the relays have switched. It's 'MENU > SET > Function > TX Delay' in the IC-7300.
Hafa Adai Sir thank you for your video, I'm sure you would be the right person to ask about my AL-811 linear, my call is KH2ZZ and wanted to ask you if I'm doing it right, when I tune my amp with the radio, do I look for the "dip" on plate current meter with the lowest reading ? Thank you and hope to hear from you 73 de KH2ZZ
Yes, you normally tune for a dip (low) reading on the plate current meter, then adjust load, then readjust plate. After the first round of tuning it’s usually safe enough to peak the plate adjustment for maximum output. You shouldn’t do the initial tuning at high power. With my FL-2100Z I start with around 10 Watts from the transceiver.
I adopted a similar approach with a couple of Yaesu FL2100 amps I overhauled but built the modern rig compatible TX switching into the amps themselves using the 18vac amplifier transformer winding as a power source via a rectifier and 5v regulator with an opto -isolator switching a BD139 to work the amplifier changeover relay. That presented the rig with +5v at less than 10ma for switch over and of course no external box of tricks just a cable between amp and rig.
Hi there is it possible to do a video showing the SDR system you use to protect the SDR from RF thanks
Yes, but right now I’m away from home, touring in our motorhome. I’ll post a reply when I get home in a few weeks.
There’s really nothing to the SDR protection. It’s just a coaxial relay activated by the transceiver. When the transceiver is put into TX mode the relay disconnects the SDR antenna and grounds the SDR input.
@@VK2AAK Thankyou
great info and explanation!
Thanks so much, just killed a MFJ ARB-704 with a Collins 30L1..this should work great and it less than $6 on Amazon.
Thank you. No nonsense solution.
Best explanation on UA-cam not going in circles and struggling for 30 minutes like the few videos on this subject. However, if one of those cheap Chinese relay modules fails in the process of keying, that's the end of your transceiver correct?
No. If a relay module fails then the amplifier won’t key and will be straight through … the transceiver will essentially be connected directly to the antenna via the relays in the amplifier … just the same as if the amplifier is switched off.
If the relay module contacts fail short circuit then the amplifier will key continuously …even when the transceiver isn’t keyed.
Neither of these scenarios will pose any risk. You won’t damage the transceiver.
@@VK2AAK Much appreciated. This clears up many of my doubts!
What about hot switching the amp? This relay adds several milliseconds delay from the moment the TRX send goes active and the amp switches on. If the TRX is hot at this time, it would mean that the antenna relay of the amp has to switch the full hf power of the amp. Not good... There are several circuits available (and the Harbach soft switch) that switches the amp using a power MOSFET without delay.
That's what the TX delay in radios like the IC-7300 is for. Mine is set to 30 mS which is more than enough to compensate for slow relays. There's no RF from the radio until well after all the relays have switched. It's 'MENU > SET > Function > TX Delay' in the IC-7300.
Very good advice. Thanks Andy. De vk1da
Hafa Adai Sir thank you for your video, I'm sure you would be the right person to ask about my AL-811 linear, my call is KH2ZZ and wanted to ask you if I'm doing it right, when I tune my amp with the radio, do I look for the "dip" on plate current meter with the lowest reading ? Thank you and hope to hear from you 73 de KH2ZZ
Yes, you normally tune for a dip (low) reading on the plate current meter, then adjust load, then readjust plate. After the first round of tuning it’s usually safe enough to peak the plate adjustment for maximum output. You shouldn’t do the initial tuning at high power. With my FL-2100Z I start with around 10 Watts from the transceiver.
@@VK2AAK thank you so much Sir for your input, it would save me some smoke out of my shack 73 de KH2ZZ