> In my opinion, the TL922 MUST be modified with a faster relay, or you must > use PTT, or you > must use a large-ish amount of TX Delay to prevent hot-switching.
Another option to deal with sluggish amp T/R relays involves use of an external T/R switch like the Ameritron QSK-5, or Array Solutions QSK Master. Some ops are looking to preserve equipment in its original form, or they're not comfortable with making the mods, or they're timid about working inside an amp. I've been purchasing used QSK-5 units on the used market for under $200, mostly in good electrical condition. That's a bit more expensive than an internal mod to the TL 922 amp, but RF switching is fast, silent and through-loss is reasonably low. I believe a QSK-5PC is also available for installation inside an amp. It may take some minor changes, but the unit should apply well to the TL 922. The key line voltage between the amp and K3 would be more reasonable and a buffer circuit wouldn't be needed. The only remaining issue when using an external T/R switch is that the first keyed element in CW is truncated until the PIN diodes take over after the mechanical frame relay energizes to hold the amp key line low. But, this too can be solved if one want's to make additional bias/switching mods -- which the QSK-5PC likely includes. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
