RE: [Elecraft] SB-221 for K3 need some help.
Hi all, I am from the old school of thinking that sometime I am going to need to key an AC relay in an amplifier and prefer to make a VERY simple interface and generate a set of dry contacts. That way regardless of the keying gender, you are safe. It keeps ground current loops out of the picture too. Mel K6KBE --- On Sun, 8/31/08, Tom Hammond <[EMAIL PROTECTED]> wrote: From: Tom Hammond <[EMAIL PROTECTED]> Subject: RE: [Elecraft] SB-221 for K3 need some help. To: [EMAIL PROTECTED], "'Don Rasmussen'" <[EMAIL PROTECTED]>, elecraft@mailman.qth.net Date: Sunday, August 31, 2008, 10:10 AM Hi Joe & Don: > > I found out this week that K3 is good with Heathkit > > SB-220 amps, all you need to do is connect a shielded > > RCA cable between the units - how easy is that? !!! > >Are you sure? Most of those amplifiers had high voltage PTT >circuits. If I recall correctly the TR relay is a 120V 3PDT >unit. You may need a buffer or soft-key circuit in your >amplifier to make it safe with the K3. The T-R output MOSFET in the K3 is rated at 200VDC at around 5A, so it should not be much of a concern for switching. Additionally, the MOSFET is diode-protected against reverse spikes from the relay it's keying. HOWEVER... this having been said, were it me, I'd add an (internal) Lo-voltage keying interface, like that offered by Harbach, to change the T-R keying voltage presented by the SB-221 from 120VDC to around 2VDC and maybe a couple mA of current. Pretty economical and easy to install, and worth the effort to install. Any T-R keying interface regardless of what you use (OEM or 3rd party) will not, as Joe has pointed out, change the keying speed of the open- frame T-R relay. That is a separate problem which CAN be addressed with replacing the OEM relay with a high-speed power reed relay (drive input) and a vacuum relay (RF output). But you CAN significantly improve the transition speed of the relays IF you NEED the feature. 73, Tom N0SS 73, Tom N0SS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] SB-221 for K3 need some help.
Tom - I have the soft key, but thought I didn't need it after seeing the K3 specs. Why would you depart from that measurement? ;-) The T-R output MOSFET in the K3 is rated at 200VDC at around 5A, so it should not be much of a concern for switching. Additionally, the MOSFET is diode-protected against reverse spikes from the relay it's keying. HOWEVER... this having been said, were it me, I'd add an (internal) Lo-voltage keying interface, like that offered by Harbach, to change the T-R keying voltage presented by the SB-221 from 120VDC to around 2VDC and maybe a couple mA of current. Pretty economical and easy to install, and worth the effort to install. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] SB-221 for K3 need some help.
Hi Joe & Don: > I found out this week that K3 is good with Heathkit > SB-220 amps, all you need to do is connect a shielded > RCA cable between the units - how easy is that? !!! Are you sure? Most of those amplifiers had high voltage PTT circuits. If I recall correctly the TR relay is a 120V 3PDT unit. You may need a buffer or soft-key circuit in your amplifier to make it safe with the K3. The T-R output MOSFET in the K3 is rated at 200VDC at around 5A, so it should not be much of a concern for switching. Additionally, the MOSFET is diode-protected against reverse spikes from the relay it's keying. HOWEVER... this having been said, were it me, I'd add an (internal) Lo-voltage keying interface, like that offered by Harbach, to change the T-R keying voltage presented by the SB-221 from 120VDC to around 2VDC and maybe a couple mA of current. Pretty economical and easy to install, and worth the effort to install. Any T-R keying interface regardless of what you use (OEM or 3rd party) will not, as Joe has pointed out, change the keying speed of the open- frame T-R relay. That is a separate problem which CAN be addressed with replacing the OEM relay with a high-speed power reed relay (drive input) and a vacuum relay (RF output). But you CAN significantly improve the transition speed of the relays IF you NEED the feature. 73, Tom N0SS 73, Tom N0SS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] SB-221 for K3 need some help.
My old SB-220 works just fine with my K3 on CW. Yes, the SB-220's key line is 120 VDC. The kind that will make you let go real quick if you accidentally grab it. The K3 doesn't mind it. The K3's Key Out is rated for +200V at 5 Amps. The stock SB-220 won't do QSK, of course. Set the K3 to semi-breakin with a hold delay long enough to keep the amp keyed between characters, and you're good to go. FB 73, john WA1ABI > > > > > I found out this week that K3 is good with Heathkit > > SB-220 amps, all you need to do is connect a shielded > > RCA cable between the units - how easy is that? !!! > > Are you sure? Most of those amplifiers had high voltage PTT > circuits. If I recall correctly the TR relay is a 120V 3PDT > unit. You may need a buffer or soft-key circuit in your > amplifier to make it safe with the K3. > > Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] SB-221 for K3 need some help.
> I found out this week that K3 is good with Heathkit > SB-220 amps, all you need to do is connect a shielded > RCA cable between the units - how easy is that? !!! Are you sure? Most of those amplifiers had high voltage PTT circuits. If I recall correctly the TR relay is a 120V 3PDT unit. You may need a buffer or soft-key circuit in your amplifier to make it safe with the K3. > If anyone knows where I can get a bandswitch wafer for > the input coil selection I may be able to use this amp > I bought. ;-) At one time Harbach Electronics www.harbachelectronics.com had replacement wafers for the Heath amps. Check with Jeff. He's also a good source of a "soft-key" circuit for the older amps. > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Don Rasmussen > Sent: Sunday, August 31, 2008 1:19 AM > To: elecraft@mailman.qth.net > Subject: [Elecraft] SB-221 for K3 need some help. > > > Hi Guys, > > I found out this week that K3 is good with Heathkit > SB-220 amps, all you need to do is connect a shielded > RCA cable between the units - how easy is that? !!! > > I also found out that UPS had shattered the bandswitch > on the sb221 I recently received and Heathkit is no > longer around to get parts from. hi. > > If anyone knows where I can get a bandswitch wafer for > the input coil selection I may be able to use this amp > I bought. ;-) > > Thanks, > Don > > ___ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] SB-221 for K3 need some help.
Hi Guys, I found out this week that K3 is good with Heathkit SB-220 amps, all you need to do is connect a shielded RCA cable between the units - how easy is that? !!! I also found out that UPS had shattered the bandswitch on the sb221 I recently received and Heathkit is no longer around to get parts from. hi. If anyone knows where I can get a bandswitch wafer for the input coil selection I may be able to use this amp I bought. ;-) Thanks, Don ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
