Yup. I had to learn that the hard way. I restored a TO for our club and when I finished with the new caps I plugged it in....on its side. Circuit works, but no keying. The relay must be bad. For the first time I looked closely at the relay and then the light build went off in my head. Turned the unit over and it worked fine.
FYI. Some folks find the sidetone annoying. It's just a sawtooth from a neon bulb relaxation oscillator. So I inserted a series resonant LC circuit directly in series iwth the secondary of T2. I used what I had in the junkbox that provided a decent Q at the chosen note (31mH torroid and 1.33uF worth of parallel mylars). If the network is too lossy the amplitude will be affected and the harmonic attentuation not as effective. This basically translates into chosing a decent inductor that doesn't have a high series resistance. I opted for a tone (750Hz) that was a little lower than what Hallicrafters used so the timing capacitor across the NE2 got padded with 160pF to bring the series LC into resonance (peaking the amplitude in the process). The result was a very pleasing note. The components fit easily under the chassis. Dennis AE6C On 1/2/12, Garey Barrell <k4...@mindspring.com> wrote: > Just don't turn your HA-1 on it's side! > > Mercury relays don't bounce! > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line > and TR-4/C Service Supplement CDs > <www.k4oah.com> > > > Eddy Swynar wrote: >> >> On 2012-01-01, at 7:50 PM, Curt Nixon wrote: >> >>> Just picked up a Hallicrafters TO keyer for the vintage desk also. Same >>> keyer basically. >> >> */Hi Curt,/* >> >> I think that the one major difference betwixt the /EICO/& the >> /Hallicrafters TO/keyer is that very >> same "...weak link" in the chain that affected mine here, i.e. the >> /TO/used (I believe) a sealed >> mercury-wetted keying relay, whereas the /EICO/went with that >> reed-relay-in-a-field-coil route to >> achieve its external keying... >> >> I say weak link as no offence to the /EICO/designers, but rather, as a >> potential source for >> trouble that may well require the owner's attention at some point in its >> future...trouble is, if >> said owner is not all that familiar with the whys & wherefores of reed >> relays / field coils (my >> right hand is raised!), then one can through a /LOT/of vexing gyrations & >> travails in the >> trouble-shooting process that are simply not necessary...! *: >)* >> >> */~73~ de Eddy VE3CUI - VE3XZ/* > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
