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HT46 SX146 Slave Operation - CW Offset

W0PWE All Messages By This Member #31224 I have the twins connected with the SX146 slave output feeding the HT46 injection port. This works great on SSB but on CW there is no offset so copying the other station at zero beat is a little unpleasant. I could set the BFO for a beat note but then I will be off frequency on SSB.? ? I must be missing something obvious here. I know other Hallicrafters twins can be operated this way so maybe someone has a solution. The HT46 oscillator takes a long time to stabilize and it is a little chirpy. Transceive operation with the SX146 oscillator solves that problem but creates another challenge.
Jeff AC0C All Messages By This Member #31227 开云体育 I typically will put a tick-mark on the BFO at my preferred sidetone frequency but can appreciate how slick an automatic solution would be.? A way to do that in my mind would be to add a vactor diode off that's relay switched with the T/R line.? That would give an adjustable offset on RX.? Not trivial but I'm sure it works.? If there is a FSK line in the TX that may be another way to do it as those FSK circuits are often implemented with a vactor diode.? Sounds like a fun project! 73/jeff/ac0c alpha-charlie-zero-charlie On 11/20/2024 10:52 AM, W0PWE via groups.io wrote: toggle quoted message Show quoted text I have the twins connected with the SX146 slave output feeding the HT46 injection port. This works great on SSB but on CW there is no offset so copying the other station at zero beat is a little unpleasant. I could set the BFO for a beat note but then I will be off frequency on SSB.? ? I must be missing something obvious here. I know other Hallicrafters twins can be operated this way so maybe someone has a solution. The HT46 oscillator takes a long time to stabilize and it is a little chirpy. Transceive operation with the SX146 oscillator solves that problem but creates another challenge.
W0PWE All Messages By This Member #31231 Thanks for your suggestion Jeff. It made me think about this in a little different light and that's good. In the SX146 of course there is no front panel BFO knob. The two beat frequency oscillators 8998.7KHz and 9001.5KHz are set with trimmers inside the receiver and printed next to them it says "critical adjustments do not touch". That is important of course because in slaved operation they need to be set so that you are receiving and transmitting on the same freq.? ? Your varactor idea is a good one. That could be configured as an outboard BFO knob (I wouldn't drill any holes in my precious SX146). A switch (or switch and relay) would take it out of the circuit when in SSB mode. In CW mode I would zero beat the station with the varactor switched out then switch it in and tune the BFO knob for the desired tone. I would just have to remember to have it switched out when operating SSB. Unfortunately the mode switch on the SX146 has CW and one of the SSB selections on the same position. If CW had it's own position on the rotary switch then it could be automatic.? ? Maybe it is easier to just fix the transmitter and forget about slave operation with the RX VFO. The chirp could likely be fixed but the drift is a bear. It takes about 1.5 hours the transmitter frequency to settle down. The receiver however is stable after about 5 minutes.? 73 - Jerry - W0PWE

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