Re: DSB transceiver for Digital mode

Adam Rong
 

Ron,

Thanks for the questions.

1. The PCB size is around 100x64.
2. The heating resistor is recommended for 14MHz. It is really a balance between short term and long term but I see overall improvement. This idea is very rare so I need some more experimentation from you guys.
3. The real concern is not sensitivity but SNR. Since the output impedance is several hundred ohms, by using one transistor, the signal is big enough to give 40-50dB, already bigger than recommend 30dB. My previous version was LM386 and I don’t see much difference. However I have to say that the receiver SNR report  is noticeably worse than big radios. I can easily improve receiver itself but considering transceiver overall, I have to sacrifice a bit. The receiver performance is reasonable to match one-watt DSB transmission. You have to balance.

Thanks,
Adam

在 2019年5月6日,上午6:24,Ron Stone <rsstone2@...> 写道:

Adam,

Glad to hear about your progress.  Just a few questions.

- What are the dimensions of the PCB (or case)?

- Do you recommend using the heating resistor especially on the 20 meter version?  Was the stability still ok without it?  How much did stability improve with the resistor?

-  Did you experiment using a higher gain LM386 or other audio amp instead of the single transistor audio amp circuit that you're using?  If you did, was there much difference in performance?

Thanks again for all your efforts!

73,

Ron (KA3J)

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