开云体育

From: "Mark Davis" <markad7ef@...>
To: "VARA-MODEM" <[email protected]>
Sent: Thursday, July 27, 2023 2:20:12 PM
Subject: Re: [VARA-MODEM] recommendation for HF rig

While this topic started with a discussion of good radios for VARA HF, several posters commented on the advantages of “all band” (HF + 6M + VHF/UHF) rigs, being able to do VARA FM on VHF/UHF bands.

That’s certainly true, but be aware that the built-in USB Sound-Card system on any of the all-band radios is limited to a 3KHz audio bandwidth. Consequently, when using the built-in USB Sound-Card system, the radio can fully support full-throughput for the VARA FM ‘NARROW’ mode, but you won’t see any better throughput if you switch to ‘WIDE’ mode.

Full throughput VARA FM WIDE operation requires approximately 5KHz audio bandwidth, and a flat frequency-response over that range.

If the all-band radio has a mini-DIN6 “DATA” connector, it’s usually possible to achieve full-throughput VARA FM WIDE connection when using a suitable external USB Sound-Card rig-interface device. The Yaesu FT-991A transceiver is a special case in this regard… that radio has slightly different wiring on the mini-DIN6 connector than what is common practice on almost every VHF/UHF transceiver, and almost every other all-band radio.

Mark - AD7EF