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Reviews Categories | Packet TNCs | MFJ-1278 Help

Reviews Summary for MFJ-1278
MFJ-1278 Reviews: 2 Average rating: 3.5/5 MSRP: $395
Description: The MFJ-1278 is a multi-mode Terminal Node Controller with HF and VHF packet capability. It also resolves CW and Baudot and ASCII RTTY.
Product is in production.
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K9OJ Rating: 4/5 Jan 16, 2015 06:39 Send this review to a friend
New Life as TNC-2 Clone  Time owned: more than 12 months
I bought my MFJ-1278 back in 1987 and over the years upgraded it with the DSP and 9600 baud G3RUH modem daughter cards. The 1278 has KISS mode built in but I was never able to get it to work with UIView32 or APRSIS32 in KISS mode. The lack of modern Windows software for the extra data modes convinced me to convert my 1278 to a true TNC-2 clone so I could install a UIDIGI APRS digipeater EPROM which turns the 1278 into a stand-alone (no computer needed) APRS digipeater. As a TNC-2 clone any TNC-2 firmware ROM can be used. Even before the conversion the 1278 did a very good job of decoding packet and APRS. Details of the TNC-2 conversion can be found here:
N5NSL Rating: 3/5 Aug 20, 2003 02:51 Send this review to a friend
An OK TNC, CW, and RTTY decoder  Time owned: more than 12 months
I have three of the MFJ-1278 machines, all used, with my first machine coming from a hamfest in 1991. The MFJ-1278 has not been manufactured by MFJ in a few years, but MFJ still offers upgrades and parts for the 1278 and 1278B. This review discusses the 1278, which preceded the 1278B and 1278 DSP.

The Good:

The MFJ-1278 was built around the original TAPR packet TNC design and was primarily an extension of TAPR's original design. MFJ-1278 does VHF packet very well and also can be used to transmit beacon signals and transmit and receive morse code via CW and modulated CW (MCW). For packet, it also has a 32KB packet mailbox (expandable to 512KB) and can do AMTOR/NAVTEX and SSTV for those so inclined. There is Windows-based software for the MFJ-1278 called MultiCom dating from 1996. The software is effective in controlling and making operating the '1278 easier. But the TNC also is completely operational using anything which is or can act as an ASCII dumb terminal.
The controller can operate up to two radios, interfaces directly to a dumb terminal over a standard RS-232 connection, direct-drives a IEEE-1284 ("Centronics" parallel port) printer, and has provisions for a code key and output to a speaker. The newer models also had individual transmit audio level adjustments for each individual radio. On the face of the controller is a "Threshhold" knob (which is functionally like a variable audio input attenuator for the demod circuitry), a 20-segment LED tuning indicator usable for only HF modes (and randomly "hunts" otherwise), five or six status LEDS (DCD, PPT, STA, CON, TURBO (on some models with 2400 Baud modem boards), and PWR), and a push-in/push-out power switch. The manual is very technically detailed and very helpful in learning the operation and maintenance of the MFJ-1278.

The interesting:

The TNC has built-in facilities to assist in calibrating the TNC. The manual focuses on mostly operations and was written entirely in 12-point monospaced Courier, apparently from a typewriter or daisy-wheel printer.

The bad:

The greatest single problem I've found with the MFJ-1278 is self-generated RFI which emits to near-field radio antennas and circuitry either through the air or through cabling. While this is not even remotely a problem when in VHF modes, it is significant under some circumstances when operating in HF modes with HF receivers. The main points behind the RFI are insufficient shielding of cables off the '1278's main board and the use of standard computer ICs operating at standard voltages and current metrics for late-1980s computer components. Many of the chips made in the late 1980s (and today as well) readily radiate RF at some of the same fundamental frequencies used in HF radio transceiving. The Z80A CPU is slightly overclocked at 4.91 MHz, which doesn't affect stability, but tends to increase current switching in the Z80 CPU and fundamental and harmonic radiation. Unshielded AF cables from the TNC adjacent to HF antennas or some cabling can cause computer RFI to "talk over" the intended station, corrupting the signal. However, as I mentioned earlier, good shielding, good RF isolation inside the radio, and a remote antenna greatly improve the RFI issues. The MFJ-1278 has a sturdy metal case, but it's mostly the cabling which ducts the inner RFI out of the TNC and into the world around a few feet.


The MFJ-1278 is a fine TNC, but take due precautions regarding RFI and RFI isolation and shielding. There are better TNCs out there, some of which don't need RFI precautions. But the MFJ-1278 is OK.

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