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N8YX
04-16-2011, 09:39 AM
Summary: A capable performer which can hold its own with any of its modern-day contemporaries

Introduced in the mid-80s and enjoying an 11-year production run, the R-71A soon became a favorite of DXer, ham, ute listener and commercial user alike. A goodly number of the receivers were pressed into service by the NSA and other government agencies; these radios (some of which were modified for remote control and TOR duties) can occasionally be found on eBay.

Sherwood claims synthesizer phase noise figures for the -71A to be almost 20dB less than the Drake R7 at the same frequency separation points. The Icom is a little noisier with no antenna connected (as the RX Test figures bear out) but once a decent aerial is attached, this point becomes moot.

You get 32 memories (tunable), PBT (earlier runs), a notch filter, a tone control, preamp/attenuator, FM reception (w/ option board), remote control (w/option), computer control via CI-V port (option) selectable filtering and an effective dual-width noise blanker all in a stable platform. Icom offered the CR-64 TCXO but I really don't see the need for it...not at $150 per copy, and that's assuming you can find one.

The rig is not without its Achilles Heels: Icom put the CPU firmware in volatile memory, itself backed up by a lithium coin cell. If the cell goes bad, so does the firmware. There are fixes:

Nardo's replacement memory board
Piexx's equivalent of same
Willco Electronic's board
Reprogram the stock unit (instructions are available on the web)

Two other gotchas:

1) The VCO lock-adjustment trimmer caps are made of plastic and will occasionally go bad. Replace them with ceramics, retune the individual VCO loops (per the service manual) and you're good to go.
2) These rigs (along with the R-7000 and most other Icom radios of the period) use a DC-DC converter to develop voltages required to operate their VFD readouts. The electrolytic filter capacitors used in the circuit are being run very close to their maximums and will sometimes fail, leading to partial or total blanking of the display. The fix is easy: Replace every electrolytic (a total of 9) in the circuit. I recently had to do this with a new acquisition. It took longer to type this review than it did to fix the problem - once I knew what to look for.

Icom offered a CW filter - the FL-32 - as an option, and an FL-44 (8 pole, 2.4KHz, 455KHz C/F) SSB filter could be installed as an alternative to the 2.4KHz 6-pole Murata unit which was included as "stock". All of the receivers in use here have the -32 fitted but I'm eventually going to go with Inrad's 1.9KHz B/W SSB filter instead of the Icom unit.

Bear in mind this is a non-DSP unit. A BHI, SGC or similar audio DSP accessory could be fitted, much as I did with the R-7000 (see the "Modifications" forum for a writeup). Since the R-71A already incorporates a very effective notch filter and offers filter bandwidth selection controls on the front panel, the SGC unit and its auto-notch function is probably overkill in this application.

Icom also provided the ability to externally mute the rig, enabling it to be used in conjunction with a transceiver. This arrangement works rather well and if both receiver and transceiver are connected to a PC running HRD or a similar rig control/sync program, they can be used in an SO2R capacity.

K6BSO
04-16-2011, 12:27 PM
I've got the IC-R71's successor, the IC-R75. Great little radio, I sometimes use it instead of the receiver on my IC-736 when conditions are noisy.

By the way, the R75 is what got me back into ham radio—I bought a used one for SWLing, but then discovered that there's not as much of that as there used to be thanks to the Internet. Then one night I was looking for the BBC and stumbled on to the 40m amateur band. I had my ticket a month later.

N8YX
04-16-2011, 01:04 PM
I've got the IC-R71's successor, the IC-R75. Great little radio, I sometimes use it instead of the receiver on my IC-736 when conditions are noisy.
Talk about your coincidences - immediately after I typed this up, I started looking into an R-75/IC-718 pair for FD use. Have you any experience with the '718?

K6BSO
04-16-2011, 01:22 PM
No, but I think it's essentially an IC-R75 with a transmitter attached (or a transmitter using an IC-R75 as a receiver, however you want to look at it). They're almost exactly the same size.

WX7P
04-16-2011, 07:47 PM
Talk about your coincidences - immediately after I typed this up, I started looking into an R-75/IC-718 pair for FD use. Have you any experience with the '718?

I have a 718 with the DSP option. I'd still be using it as the main rig if NPN hadn't of bought me a 746 pro a year later.

Good radio! Except no FM

N8YX
04-17-2011, 06:17 AM
I have a 718 with the DSP option. I'd still be using it as the main rig if NPN hadn't of bought me a 746 pro a year later.

Good radio! Except no FM
What do you think of the radio's noise floor, Dave? A lot of Eham reviews mention an excessively noisy receiver, though with the one example I've used it's really hard to tell - as that was in a location plagued by poor antennas and an extreme amount of RFI.

N8YX
06-27-2011, 06:02 PM
Just got hold of an Inrad #322 (1.8KHz) filter for one of the R-71As and installed it in place of the Murata CJF455K5 (2.8KHz, 6-pole) unit which came with the rig. That slot was originally meant for an Icom FL-44A (2.4KHz b/w; 8-pole) filter but the IC-751A I've paired with this particular R-71A already has a -44A installed. A little bugaboo: If one installs a narrow SSB filter in a -751 then selects it via the front panel "Narrow" switch, that filter is placed in the transmit - as well as the receive - audio chain.

Bad, Icom, BAD. Heck, even Drake, Collins and Kenwood had that one figured out years before!

Thus, the receiver got the Inrad. Probably a good thing, as that puppy is tight. Given the fact that receiver sees its heaviest SSB use in QRM-infested parts of the HF spectrum, a narrow(er) filter makes sense. Its overall passband isn't as easy on the ears as the stock Murata (or even the FL-44A) but it looks to be the ticket for SSB monitoring on a crowded band.

Between the newly modified R-71A and the IC-751A I have the following selectivity options:

6KHz
3.2KHz
2.4KHz
1.8KHz
500Hz
250Hz

Slave the two together and you can pick a bandwidth which is suitable for any task - with the possible exception of 850Hz-shift FSK, but Inrad makes a filter for that too.

At $170 plus shipping, this filter ain't cheap...but if one pops up on the various ham sale sites or eBay you can sometimes get a deal. I'll eventually buy two more so that all the shack's R71As are outfitted. Too bad there isn't a way to run both the FL-44A and the 322 (as I can with my Drake 7-line) but them's the breaks.