There were thousands of these receivers sold to, and in use by, many "3-letter" government agencies around the
world. I recently obtained 2 more of them which I've given the full "N1KPR Mod Package."
The Venerable IC-R71A
Legal Stuff - READ THIS:
The following mods are offered here with the understanding that you already have the experience and skill to perform such work. You
must have the R71A service Manual and schematic to do this safely. Do not ever open any electronic equipment enclosures without
disconnecting all mains power and/or if you are not qualified to perform such work. i am not responsible for any mistakes you make or
the results of these mods to your equipment. I have performed these modifications and can attest to their utility, but offer it here as
|This page just touches what can be done to this radio.
Recommended reading: Icom R71 Performance Manual. By Donald Moman.
Available on the Internet along with many other helpful mods -- do a search.
Also, join the Yahoo R71a Group
1. AM Broadcast band (MF) Attenuator removal.
R11, R12, R13 form an AM Band attenuator. These are on the RF PC Bd on the right side of the radio.
Cut the exposed lead of R13 (33 Ohms) and short R11 to R12 (top of R12 to far end or R11). If you
remove the Bd it will be easier, but it's not required to make the mod. This mod will give you
increased sensitivity in the BCB. If you have a local flame thrower in the area, you may experience
overload and need to use the front panel Attenuator on occasion.
2. On the same RF Bd, locate D23 and D24. These are preamp-inhibit diodes for the BCB and LF bands.
Cut one end of each which allows the internal preamp to be used (from the front panel) as desired.
The preamp circuit has limited gain below .7 or .5 MHz so the gain will be less than experienced in the
SW (HF) bands.
3. Notch function in AM Mode. On the Main Bd - top of set. Connect a 27K to 47K resistor from the
junction of R124 and W29 to R103 (on the W29 side).
4. Extra filter facilities. At the top left of the receiver is a space for an optional filter. This is usually
empty. I installed a 47 Ohm resistor in that space (and enabled the optional filter slide switch next to
it). Although this is somewhat of a hack-mod, it does allow some extra flexibility with the passband
control. Study the schematic and you can see the results.
5. Add a 455KHz output. I drilled a hole on the Accessory plate on the rear apron and added an RCA
jack. From there I ran about 6" of RG174 to a .02mf capacitor and then to diode D29 anode (or D28). i
use this tap for the KIWA MAP which is a synchronous detector and IF/AF filter. I have not tried it, but
I'd guess that the Sherwood SE3 mods require some similar arrangement - check with Sherwood
The KIWA unit is very rare. If you see one - buy it! They were very expensive to build and not many
were ever manufactured (pic below). Although, KIWA currently provides many receiver aids and mods,
<http://www.kiwa. us >
6. (Maybe this should be item No. 1) Extended LF receive and Non-Volitle RAM. Install the RAM/ROM
board offered by Willco Electronics. <www.willcoele.com>
This mod will allow the R71A to tune down to 10KHz! And the best part is that if the lithium memory
battery ever fails, all you loose is your stored memories - not the entire operating system (back to
Icom for service).
The Willco board is well worth the investment...believe me - shipping the radio both ways would have cost enough to pay for the
Willco board. I am not associated in any way with Willco Electronics, but I am a very happy, repeat customer.
The KIWA MAP (Multiband AM Pickup)
Here it resides with a JRC NRD-515 and my
homebrewed Type-5 preselector.
What a winning combination!
The MAP (KIWA) connected to one of the
recent Icom R71A (modded) radios.
Again, this brief page really just touches on
useful mods -- please read:
Icom R71 Performance Manual. By Donald
Moman and do a search on IC-R71A Mods