Sherwood Engineering Incorporated Sherwood Engineering Incorporated
1268 South Ogden Street Denver, Colorado 80210 USA
email     Phone:
303-722-2257     FAX: 303-744-8876    
9 a.m. - 5 p.m. MST Monday - Friday
Japan Radio NRD - 515 Japan Radio NRD - 525 / 535 Japan Radio NRD - 345
Japan Radio NRD - 545 DSP Protection Filter Replacement Japan Radio Authorized Dealer
Icom R9000 PRE-4 Preamp Icom R8500
Drake R-8 & R-8A HF1000 Interface Short Wave Radio to SE-3
Sherwood Engineering Inc. Home Page Amateur Radio Products SE-3 MK III

Japan Radio NRD-515

A modification is necessary to use a 515 with the Sherwood SE-3 phase-locked detector. The internal AM detector causes intermodulation distortion (IMD) of the i-f signal. This distortion is accurately (and annoyingly) reproduced by the wide-band SE-3. An FET buffer is installed in the 515 to isolate its detector from the i-f, eliminating the problem.

Japan Radio NRD 515

The 515's versatility is limited by its modest selection of AM bandwidths. We offer custom accessory-filter PC boards to solve this problem. With our two-filter board, a 9 or 15-pole 8-kHz ceramic filter can be added to improve the muffled audio that occurs with the standard AM filter. This board will accommodate two ceramic filters or one ceramic and one crystal filter.

Optimization of the Sherwood filters, plus a vast improvement in performance of the existing AM filter can be realized with circuit changes on the main receiver board. A 30-dB increase in ultimate rejection of the standard filter is typical.

For those who need more than two accessory filters, step up to the 4-filter switching board. This plug-in board allows six filters to be selected from the front panel.

Please feel free to contact us to discuss selection of filter bandwidths best suited to your needs and interests.

NOTE: For an additional $15.00 US, our lab will provide you with a hard-copy 90-dB filter plot of your modified radio. See the actual bandwidth and rejection characteristics of your JRC/Sherwood NRD-515.

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Japan Radio
NRD-525 / 535

A modification is necessary to use the NRD-525 or 535 with the Sherwood SE-3 phase-locked detector. An i-f output must be added to the set to feed our unit. A 9-volt 30-mA output on rear of the set can be rewired to provide i-f output, or a jack can be added. The i-f board can still be unplugged as before.

Japan Radio NRD 535

We recommend the addition of our 9-pole CN-8000 8-kHz filter with shape factor of 1.7:1. Other choices include 14, 6, and 3.8 kHz units. Our 9-pole filters can replace the existing AM filter. We can also install JRC 1.8- kHz or 1.0-kHz filters, though their CW filter is not recommended due to poor shape factor.

The Sherwood CN-400 is suggested for CW & narrow-shift RTTY reception:

NOTE: For an additional $15.00 US, our lab will provide you with a hard-copy 90-dB filter plot of your modified radio. See the actual bandwidth and rejection characteristics of your JRC/Sherwood NRD-525.

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Authorized Dealer Japan Radio

Authorized service center for JRC products. Sherwood modifications also offered.


Japan Radio NRD-345

This is the best sub $1000.00 radio on the market. It has the quality and feel of all JRC products at a modest price. When teamed with the SE-3 Mk III Standard or Deluxe, this package offers superior audio reproduction and great DX listening. You do not have to give up great ergonomics to have an affordable radio. Requires BUF-3: $55.00.

Japan Radio NRD 345

Eliminate AGC Attack Distortion on AM
The AGC attack speed of the 345 is way too slow. We can modify the radio to eliminate this problem, providing the same fine AGC on AM as on SSB.

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Japan Radio NRD-545

This is JRC's current production DSP Radio. It has the quality and feel of all JRC products. This unit is not compatible with the SE-3 Mk III. This receiver offers superior band width flexibility with a turn of a knob. UHF converter and TCXO accessories available.

Japan Radio NRD 545

DSP Protection Filter Replacement
The DSP (digital signal processor) chip in the 545 is proceeded by a 15 kHz 9 pole ceramic filter. This protects the digital processor from strong station that are 10 kHz or more away. On shortwave bands however, very strong adjacent-channel signals are only 5 kHz away and can overload the DSP chip. We offer a replacement filter that is 8 kHz wide instead of 15 kHz, which attenuates 5 kHz off frequency by 40 dB. This modification reduces the maximum bandwidth of the radio from 9.9 kHz to 8 kHz. A modest trade-off for significantly improved adjacent-channel overload characteristics.

Field installation is possible but very good desoldering tools are required or serious damage can occur to the processor board.

For extremely serious DXers we also offer a 6 kHz 9 pole replacement filter. Maximum user adjustable bandwidth drops from 9.9 kHz to 6 kHz with this filter change. NBFM on 10 meters not usable with the 6 kHz filter option.

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Make the R9000 the Ultimate Receiver!

The fantastic Icom R9000 receiver is near perfect except for two areas:

  • Poor AM selectivity choices
  • No synchronous detector
R9000 Receiver

Sherwood offers the following modifications for this fine radio.

Enable the 6 kHz filter that is only used on SSB, and add the needed switching logic for Standard and Custom filter selection.

Stock selectivity on AM: 15 kHz, 9 kHz and 3 kHz.

Custom selectivity on AM: 15 kHz, 9 kHz, 6 kHz, and 3 kHz.

NOTE: With our logic board you get all four bandwidths listed above.

Second, add the necessary down converter to provide an IF output at 455 kHz for our world-renowned SE-3 Mk III synchronous AM detector.

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PRE-4 Preamp

10 dB high-dynamic range preamp. Relay switched when DC supplied. +33 dBm input intercept. Similar to preamp in Drake R-7 receiver. Operates on 12 to 14 volts DC at 100 mA. Rated at 500 kHz to 50 MHz, though usable above and below that frequency. Switchable from front panel of Icom R-9000 receiver.

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Optional 4 kHz AM filter in narrow CW position: $99.00.

Icom R8500 HF / VHF / UHF Radio

IF output for SE-3 requires the BUF-3 board: $55.00. Installation $129.00.

Icom 8500
Click Here for Full SE-3 Details

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Drake R-8 and R-8A

The SE-3 synchronous detector provides a dramatic improvement in shortwave AM reception when used with the Drake R-8 and R-8A. (See separate section devoted to the SE-3 on this web site) Problems with the internal Drake sync detector continually going out of lock are eliminated by using our external detector/amplifier. Both radios need our up-conversion / buffer boards to provide the proper 455 kHz IF output signal to drive the SE-3 Mk III. Due to the up-conversion from 50 kHz to 455 kHz, the BUF-3 board requires an enhanced clean-up filter.

The R-8 can also be improved with our AGC overshoot correction circuitry. This modification adds a three position toggle switch to the rear of the radio which offers two levels of AGC dampening plus the stock (original) operation.


Watkins-Johnson & Ten-TEC DSP Radios
The WJ HF1000 & 8711A, and Ten-Tec RX-340 are SE3 ready. IF output on rear of radio feed SE-3 input.

HF1000


More Information On Interfacing a Shortwave Radio to the SE-3   Amateur Radio Products

Sherwood Engineering Incorporated Sherwood Engineering Incorporated
1268 South Ogden Street Denver, Colorado 80210 USA
email     Phone:
303-722-2257     FAX: 303-744-8876
9 a.m. - 5 p.m. MST Monday - Friday

Updated 6 March 2006