JRC NRD-535 (Lowe) filter issue. - UK Vintage Radio Repair and Restoration Discussion Forum

Sputniksam · 12th Sep 2022, 10:20 am

Hi

Very recently I purchased a JRC NRD-535 receiver. I believe it to be a Lowe version as it has the little Lowe badge and is equipped with the ECSS board and a Narrow (1KHz) Filter option. The receiver has outstanding performance, as expected, except in one area. When I select the standard wide bandwidth setting (6KHz), switching in the CFL-D6S ceramic filter, the receiver’s sensitivity drops significantly. As an example Radio 5 Live is a very strong 30+dB signal on all filter selections except for the wide setting where it will drop to a S5. More scientifically if I provide a calibrated 50uVolt signal I get S9 on all filter selections except for the wide setting where it will register approximately s3 or so. With 1uV input the signal is still perfectly audible on all filter selections except for the Wide selection where there is just noise.

I don’t have any extender boards for this radio so I can’t test things in situ. I’ve passively checked as best I can the diodes used in the switching and they appear to be ok. I’m leaning toward the notion that for whatever reason the CFL-D6S ceramic 6KHz filter may have degraded. It would be a simple task replacing it but these devices appear to be as rare as unicorn eggs these days.

I would be very appreciative if anyone with a greater working knowledge than myself of this radio could provide insight and advice. Are my assumptions correct? Or am I barking up the wrong tree in my diagnosis?

Regards

Nidge (G0NIG)

John KC0G · 13th Sep 2022, 1:45 am

Hello Nidge

I had a quick look at the circuit diagram. It appears to me that this filter is FL3, and it has a dc voltage applied to it. This is not at all good for ceramic filters, and should be avoided. This may well have led to a degradation of the filter. See, for example: https://www.amateurradio.com/deterio...ers-due-to-dc/

It seems to me that the NTK CLF-6DS is a reduced size version of the CLF-6D. The latter can be found here in the USA, but the shipping costs will start at $15. There will have been Murata equivalents to both.

Please check the above, and ask if you have futher questions.

HTH and 73

John KC0G/M0KCY

John KC0G · 13th Sep 2022, 8:15 am

I should have said CLF-D6S and CLF-D6.

Sputniksam · 13th Sep 2022, 11:23 am

Thank you for the reply and advice John.

I’d heard, and experienced, the many tales of filters being damaged in the Yaesu 8XX series of radios and some of Kenwood’s TS2000’s, but possibly I’m the first to experience this with a JRC product as I’ve yet to find any documentatec cases other than my own.

I’ve managed to locate a limited supply of CLF-D6S’s and I’m just waiting for the seller to confirm his postage charges.

The price I paid for this NRD-535 is such that I don’t mind spending the extra time and money on bringing it up to spec and possibly adding some of the luxury items that were offered as options in the UK. In a previous life I was a marine radio officer and one of the receivers in the radio room was a JRC-240, which I coveted, along with Skanti R5001’s. In later years I worked mainly with Racal’s (1792 and 3712) and WJ gear. But the JRC was unique in that the covers never had to be removed. I recently started yearning for a proper “spin and grin” radio (All my other receivers are SDR’s) and this JRC-535 just happened along at the right time and at the right price.

Regards

Nidge (G0NIG).

majoconz · 13th Sep 2022, 9:24 pm

Nidge - you must have followed me around - I was a Sparks too. One of my ships was the "Allamanda" of SAFMarco but was originally a Maersk tanker with Skanti and Pedersen gear and I finally managed to get a Debeg 7313 which is the Skanti 5001 rebadged - after a bit of a cleanup it works very well - I rehoused it in a homemade console with other 19" rack gear. Can't remember which ship had the JRC gear with two NRD505's and much later I scored a 515 from the JAL office at Auckland airport unused - built like a tank and works very well - might have been the Naess Sovereign.

Sputniksam · 15th Sep 2022, 10:04 am

“ Nidge - you must have followed me around - I was a Sparks too.”

By the sounds of it you were in the real merchant navy. I was part of what I believe was referred to as the “G&T Navy”. I was at see for only a short while as one of the RO’s aboard the QE2. I got my ticket just as everything was changing for Radio Officers and in 1992 I jumped ship and accepted a position with the intelligence services, where I remained until 2014, when I was forced to retire due to a degenerative illness. However I still consider the brief time I was at sea to be the best time of my life, and if I could I would have no hesitation in going back.

Nidge (G0NIG).

Sputniksam · 22nd Sep 2022, 3:42 pm

The replacement CLF-D6S (NTKK) filters that I ordered from the German Ebay Seller arrived this morning. I've just installed one into my NRD-535, and the good news is everything is working as it should.

The next job is to install the CFL-243W board when it arrives in the next few days to make my radio into a NRD-535D.

Nidge (G0NIG)

12th Sep 2022, 10:20 am	#1
Sputniksam Diode Join Date: Sep 2022 Location: Otley, West Yorkshire, UK. Posts: 5	JRC NRD-535 (Lowe) filter issue. Hi Very recently I purchased a JRC NRD-535 receiver. I believe it to be a Lowe version as it has the little Lowe badge and is equipped with the ECSS board and a Narrow (1KHz) Filter option. The receiver has outstanding performance, as expected, except in one area. When I select the standard wide bandwidth setting (6KHz), switching in the CFL-D6S ceramic filter, the receiver’s sensitivity drops significantly. As an example Radio 5 Live is a very strong 30+dB signal on all filter selections except for the wide setting where it will drop to a S5. More scientifically if I provide a calibrated 50uVolt signal I get S9 on all filter selections except for the wide setting where it will register approximately s3 or so. With 1uV input the signal is still perfectly audible on all filter selections except for the Wide selection where there is just noise. I don’t have any extender boards for this radio so I can’t test things in situ. I’ve passively checked as best I can the diodes used in the switching and they appear to be ok. I’m leaning toward the notion that for whatever reason the CFL-D6S ceramic 6KHz filter may have degraded. It would be a simple task replacing it but these devices appear to be as rare as unicorn eggs these days. I would be very appreciative if anyone with a greater working knowledge than myself of this radio could provide insight and advice. Are my assumptions correct? Or am I barking up the wrong tree in my diagnosis? Regards Nidge (G0NIG)

13th Sep 2022, 1:45 am	#2
John KC0G Hexode Join Date: Mar 2009 Location: Minneapolis, Minnesota, USA. Posts: 278	Re: JRC NRD-535 (Lowe) filter issue. Hello Nidge I had a quick look at the circuit diagram. It appears to me that this filter is FL3, and it has a dc voltage applied to it. This is not at all good for ceramic filters, and should be avoided. This may well have led to a degradation of the filter. See, for example: https://www.amateurradio.com/deterio...ers-due-to-dc/ It seems to me that the NTK CLF-6DS is a reduced size version of the CLF-6D. The latter can be found here in the USA, but the shipping costs will start at $15. There will have been Murata equivalents to both. Please check the above, and ask if you have futher questions. HTH and 73 John KC0G/M0KCY

13th Sep 2022, 8:15 am	#3
John KC0G Hexode Join Date: Mar 2009 Location: Minneapolis, Minnesota, USA. Posts: 278	Re: JRC NRD-535 (Lowe) filter issue. I should have said CLF-D6S and CLF-D6.

13th Sep 2022, 11:23 am	#4
Sputniksam Diode Join Date: Sep 2022 Location: Otley, West Yorkshire, UK. Posts: 5	Re: JRC NRD-535 (Lowe) filter issue. Thank you for the reply and advice John. I’d heard, and experienced, the many tales of filters being damaged in the Yaesu 8XX series of radios and some of Kenwood’s TS2000’s, but possibly I’m the first to experience this with a JRC product as I’ve yet to find any documentatec cases other than my own. I’ve managed to locate a limited supply of CLF-D6S’s and I’m just waiting for the seller to confirm his postage charges. The price I paid for this NRD-535 is such that I don’t mind spending the extra time and money on bringing it up to spec and possibly adding some of the luxury items that were offered as options in the UK. In a previous life I was a marine radio officer and one of the receivers in the radio room was a JRC-240, which I coveted, along with Skanti R5001’s. In later years I worked mainly with Racal’s (1792 and 3712) and WJ gear. But the JRC was unique in that the covers never had to be removed. I recently started yearning for a proper “spin and grin” radio (All my other receivers are SDR’s) and this JRC-535 just happened along at the right time and at the right price. Regards Nidge (G0NIG).

13th Sep 2022, 9:24 pm	#5
majoconz Heptode Join Date: Jan 2008 Location: Ashhurst, Manawatu, New Zealand Posts: 570	Re: JRC NRD-535 (Lowe) filter issue. Nidge - you must have followed me around - I was a Sparks too. One of my ships was the "Allamanda" of SAFMarco but was originally a Maersk tanker with Skanti and Pedersen gear and I finally managed to get a Debeg 7313 which is the Skanti 5001 rebadged - after a bit of a cleanup it works very well - I rehoused it in a homemade console with other 19" rack gear. Can't remember which ship had the JRC gear with two NRD505's and much later I scored a 515 from the JAL office at Auckland airport unused - built like a tank and works very well - might have been the Naess Sovereign. Attached Thumbnails __________________ Cheers - Martin ZL2MC Last edited by majoconz; 13th Sep 2022 at 9:32 pm.

15th Sep 2022, 10:04 am	#6
Sputniksam Diode Join Date: Sep 2022 Location: Otley, West Yorkshire, UK. Posts: 5	Re: JRC NRD-535 (Lowe) filter issue. “ Nidge - you must have followed me around - I was a Sparks too.” By the sounds of it you were in the real merchant navy. I was part of what I believe was referred to as the “G&T Navy”. I was at see for only a short while as one of the RO’s aboard the QE2. I got my ticket just as everything was changing for Radio Officers and in 1992 I jumped ship and accepted a position with the intelligence services, where I remained until 2014, when I was forced to retire due to a degenerative illness. However I still consider the brief time I was at sea to be the best time of my life, and if I could I would have no hesitation in going back. Nidge (G0NIG).

22nd Sep 2022, 3:42 pm	#7
Sputniksam Diode Join Date: Sep 2022 Location: Otley, West Yorkshire, UK. Posts: 5	Re: JRC NRD-535 (Lowe) filter issue. The replacement CLF-D6S (NTKK) filters that I ordered from the German Ebay Seller arrived this morning. I've just installed one into my NRD-535, and the good news is everything is working as it should. The next job is to install the CFL-243W board when it arrives in the next few days to make my radio into a NRD-535D. Nidge (G0NIG)