Alternative transistors to 2n4427 @ 2cs1947 (used on NRG PLL PRO III - PRO IV boards)

[EFIALTISFM]

Hi all.

Has anyone used anything but the recommended 2n4427 @ 2cs1947 transistors with NRG PLL PRO boards ?

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The following list was compiled from information found in this forum on alternative transistors in general ( nothing specific to using them as alternatives on NRG boards)

2n4427 alternative: 2SC730, 2N3553, BLX65, BLY33, BLY34, MRF229, MRF629, TP8740, BFW16A, 2N5160

C1947 alternative: BFQ43, SD1127, MRF237, SD1127, NTE341, M9859, BLY35, PT31961

[sinus trouble]

Hello EFIALISFM

Unfortunately, ALL the "Alternatives" mentioned went obsolete years ago! The only choice left is copies or old remaining stock!

I would suggest designing something more up to date? However, Electronics these days moves so fast!

Your "New" components will likely become obsolete very soon!

Bad news aside? 60s technology is still alive among enthusiasts which gives a ray of hope!

If you are in the mindset of recreating history? The options are there!

Maybe you could try Enigma Shop? I recently Purchased 10 x 2SC1947s for a project i am working on right now!

[Albert H]

These days I'd go for the Mitsubishi 12V FETs - the RD01*** driving into the RD06*** would work (though the gain of the 06 is such that you might not need the intermediate stage).

I've just worked on an exciter circuit that uses a modern LMX-series PLL (controlled by an AT Tiny chip) and has a Kallitron oscillator (like the NRG stuff) but using FETs instead of the BF199s. It has a buffer stage using an RD01, and the final is an RD15 running at 10 Watts output. Between the RD01 and the RD15 there is a Soshin GBW3 filter to keep things clean, and the high gain of the RD15 means that the attenuation of the filter is overcome by the gain of the following FET.

The designer of the board had trouble achieving gain flatness across the band, but with some adjustment to track widths and a simple RF output monitor using a "sniff" of the output rectified with Schottky diodes to give a DC control voltage to adjust the gain of the RD01 stage, it delivers precisely 10 Watts on any frequency between 80MHz and 112MHz. The output falls off rapidly either side of those designed frequencies because of the action of the filter.

[EFIALTISFM]

Hi guys,

As always very informative and enlightening and... entertaining, but the question remains, if anyone has used alternatives on a NRG PRO board and how they preformed compared to the default (recommended by the builder) ones ?

Regarding the Mitsubishi MOSFETs that Albert mentioned, would it be possible to "install" on a NRG 3 or 4 board?

***

[reverend]

The Chinese 4427 copies can usually handle a Watt OK (though they seem very inconsistent)so may well be alright in the Pro boards. As for the 2SC1947, as Albert said, all of the alternatives are obsolete. If you can get any of the transistors you identified they ought to do a similar job. Note that not all have the same pinout as the 1947 though (some have Collector and Emitter swapped).

[rigmo]

You forget 2n3866 BFS23A

[rigmo]

These days I'd go for the Mitsubishi 12V FETs - the RD01*** driving into the RD06*** would work (though the gain of the 06 is such that you might not need the intermediate stage).

I've just worked on an exciter circuit that uses a modern LMX-series PLL (controlled by an AT Tiny chip) and has a Kallitron oscillator (like the NRG stuff) but using FETs instead of the BF199s. It has a buffer stage using an RD01, and the final is an RD15 running at 10 Watts output. Between the RD01 and the RD15 there is a Soshin GBW3 filter to keep things clean, and the high gain of the RD15 means that the attenuation of the filter is overcome by the gain of the following FET.

The designer of the board had trouble achieving gain flatness across the band, but with some adjustment to track widths and a simple RF output monitor using a "sniff" of the output rectified with Schottky diodes to give a DC control voltage to adjust the gain of the RD01 stage, it delivers precisely 10 Watts on any frequency between 80MHz and 112MHz. The output falls off rapidly either side of those designed frequencies because of the action of the filter.

I like RQA0009

[rigmo]

Hello EFIALISFM

Unfortunately, ALL the "Alternatives" mentioned went obsolete years ago! The only choice left is copies or old remaining stock!

I would suggest designing something more up to date? However, Electronics these days moves so fast!

Your "New" components will likely become obsolete very soon!

Bad news aside? 60s technology is still alive among enthusiasts which gives a ray of hope!

If you are in the mindset of recreating history? The options are there!

Maybe you could try Enigma Shop? I recently Purchased 10 x 2SC1947s for a project i am working on right now!

it's not outdated technologies, but our thinking... damn consumer society!

[yellowbeard]

In fairness the new stuff is definitely better in all respects, more gain, better efficiency, less heat, tougher, broadband, less stages for real power - and you can get them anywhere. And mark my words - the trimmer capacitor is next on the endangered/obsolete list, especially the high powered ones.

[sinus trouble]

In fairness the new stuff is definitely better in all respects, more gain, better efficiency, less heat, tougher, broadband, less stages for real power - and you can get them anywhere. And mark my words - the trimmer capacitor is next on the endangered/obsolete list, especially the high powered ones.

Oh yes! Without a doubt!

EFIALTISFM It all depends on what you are looking for?

[sinus trouble]

it's not outdated technologies, but our thinking... damn consumer society!

Rigmo! I am with you on that! Consumerism is riddled with greed and wastefulness!

Yet i cannot deny that it drives innovation too!

I guess there is good and bad in all things?

[rigmo]

it's not outdated technologies, but our thinking... damn consumer society!

Rigmo! I am with you on that! Consumerism is riddled with greed and wastefulness!

Yet i cannot deny that it drives innovation too!

I guess there is good and bad in all things?

the transition from lamps (tubes) to transistors is a huge shift.. a jump! unlimited amount of work.... today it should also be produced what people want and not what is imposed on them to buy! Transistor or field effect transmitters for everyone to choose from! talk about how to save energy, just don't hold water! if there is no money to pay for the operation of the station! don't even have it! whether the efficiency is 50% 60% 70% 80% is not important at all! play or not !

[jvok]

I have to agree with AlbertH and yellowbeard on this. Why fuck around with obsolete bjts when the new fets have more gain, are more efficient, easier to match, easier to make wideband and harder to kill? An RD01MUS2 will give you 1W+ with 10mW drive and barely get warm, even with no heatsink besides the pcb pads.

Mitsubishi RD series, MRF101 and MRF300. What else could you ever need?

Just needs someone to come up with an "NRG killer" thats as easy and reliable as the PLL pro but with modern parts.

[rigmo]

I have to agree with AlbertH and yellowbeard on this. Why fuck around with obsolete bjts when the new fets have more gain, are more efficient, easier to match, easier to make wideband and harder to kill? An RD01MUS2 will give you 1W+ with 10mW drive and barely get warm, even with no heatsink besides the pcb pads.

Mitsubishi RD series, MRF101 and MRF300. What else could you ever need?

Just needs someone to come up with an "NRG killer" thats as easy and reliable as the PLL pro but with modern parts.

Is not all in GAIN pal!
sorry... the object with which you observe the world has a deviation.
The MRF300 has a huge problem with heat dissipation!
RQA0009 more interesting series and also PD85xxx

[Albert H]

An RD01MUS2 will give you 1W+ with 10mW drive and barely get warm, even with no heatsink besides the pcb pads.

I did an exciter recently with just this device!. The oscillator was the NRG Kallitron two transistor type, with the Band II signal tapped off through a Soshin GBW3 filter to get rid of the ½f. This in turn drove the RD01, and I had a nice, clean, stable Watt. The PLL was a discrete CMOS job with diode programming, made with surface-mounted ICs, and the whole thing was nicely small. The whole exciter cost about £4! There are now ten of those exciters in Germany. They are going to drive MRF101 PAs, and be used in the Berlin area for a political pirate (not my thing, but hey-ho.....)

I'm going to correct the (minor) errors in the PCB layout and add a couple of additional facilities, and plan to get a pile of boards etched in the Far East. I'll make the Gerbers available to everyone once I'm fully happy with the layout.

[sinus trouble]

I have to agree with AlbertH and yellowbeard on this. Why fuck around with obsolete bjts when the new fets have more gain, are more efficient, easier to match, easier to make wideband and harder to kill? An RD01MUS2 will give you 1W+ with 10mW drive and barely get warm, even with no heatsink besides the pcb pads.

Mitsubishi RD series, MRF101 and MRF300. What else could you ever need?

Just needs someone to come up with an "NRG killer" thats as easy and reliable as the PLL pro but with modern parts.

Jvok! No one here is knockin the new technology!

I know as much about EFIALTISFMs motives as you do? He could be looking to refurbish vintage radio gear??

A next generation FET would seem a bit out of place in such a restoration?

From audio electronics experience? Some find the original artistic aspect more rewarding than the efficiency of the end product!

[EFIALTISFM]

Regarding OLD and NEW tech... each has its time and place!

I do enjoy using the old gear BUT I also love the new tech.

Would I spend time/$ to repair an 80's built 100w amp with a blown out transistor or would I go for a new build with say a MRF101A.
Logic and I would definitely go NEW... but if the obsolete component is nearby, I'd also repair the Oldie...

In closing, I started the topic out of interest to see out if anyone had used anything but the "default" transistors on a NRG PRO board and what the outcome/performance was. (was looking at a faulty NRG board with a sus 1947 and wanted to see what else I could "fit" in its place...)

[sinus trouble]

Regarding OLD and NEW tech... each has its time and place!

I do enjoy using the old gear BUT I also love the new tech.

Would I spend time/$ to repair an 80's built 100w amp with a blown out transistor or would I go for a new build with say a MRF101A.
Logic and I would definitely go NEW... but if the obsolete component is nearby, I'd also repair the Oldie...

In closing, I started the topic out of interest to see out if anyone had used anything but the "default" transistors on a NRG PRO board and what the outcome/performance was. (was looking at a faulty NRG board with a sus 1947 and wanted to see what else I could "fit" in its place...)

From experience! There is NO direct replacement device for any circuit!

Even two devices of the same part number will most likely not be identical!

You could redesign the NRG with the latest components if you have the competence and patience to do so?

Complex calculations are required in any new design to get you in the "Ball Park" of where you want to be?

This may still result in the perfect design not realised! Adjustments will be needed!

Whatever you choose? I wish you the best of luck!

[Albert H]

The problem with changing away from the '1947 is that the amplifier was designed to make best use of this device. Stephen spent weeks getting it right!

[EFIALTISFM]

Albert. Sinus,
I appreciate all your feedback and closing comments especially with Albert's "Moss" namedropping... the amp stays with a "new" 1947 as it was originally designed for.

Also a big thanks to Reverend, Rigmo, Yellowbeard and Jvok for their time and input.