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Speech Processor?

 

Greetings,
I have been considering adding a speech processor to my shack.
I was thinking it might give my TR5 a little help as they tend to be a little anemic, and maybe add a little to my B-line.
?
I am looking at the Drake SP-75, The Ten Tec 234 and the Daiwa RF-440
?
Any thoughts or opinions? Is it worth it? Any others I should look at?
?
Thanks,
Ed
KG5UN
 


When I tested several speech processors some years ago the TenTec unit was the worst by far when it came to intermodulation?distortion. I don't have any experience with?the other two.

On Sun, Apr 6, 2025 at 9:11?AM Ed KG5UN via <maikranze=[email protected]> wrote:
Greetings,
I have been considering adding a speech processor to my shack.
I was thinking it might give my TR5 a little help as they tend to be a little anemic, and maybe add a little to my B-line.
?
I am looking at the Drake SP-75, The Ten Tec 234 and the Daiwa RF-440
?
Any thoughts or opinions? Is it worth it? Any others I should look at?
?
Thanks,
Ed
KG5UN
 

I have used a SP75 for years with good reports. In the house I also have MFJ, Diawa, and a vintage Comdel, none of which I have tested (because SP75). Not impressed by the build of the MFJ but then I did not expect to be. The Diawa looks like it could be decent and they bring good $$ on the resale market (not that it means anything). Ken-Pro is re-basged Diawa and someimes cab be foThe Comdel is ... interesting. L/C filters, early solid-state construction. Datong is another that may be worth consideration. They seem to be sought after and don't come cheap. I've never had one.

Whatever you get make sure is explicitly states RF Speech Processor on the unit. If it doesn't than it isn't. Audio processors work but generally not as well. Note that the RF processors I mentioned above do work in the mic audio line. Avoid Magnum, they do not have the audio conversion and so work directly in the IF chain of the radio. As such they are rig specific and require modification to the rig.

On Sun, 06 Apr 2025 08:11:08 -0700
"Ed KG5UN via groups.io" <maikranze@...> wrote:

Greetings,
I have been considering adding a speech processor to my shack.
I was thinking it might give my TR5 a little help as they tend to be a little anemic, and maybe add a little to my B-line.

I am looking at the Drake SP-75, The Ten Tec 234 and the Daiwa RF-440

Any thoughts or opinions? Is it worth it? Any others I should look at?

Thanks,
Ed
KG5UN






--

73

-Jim
NU0C
 

Ed,
?
My suggestion would be to pair your TR5 with a Datong ASP, if you can find one for sensible money over there.
?
I acquired a Drake SP75 some while back and was curious as to how it sounded / performed in absolute terms and when compared with the Datong, when connected to my TR4310 and TR7 transceivers. My conclusion after some A/B testing and listening to my transmitted signal on a WebSDR (so over a real, noisy radio channel, not just monitoring clean / locally) was that the SP75 was quite good, but the Datong had the edge.
?
Both the Drake and Datong units are proper RF clippers. The Drake makes it's SSB using the filter method at 459 kHz, while the Datong makes it's SSB at 60 kHz using the phasing method. Both units feature audio compressors in front of the clipping stages to reduce the dynamic range of the audio baseband and thereby make the clipping process more effective.
?
To my ears, the SP75 sounded most useful / at it's best with next to no clipping action, i.e. just benefitting from the effect of the audio compressor. Adding clipping, I thought it started to sound less good at even quite modest levels (of clipping). By contrast, the Datong sounds at it's best with low to medium levels of clipping. Even at high levels of clipping, the Datong does not sound terrible, just over-processed / like a one man pile-up!
?
The Datong has been my go-to clipper for many years. With a Shure 444 driving it, it seems to pair well with any of my vintage SSB radio. It's quite a 'clever' design that uses unbuffered CMOS logic IC as analogue amplifiers in some parts of the circuitry. If needs be, it's still very mendable circa 40 years after it was first introduced. There's an article (linked below) where a chap was having trouble with the carrier oscillator / resonator and filters in an SP75.
Replacements for those parts are certainly hard to come by over here (so I hope mine never go faulty)!
?
Regards,
?
Mark, G4FPH.
?
 

¿ªÔÆÌåÓý

Thanks mate. I was not aware of that one so I will now begin a search. I will probably grab Sp-75 just to have one as well.?
73,
Ed
KG5UN?

On Apr 6, 2025, at 3:42?PM, atlasstuff via groups.io <g4fph@...> wrote:

?
Ed,
?
My suggestion would be to pair your TR5 with a Datong ASP, if you can find one for sensible money over there.
?
I acquired a Drake SP75 some while back and was curious as to how it sounded / performed in absolute terms and when compared with the Datong, when connected to my TR4310 and TR7 transceivers. My conclusion after some A/B testing and listening to my transmitted signal on a WebSDR (so over a real, noisy radio channel, not just monitoring clean / locally) was that the SP75 was quite good, but the Datong had the edge.
?
Both the Drake and Datong units are proper RF clippers. The Drake makes it's SSB using the filter method at 459 kHz, while the Datong makes it's SSB at 60 kHz using the phasing method. Both units feature audio compressors in front of the clipping stages to reduce the dynamic range of the audio baseband and thereby make the clipping process more effective.
?
To my ears, the SP75 sounded most useful / at it's best with next to no clipping action, i.e. just benefitting from the effect of the audio compressor. Adding clipping, I thought it started to sound less good at even quite modest levels (of clipping). By contrast, the Datong sounds at it's best with low to medium levels of clipping. Even at high levels of clipping, the Datong does not sound terrible, just over-processed / like a one man pile-up!
?
The Datong has been my go-to clipper for many years. With a Shure 444 driving it, it seems to pair well with any of my vintage SSB radio. It's quite a 'clever' design that uses unbuffered CMOS logic IC as analogue amplifiers in some parts of the circuitry. If needs be, it's still very mendable circa 40 years after it was first introduced. There's an article (linked below) where a chap was having trouble with the carrier oscillator / resonator and filters in an SP75.
Replacements for those parts are certainly hard to come by over here (so I hope mine never go faulty)!
?
Regards,
?
Mark, G4FPH.
?
 

Datong ASP.
?
Works well.
?
73

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