TMC CV 591 Product Detector

[flintstone mop]

I would like to get a technical opinion on this piece of equipment. The CV 591 seems to be a very robust product detector used with the R390A or any radio with 455 I.F.
Anything super about it? Capable of superior hi-fi audio? Or was the focus on SSB reception only?
I monitor on the Diode Load and that may not be best for superior Hi-Fi audio...........dunno
Was there ever a modern solid state version of this box that would be more affordable?
The original TMC box still commands $600-$900 on various sites. Fair Radio has them, every now and then.
Thanks
Fred

[N8ETQ]

Hey Fred,

    It won't sound as good as your diode load hookup.
I worked on a few of these for a cust. a year ago or
so, and they work fine but only one audio path.
 
    The best sounding of the crop is CV-157 with
2 audio chanels and 2 sideband filters, AFC (Motorized)
and a pretty decent AGC. You can get a "Near" stereo
effect when the thing locks up on an AM signal. The
60 cy. wide carrier filter makes it a little "Bothersome"
to use in a roundtable. If the carrier is not in the passband
the motor always seem to tune the wrong way.

    I built a synch detector from an article in some
radio rag years ago that used a PLL and a couple
audio chips that sounded pretty good.  I see a few
commercial jobs on E-pay from time to time.

Here is a link to the manual for the CV591

http://www.qsl.net/w6ger/pdfdocs/CV591a.pdf

    I think anything with a good strong locally
generated carrier will give good results the
weakness is in the audio channel. (s) of which
there ain't enough of.  Even an R-1051 in ISB
sounds pretty good for the same reasons.

73

/Dan
   

[w3jn]

The CV-591's audio is pretty horrible.  It's main use is as a product detector, but also provides a passband tuning utility.  It has a 17KHz or so IF which affords fairly narrow filtering.

For AM use, it's pretty useless unless you want better selectivity and passband tuning.

[flintstone mop]

thanks for the replies.
One day I might get that Sherwood SE 3...used ........maybe....
Fred

[nq5t]

The 591 isn't a complete dog on SSB, and it does add some selectivity if the base receiver doesn't have it.  The biggest downside besides audio is that the built in AGC is very poor, and TMC never fixed it -- except maybe in the last of the family, the MSR-9.  I've had a couple of them, and got rid of them.  Very "wooly" on AM, and essentially useless IMO.

I now have a GSB-1 (which has the same signal path circuitry as the 591) on my GPR-90 and it performs ok, but even though they are supposed to work together, I had to pad down the IF input to the GSB-1 to tame the the GSB-1 AGC action.  I also modified the GPR-90 AGC to help out a bit as well. (Running with GSB-1/591 on SSB with the internal AGC off does not work well at all).

The SE-3 does an excellent job on sideband on any receiver I've tried it on (including that GPR-90) although it does not add any additional selectivity.  And unless you get lucky, a nice 591 in working condition will set you back way more than its performance is worth, and nearly as much as an SE-3.  I don't know why the prices of the 591 remain so high ...

[WQ9E]

My favorite of the external adapters is the Hammarlund HC-10. It adds the 60Khz IF strip, slot filter, AGC, product detector, and audio section found in the HQ-170/180 to any set with a 455 Khz. IF output.  The HC-10 works well on all modes, provides selectable sideband on AM,  and provides a great improvement in selectivity for many vintage receivers.  I used one with my GPR-90 until I found a GSB-1 which I now use with the GPR-90 but to be honest the HC-10 provides much better performance and is far more versatile.  I also have a GPR-92 with a second GSB-1, I must be a glutton for punishment

I have a HC-10 paired with a HQ-160 and this makes a very versatile combination.  The audio direct from the HQ-160 can be used when conditions are good allowing better fidelity and the HC-10 steps in for SSB/CW and when conditions are rough on AM where it provides choice of the AM sideband with least interference. 

I have thought several times of turning a parts SX-101 or similar into a Hallicrafters version of the HC-10.  Unlike Hammarlund which changes both passband width and frequency when selecting sidebands and changing selectivity the Hallicrafters approach switches sidebands via the conversion oscillator frequency (either above or below mixed IF frequency) so all the switching has to do is provide for choice of bandwidth.  The Hallicrafters approach provides the equivalent of 10 Khz. DSB bandpass down to 500 hz for CW.

[flintstone mop]

Roger Roger
Thanks for the info on the Hammarlund HC10. It might be worth looking into.
I understand what folks are saying about the Diode load on the 390A, but is there really a clear audio advantage to a product detector?
Thanks
Fred

[N8ETQ]

Roger Roger
Thanks for the info on the Hammarlund HC10. It might be worth looking into.
I understand what folks are saying about the Diode load on the 390A, but is there really a clear audio advantage to a product detector?
Thanks
Fred

  Hey Fred,

     The product detector is kind of required for the
locally injected carrier which is strong and stable.
The recieved carrier is either fading (AM) or absent
(SSB). As long as the Local carrier can be phase locked
to the recieved carrier the adapter will enjance the
AM audio signal. Seems it takes less carrier to phase
lock a PLL than it does to properly demodulate an AM
sideband. Hence the need for product detector.(s)

     On SSB the AFC is shut off to allow just the use
of the product detecter.(s) which is/was the point for
the CV 591 and the CV-157. The CV 591 does not suport
phase lock to the recieved carrier therefor is esentially
an external product detector relying on the stability
of the RX involved. With the CV-157 you can choose to
use the Recieved carrier or the Local carrier for
demodulation.

     I assumed you were looking for the "Ultimate"
AM detector for HI-FI reception. If you just want to
copy SSB cleaner any of the above mentioned devices will
work fine. 

     Clear as Mud, right?

/Dan

[flintstone mop]

Roger Roger
Thanks for the info on the Hammarlund HC10. It might be worth looking into.
I understand what folks are saying about the Diode load on the 390A, but is there really a clear audio advantage to a product detector?
Thanks
Fred

  Hey Fred,

     The product detector is kind of required for the
locally injected carrier which is strong and stable.
The recieved carrier is either fading (AM) or absent
(SSB). As long as the Local carrier can be phase locked
to the recieved carrier the adapter will enjance the
AM audio signal. Seems it takes less carrier to phase
lock a PLL than it does to properly demodulate an AM
sideband. Hence the need for product detector.(s)

     On SSB the AFC is shut off to allow just the use
of the product detecter.(s) which is/was the point for
the CV 591 and the CV-157. The CV 591 does not suport
phase lock to the recieved carrier therefor is esentially
an external product detector relying on the stability
of the RX involved. With the CV-157 you can choose to
use the Recieved carrier or the Local carrier for
demodulation.

     I assumed you were looking for the "Ultimate"
AM detector for HI-FI reception. If you just want to
copy SSB cleaner any of the above mentioned devices will
work fine. 

     Clear as Mud, right?

/Dan

Yes always dreaming for the ultimate in receiving. The HC10 is this dream or was there another box?
I follow your thoughts about the fading carrier, but the HC10 only needs to lock-in to the on-air freq and the rest is the magic.
My SDR and a 1987 Kenwood TS440 take care of the SSB. The 390A is for AM mode QSO's and music listening on shortwave.
Fred

[N8ETQ]

Hey Fred,

        Yup, the only real diff then would be the lose of the Noise
limiter in the 390 when you don't use it's audio output. That is pretty
much compensated for by the strapping local carrier generated by
a synchronous detector setup like the sherwood box and others.

        Please let us know what you end up with.

Thanks

/Dan

[KE5YTV]

I have purchased a Hammarlund SPC-10 to use on my SP600. How would you rate it ?

[nq5t]

Good for SSB .. less so for AM when you don't need the additional selectivity offered by the HC-10.  And the 600 has better audio, even without using the diode load output

The only niggle I've had with one is that AGC can pull the 1st conversion oscillator a bit on strong signals causing a slight frequency "bobble" on the attack edge.  I added an input level pot to mine (a la the SPC-10) to try to tame this effect some.

That said, I sold mine several years ago but in retrospect I wish I hadn't  ...

Grant NQ5T

[flintstone mop]

Good for SSB .. less so for AM when you don't need the additional selectivity offered by the HC-10.  And the 600 has better audio, even without using the diode load output

The only niggle I've had with one is that AGC can pull the 1st conversion oscillator a bit on strong signals causing a slight frequency "bobble" on the attack edge.  I added an input level pot to mine (a la the SPC-10) to try to tame this effect some.

That said, I sold mine several years ago but in retrospect I wish I hadn't  ...

Grant NQ5T

Welp......this reply tells me everything.
To cut to the chase; I am interested in Hi-Fi AM demodulation. I'm not looking for selectivity or SSB capabilities.
The Diode load on the R390A is about all I can expect for hi-fi. And my Flex Radio and its software for a Sync Detector are about all I can afford. I will now accept those characteristics for AM reception. The Sync detector in the Flex is somewhat effective for the selective fading distortion listening to music on shortwave. The Sherwood was supposed to be the ultimate listening experience for shortwave.
I was thankful to receive an earlier attempt to copy the Sony 2010 Sync detector that everyone was raving about. After listening closely to the lack of low end bass in the music ( sounded like 100 hz was the limit) , I figured it was not what I was looking for, after all. The selective fading distortion was only reduced, as in the Flex Radio software; not eliminated as it apparently is in the Sherwood unit.
Sherwood went "tits-up" and those remaining units and the ones showing up on ePay will now increase in price cuz they are "vintage and no longer available".
Thanks for the replies
Fred