N9EWO Review :
Ten-Tec RX-340 DSP HF Receiver

This 2001 sample of Ten-Tec’s RX-340 had a properly made MAIN florescent display.
A later tested 2005 sample did not fare well in that area (see text and picture below).
In our testing it did NOT equal the WJ-8711A for very weak signal recovery.
(Photo : N9EWO)

I do NOT own a Ten-Tec RX-340. Test samples were used for the text below.

Serial Numbers: 2001 Sample 1015x, 2005 Sample 1038x
Tested Firmware Version: (All 3 EPROMS, both samples) 1.10A
Country of Manufacture: U.S.A.

No Wasted Space / Outer Cabinet Strongly Advised

I was most impressed here with the cabinet. Tec-Tec did excellent job here. It's of heavy gauge aluminum that is all of an "anodized" nature. This might not be much of an issue, as many purchasers will go for an optional cabinet of some kind.

Ten-Tec no longer offers a METAL tabletop outer cabinet (just a strange looking wood one). A cabinet is strongly advised too, as if you by accident (like I did) catch your hand or arm on the "very sharp" ears of the 340's front panel, you can take a nice gouge out of your skin. Ten-Tec does include 4 rubber feet with screws to do "quickie" desktop mounting.

Hammond Manufacturing offers nice after market tabletop STEEL cabinets in a Gray color with close depth of the receivers cabinet. At one time Ten-Tec did offer an aluminum cabinet (# 19-0525), but it was way too deep at 18.4 inches, and when mounted in this cabinet the owner had to stick a hand a good ways in to access connections of the actual rear panel. Awful it was.

Front Panel "Sticker" Not Stuck So Well

The front panel is too made of aluminum, but is of course much thicker. Just as the WJ-8711A is, we have a large plastic "Stick On" decal that contains the pretty side of the set including the control markings and all of the panel lenses. However, on the first test sample in the strip area just above the main display to the top edge, the sticker was not sticking very well, more like hardly at all. Was lifted right up. Pushing it back down with your fingers was to no avail, because in just a few min's it was lifting right back up again.

Not good on a over $4000. product. I'm assuming that the adhesive on this sticker is failing due to just enough heat that the entire cabinet gives off, that makes the decal not stick?? This was never a problem with any of the WJ's (HF1000A or WJ8711A) I have owned. However with the second test sample this was not an issue.

Nice Quiet Switching Power Supply / Set runs generally just warm

We have a nice quiet internal "Chinese" Philhong switching power supply in the RX-340, (PSA4541 model) with of course a 3-wire plug and socket. No excessive RF buzzes, and no strange noises being emitted into the room (i.e.: JRC NRD-301A or NRD-93). Just a nice quiet little switching power supply that does not run overly hot. But I would not block the top or bottom panels, keep it open so the air can flow and you should never have a problem here. The set has air vent holes on the top and bottom.

The entire set does not run really hot, a bit warm I would say. But it certainly does run a bit warmer than the WJ 8711A, which really runs almost cold in comparison.

Excellent keypad and function buttons / Excellent main optical "Tuning" encoder / "Aux parameter" and "Memory Scan" knobs but touchy to adjust.

Robust factor of all of the front panel keys and buttons are well above average. Not to say the failure rate is going to be any better as they are using the "tact" variety type switch, which is the same as what JRC is using in the NRD-545. But being that the "hit" point of these switches is so good, that this will certainly have add to a longer service life, than being hit say at a wrong angle.

Main tuning knob is a real treat. Of course it is using an optical type encoder. But it has a fantastic "smooth" feel with no play or restriction whatsoever in any direction. Ten-Tec went with an
"Oak Grigsby-ElectroSwitch" high quality optical encoder for the tuning knob and did it right. Properly weighted-rubber track knob as well.

The other 2 encoders being used for the "Aux Parameter" & "Memory Scan" knobs (made by HP) have a OK feel, however the only fly in the pudding with these 2 controls is that they are very "fiddly" to fine-adjust as they have no indents. You sometimes find yourself playing with this longer than you should be having to, for example when you are setting the PBT to zero finding "0" can be a game. Can be a real pain. You can however use the keypad to set the PBT (and other functions) to "0" as well and this somewhat makes up for this.

Tuning Knob Tension can get as free as one can ever get it.

There is a way to adjust the tuning knob “flywheel” tension.

While holding onto the main knob, one then turns the silver ring part of the knob and you will feel clicks and allows for adjustment. May turn out to be a bit tricky for people with less than thin fingers.

But I was able to get it so loose where I could literally give it a spin and let it go and have it tune from one end of it’s range to the other without touching it again. Almost looked like it was motor driven it was that free.

Excellent Ergonomics - Except For Memory Operations / Scratch pad Memory

The great buttons / knobs help very much with the feel of the set, but the ergonomics are also very good to my liking. The "merry-go-around" mode selection is a bit of a set back, but that is minor.

Only real downfall on the ergonomics is with memory recall and storage. It takes more thought, presses of pushbuttons to get what on the WJ would only take one press. I like the memory layout MUCH better on the WJ.

Ten-Tec did indeed add more memories from the original version with started out at 100. It was increased to 200 later on. But I found 100 on the WJ to be most adequate and much less confusing.

I do like the scratch pad memory found on the Ten-Tec, that is indeed handy, but again it makes the whole process of memories even more confusing.

Memories do not store "Tuning Steps", but will store SAM status.

Super Good Quality Volume Control / Really Poor Headphone Control and Output.

Volume Control is of above average quality has a great feel and movement. The control for the headphone level was a completely different story however on the tested sample. First the level that is available at the headphone jack is grossly inadequate, even turned up to full rotation is wimpy.

But wait a second, better not turn up the control all the way either. On the first tested sample the right channel of the stereo headphones dropped out when fully rotated. Moved it a pinch back counterclockwise and it came back. Also the feel of this "headphone" control was poor to me. Could just be a sample thing here, but the level of the headphone output is an issue that needs to be looked into for sure.

UPDATE : Stereo Headphone Volume Control still continues to be of Low Quality, and still lacking output as well.

With the first sample we had an issue with the “Headphone” volume control cutting out when fully rotated. Well with sample number 2 (2005) this was found be an even greater problem. This time in two spots (when 32 ohm stereo headphones were used), one near normal “lower” volume level area and again at near full clockwise rotation, the output cut out in one channel. This was very annoying and unacceptable.

Also the headphone level also continues to be a bit on the low side. This will not be a problem with properly modulated signals, but if it’s on the weak or weaker side...then “we have a problem Houston”.

Display "Dimmer" / Main Display a Bit Brighter On Right End On Test Sample / Meter Light Too Dim - when Florescent Displays Are At Good Level. / Display Bug-A-Boo on 2005 2nd Test Sample.

The Ten-Tec RX-340 has 3 blue "Florescent" displays. 1 of course being a longer alpha type that displays the frequency, mode and tuning step. It also gives feedback for the "Built In Test Equipment" (BYTE). Sorry to say no alpha tags for the memories, but with professional sets like this...you really cannot expect this. The other 2 are smaller and made up of dots. Probably these smaller are not quite as big as the WJ's, but OK size.

But what is a requirement for florescent displays like this is a "dimmer" control. And boy does the RX-340 need one. Thank goodness it can be found, but is a bit elusive. It is covered in the owners manual. Pushing and holding the "setup" button and rotating the "Memory Scan" knob allows for just about any brightness you want, even "almost" off. If it was not for this, you would need a pair of sunglasses or a bottle of aspirins as it is way too bright at 100% and would give someone a good headache in short order.

I did notice on 1st test sample that the main (large) display, towards the right side tends to be a touch brighter than the rest of it. It's not something of a real nasty level but nevertheless is a problem that I must comment on (It bothers me). The other 2 smaller dot-displays have no such of a problem.

There is a little gremlin with the "Dimmer" function. The meter lighting is also tied into the same dimmer circuit as the florescent displays. With the florescent displays set a good level say at 20%, the meter lighting is so dim at this level to be worthless.

S-Meter is nice and huge with markings that give the standard S-units for most nonprofessional types along with dbm. It has been reported that the lamp in this meter can and does burn out fairly easy and is not a easy chore to replace (direct wired inside the meter). Note: Later production samples now use LED meter lighting (untested).

The main larger fluorescent display and associated electronics with this display are made by Samsung in Korea.

As can be the case with fluorescent displays when quality control is lacking, the 2nd test sample large main display while operating properly, had inconsistent lighting in each of it’s segments (of each digit). See the picture below. This issue varies with intensity level, and is even more noticeable when you reduce the brightness. Really should a $ 4000. receiver have this bug at all (and the answer is a STRONG NO !!).

More I looked at this MAJOR display flaw, the more I hated this receiver entirely !

The other 2 smaller displays were just fine with no issues unlike with the main larger one.

Unacceptable "Main" Display with the RX-340's 2005 2nd sample we tested.
Uneven lit segments with this Samsung made display.
The first 2001 sample never had this gremlin
(photo : N9EWO)

Tunes and Displays 1 Hz Increments, "Rock" stable.

As it should be on a professional set of this caliber, we have 1 hz increments that are tuned and displayed. Set's display seems to be very accurate as well at least within 1 hz, even at 15 MHz and above. The TCXO is rated only at 1 ppm , most commercial receivers are rated at bit better than this. But it seems to be rock stable in any event. By the way , the WJ8711A is rated at .7 PPM as standard.

There is a 9 kHz tuning step (very early versions lacked this).

Audio Recovery Excellent / Excellent Sensitivity-Selectivity ,"But....." / SAM Has Selectable Sideband / Breathtaking Manual ECSS with Fantastic PBT .

Audio recovery, that is pulling the spoken work from out under the noise and static form a weak broadcast station, is way above average on this set. But this is where the Watkins Johnson WJ8711A wins (using manual ECSS using the USB or LSB modes). We are not talking about a huge difference here, but it does have to edge to my ears when signals get super weak. This more than likely has something to do with the improved sensitivity that the WJ8711A has. Also from test numbers elsewhere, the WJ has much improved "close in" dynamic range. This is indeed noticed when you are trying to listen to weak station as it sits next to a stronger one, the WJ rules here...no contest.

Again to achive the excellent audio recovery one must use manual ECSS (USB or LSB).Manual ECSS is simply breathtaking, and works very well indeed. All SSB modes are extremely clean along with fantastic PBT performance makes for a winning combination in this area.

The RX-340 does have selectable sideband when using the SAM mode, but it's sort of weird how they achieve this. You switch to SAM, then using the audio select button, which is normally used for ISB operation, that is the “LSB-Both-USB” button is used to select the sideband desired. The PBT button still will not function in the SAM or ISB modes, which is a huge drawback. Notch still is inoperable in SAM, AM and ISB mode as well. Yipps !!

SAM works with bandwidths up to 16 kHz, (very early samples did not) but is still limited as it will not work with filter selections below 4 kHz.

Sync AM (SAM) Generally Clean But Is Just About Worthless.

MAJOR downside with the SAM is that it is a very poor performer. It cannot lock onto a weaker signal , but even was an issue with strong totally in the the clear signals as well. If it's sort in the middle, a 50-50 sort of thing. Might be ok, or it might not. Has to be tried on a signal-by-signal basis. If it fails to lock right...then of course switch to Manual ECSS where you will do much better and with PBT control to boot.

It’s not even in the same league with other sets including the double sideband SAM in the WJ-8711A. The WJ's SAM hold lock quite well..

Overall audio quality is really excellent on the RX-340 (aside from the low headphone output), perfect for DX'ing the weak signals as well as strong broadcast audio. No excessive hiss and not overly bassy either. But the "Buzzy-Crackle-Tick" sound that is explained below takes away a bit of this "great audio".

Another Downside With SAM / AM and ISB, Weird "Buzzy-Crackle-Tick" Sounds

Where as the
JRC NRD-545 has its "Pop-Pop/Tick-Tick", and "Burp" sounds, the Ten-Tec has it's what I have to call "Buzzy-Crackle-Tick" sounds (usually not all at the same time). And also like the JRC, this does not show up all the time, and for many may not even be able detect it as most of the time this noise lies within the floor of the audio (but not always). I only noticed this when using SAM, sometimes in unvarnished AM, but worse when using SAM and having selectable sideband engaged (LSB or USB and not when in the middle "both").

But really shows it's ugly head when in ISB mode. Adjusting the AGC a bit might help, but not always. This is not what you might think, say the SAM switching in and out (unlocking as it does more than not), as the SAM is solidly locked when this sound does appear.

This a weird sound and might take awhile (or maybe never) to detect it. I'm guessing that it's another case of the DSP getting overloaded but not sure??

Aside from this problem the internal speaker can indeed create it's own (other) buzzes under the correct audio frequencies and volume (cabinet just resonates here), so best to use a external speaker. Also it uses a nice standard 1/4 phone jack (mono) for a external speaker connection.

"Running Out Of Volume Control"

As commented earlier the headphone output is lacking big time, but this one is a totally different animal. It is a dead ringer to the same problem that plagues the JRC NRD-545 and NRD-301A sets. But is not quite as bad in the RX-340.

Once in awhile you will encounter a broadcasting station where the modulation is below par (low). It's a common event as you tune across the bands, sooner or later you will come across one. When this comes about you will struggle to get enough volume even at 100% rotation. Like it needs another 50% rotation to achieve any kind of proper audio. Well you don't have it and you are stuck having to try and hear a strong carrier but with hardly any good level audio.

Switching over to manual ECSS with a narrower might help a bit in this regard, but not always. As you can figure out already, with the low headphone volume issue, you might as well forget trying to use headphones on a signal like this.

Another gremlin that the WJ-8711A does not have period. The WJ's audio can blow you out of the room.

Audio "Line" in Stereo Balanced or Mono Unbalanced Outputs, DB 15 Plug Extra Cost.

The Ten-Tec RX-340 has a selection a line outputs that permits the user to choose what suits the situation. That is either a "Balanced" 600 Line (with transformer isolation), identical to the WJ. Or and more important to us consumer types, an UNBALANCED 600 Ohm output. This unbalanced output is in mono, so proper connections to consumer equipment without any weird transformers or such.

However, NOT SO FAST!!! The small gremlin is that Ten-Tec does not include the proper DB-15 connector plug. The owner must purchase this separate. A silly oversight, on a set of this dollar value it really should come with the set in the box!

Good Noise Blanker / Preselector Standard / Built in Test Equipment (BITE), But Wait 1 Hour

There is an adjustable noise blanker function (also lacked on very early versions), and works well.

A built in half octave front end preselector is included as standard

Just as with the WJ sets, we have BITE (Built In Test Equipment). Here was news that I was unware of. This text WAS posted up on the Tec Tec Web site at one time.

"The RX-340 must be at room temperature (on for about 1 hour) before BITE test is performed. Antenna and headphones must be removed before performing the BITE test. BITE test will fail if antenna or headphones are attached."

Standard Serial Cable Will Not Work

For anyone who might desire computer control of the RX-340, one needs to read the text on page 5-1 in the owner’s manual.

“Important Note: A standard serial cable will not work. An interface cable for the RX-340 must use pins 2, 3 and 7 only. Other pins on the DB-25 connector carry DSP data.”

So it appears that the owner will have to roll their own instead of purchasing any commercially made standard cable.

Not as Good as the WJ-8711A To Me, But Lower Cost

Even with the TenTec RX-340 using an outdated 16-bit DSP (along with 16 bit A/D-D/A converters as well), it still has the right stuff to make it an attractive set for the person willing to spend over $4000 to acquire such a premium receiver.

I generally liked this radio, even with the weird warts attached. However, with the 2nd sample that had the unacceptable main display issue made it a MUCH less desirable product to me.

Yes, you guessed it......I still
much prefer the WJ-8711A to the TenTec RX-340 (used market).

Dave N9EWO
Ver. 3.8

Universal Radio's RX-340 Web Page

Donald Nelson - Aug 2000 RX-340 Initial Report

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