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Author Topic: TX-500  (Read 335 times)

KN6SU

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TX-500
« on: February 28, 2021, 05:37:07 PM »

Well, after months of waiting while it was back ordered, I finally got the Lab 599 TX-500 all mode HF-50 MHz transceiver, which is very light weight (just over 19 oz) and ruggedly built. After a quick review of the manual I took it out for a spin today in my back yard just long enough to make sure I knew how to use the controls and make one SSB contact to get an audio signal report from a local (<75 miles) on 20M. Considering the late afternoon band conditions and quick set-up portable antenna I was using the audio report was quite good. Reception across the band was also good due to the excellent filtering, which was quite easy to control. In fact all of the variable radio transmit and receive parameters are easily and quickly accessed by a very few button presses and main dial turning. The menu embedded menu was very well thought out by Lab 599.

I'll have more to say about this rig as I put it to use, but so far  I am favorably impressed, except for one thing. While tuning the VFO across the bands I got a few annoying transient audio "pops" while passing (in either direction) across certain frequencies (e.g. there are two on 20M at 14063 and 14336). I thought I had a defective unit and emailed Lab 599 support to ask them about this (I sent a video file demonstrating the phenomenon). They got right to me and explained these were spurs due to their SDR circuitry and are "normal" in that design. The pops don't seem to affect performance, but I would have thought Lab 599 could have been able to design the radio, especially since spurious emissions are a well known problem in SDR architecture, especially in things like DC-DC converter circuitry.  Since these spurs really don't seem to otherwise affect receiver or transmitter performance, I'm willing to live with them. The lightning quick response from Lab 599 is also reassuring.
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KN6SU

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Re: TX-500
« Reply #1 on: March 01, 2021, 06:51:31 AM »

I should have mentioned that Lab 599 did explain that the spurs (which really are just a minor annoyance) are a consequence of the SDR sampling method which was chosen to be extremely energy efficient (which this rig certainly is), and in fact the internal components and circuits are very well shielded and isolated.

My IC-705 doesn't disturb me with any audio spurs, but it's also rather large and overweight and fragile in comparison to the TX-500. I'd prefer to take the 705 on a pleasant day hike or extended well-provisioned camping trip (where weight and bulk are less of a concern), but prefer the TX-500 for any real backpacking or mountaineering.
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VK6HP

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Re: TX-500
« Reply #2 on: March 02, 2021, 06:38:25 AM »

It'll be interesting to hear how you get on with the TX-500.  As it happens, I'm currently playing with a friend's radio, and today updated it to V1.05.00 firmware, which I'd recommend.  I also had his IC-705 for a short time and I'd agree that the form factor of the TX-500 is preferable: a desk tripod never worked for me with the IC-705 and I ended up supporting it with a therapeutic heat pack in a kind of mini beanbag arrangement.  The TX-500 is nicely made, and I particularly like the locking circular connectors.  The screen of the IC-705 is vastly more impressive but the TX-500 band display is just about good enough to be useful.

The biggest problem I had was adjusting the mic gain and compressor to get decent audio and good ALC action.  In particular, it was easy to generate leading edge transients, viewing the SSB envelope with a digital station monitor.  With care I managed to get it respectable and I suspect that the new firmware has also helped although I haven't yet verified that. I've yet to look at the CW operation closely.

Neither radio supports LF/MF operation well, although the IC-705 receiver does tune the 2200 and 630 m bands.  The TX-500 is also missing an internal soundcard, of course.  Either radio with an LF/MF low-level transmit drive signal would be a winner in my particular application.  Both receivers were lacking somewhat in dynamic range when used in an A/B comparison with my TS-890S, but I'd expect that.  I didn't notice the TX-500 receiver spurs too much, especially in actual operation as opposed to tuning around with the dummy load connected. 

I don't know about the menus: I'd say both the IC-705 and TX-500 are passable without being distinguished, although I mildly preferred the ICOM implementation.  Perhaps that's just a function of a little familiarity with some of their other radios.

My general impression is that the TX-500 is well constructed and, despite a few rough edges, puts in a credible performance which will likely be refined as more units are sold and operated. The radio's owner also mentioned the excellent manufacturer responsiveness in helping to sort out some minor issues.

73, Peter.
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W1VT

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Re: TX-500
« Reply #3 on: March 02, 2021, 06:54:19 AM »

It is hard to beat the tuning feel of well designed analog VFO controlled rig.
But, building one that is stable and tunes smoothly without backlash takes a lot of skill. 

Back when the HW-9 was popular I got an on the air comment that my rig was the only one that didn't drift.

Zak W1VT
« Last Edit: March 02, 2021, 07:03:17 AM by W1VT »
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