> I'm not sure that I understand Joe's (W4TV) comments regarding the
> antenna issues when operating SO2R, but that's probably because I
> don't work contests.
Instead of providing two sets of antenna ports and routing the "second"
(unselected) exciter around the amplifier, the Expert-1K and 2K both
switch the "second" radio to a single "SO2R Antenna" port. Since there
is no band switching on the "SO2R" port, that limits the second radio
antenna(s) to a generic multi-band antenna or a *separate set* of
manually selected antennas.
Serious SO2R contest operators generally prefer to have optimized
antennas connected to both radios at all times.
73,
... Joe, W4TV
On 4/25/2012 12:04 PM, Joe Giacobello, K2XX wrote:
> I've owned the 2K-FA since about the first week of 2012. So far, I'm
> quite happy with it. It replaced a TenTec Titan 425 and a Command
> VHF-1200. I was getting ready to contribute a write-up on it for the
> Contesting.com site, but I wanted to evaluate it for a few more weeks
> before doing so. Here are some initial assessments.
>
> 1.
>
> It easily puts out 1500W on all bands from 6-160M with about 30W
> drive. I have seen the output power go as high as 2,200W out on
> some bands when running it in MAX power mode and allowing the ALC to
> limit the drive. With 1500W out, you're limited to about 15 seconds
> or so key down and then it automatically switches to MID power
> mode. (Power was measured with a fairly recently calibrated LP-100A.)
>
> 2.
>
> Utilizing the ALC and maximum exciter drive (200W), as recommended
> by the manufacturer, in MID power mode, it puts out about 1,100W.
> The ALC action throttles the drive to about 40W. Presumably, the
> key down time under these conditions is quite long, since MID power
> is recommended for RTTY by the manufacturer.
>
> 3.
>
> The amp is set up for connections to two different exciters and band
> switching can be accomplished automatically through parallel
> connections to the exciters' serial ports or via the amps internal
> frequency counter. The manufacturer recommends using serial port
> switching rather than relying on the frequency counter. Having all
> switching done internally in the amp has really simplified and
> reduced the number of coax links and external manual switches in the
> shack. I think the exciters will also switch automatically with
> applied RF, but I've never tried it.
>
> 4.
>
> The amp has a port for connection to a Steppir control box for
> automatic band selection on their antennas. I haven't hooked this
> up yet.
>
> 5.
>
> I have run 200W through the amp in standby mode without any
> problems. However, because of the internal switching, the exciters
> are not connected to an antenna unless the amp is turned on.
>
> 6.
>
> In contrast to its predecessor, the 1K-FA, fan noise is barely
> noticeable.
>
> 7.
>
> The internal tuner seems to work as advertised, but I never use it
> since I have all resonant antennas or an external Matchbox.
>
> 8.
>
> The only serious problem I've had is that one of the six antenna
> ports doesn't work at all. The domestic distributor (Expert Amps
> USA) offered to fix it on the spot if I brought it with me to the
> Orlando Hamcation. But since I could live without one of the ports,
> I decided not to bother. In talking there with the owner and
> designer, Gianfranco I0JY, he thought it might be a relay. (It also
> might be a cable problem, but I haven't gotten in there to check.)
>
> 9.
>
> I don't operate RTTY or contests (seriously), so I've never seen the
> internal temperature exceed 50C. I believe that the amp shuts down
> if the temperature gets to 76C.
>
> 10.
>
> One problem that I have is that there is no service manual.
> Apparently, the manufacturer is concerned about protecting his
> design. (OTOH, it seems to me that it could be easily reverse
> engineered.) Nevertheless, the service guru is a W5 who shows up on
> the reflector to answers questions, etc.
>
> I'm not sure that I understand Joe's (W4TV) comments regarding the
> antenna issues when operating SO2R, but that's probably because I don't
> work contests.
>
> The bottom line is that with the exception of the antenna port problem,
> the unit has worked flawlessly so far.
>
> 73, Joe
> K2XX
>
>
> On 4/25/2012 9:57 AM, Paul Christensen wrote:
>>> I would also be concerned about cooling (and noise) with that much
>> dissipation in such a small box.
>>
>> I have the 1K version of the SPE amp. Nice, compact and reliable design.
>> If the League's QST product review is to believed, IMD performance is
>> excellent for a solid-state design.
>>
>> No contesting here but when using CW in say....a 2-3 minute exchange, the PA
>> deck becomes quite hot and the fans are running "full tilt," resulting in
>> what sounds like a jet engine. That, together with output power that
>> changes with PA deck temperature seems to be problematic with most
>> commercial solid-state amps. SPE does use a very well designed protection
>> system. In effect, a high-speed bus is created to kill bias to the PA
>> transistors when one of about a half-dozen faults occur.
>>
>> I like the amp for its instant-on, compact design, but I would never use it
>> as a replacement for a good VT amp. I saw the 2K amp recently at the
>> Orlando hamfest and for folks wanting a solid-state amp, I think it's worth
>> considering. But if noise in the shack is bothersome issue, ask other
>> owners about noise level with varying duty-cycle at full output power.
>>
>> I believe the 2K version has a vacuum relay option that adds several hundred
>> dollars to the purchase price. In my 1K, its T/R frame relays were way too
>> loud. I ended up modifying the amp's logic for use with an Ameritron QSK-5.
>> The interface between the two units is optically isolated and a schematic is
>> shown on my QRZ.com page. Much happier with this arrangement as it's fast,
>> silent, and no truncation of keyed elements.
>>
>> Paul, W9AC
>>
>>
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>>
>>
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