KPA1500 Questions + RFE

[Elecraft mailing list]

Dear Brain Trust:
1)  Is there a downside to using a very long FAN DWELL TIME, other than noise?  I am trying to get my amp to run cooler.
2)  Does anyone offer a KX3 to KPA1500 serial cable, and a K2 to KPA1500 serial cable for sale?  No, I can no longer build them myself, even though they are simple.
3)  Is there a way to command via macros the KPA1500 to run the fans at normal speed + 1 as the amp starts to heat?  Can this choice be implemented in firmware?

73, Eric WD6DBM
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[ANDY DURBIN]

"Is there a downside to using a very long FAN DWELL TIME, other than noise?  I am trying to get my amp to run cooler."

Your question seems to imply that you believe increased dwell will make the KPA1500 run cooler.  I wonder if you have any test data that supports that assumption.  My testing of my KPA500 showed no significant advantage to pre-cool or increased dwell but I don't claim to have explored all possible operating conditions.  I suspect that the most effective way to reduce temperature will be to lower the fan speed temperature set points.  There is a trade-off between temperature and noise.  The recent increase in the KPA1500 fan setpoints seems to suggest that Elecraft has chosen to reduce noise.

Yes, there is a downside to very long fan dwell time.  The fans will run longer and therefore wear out quicker.  Why do it unless you have data that shows some advantage?   "FANticipator" may help:  - https://tinyurl.com/y4tw92zz.

Andy, k3wyc
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[Bob Wilson, N6TV]

On Wed, Jul 22, 2020 at 7:51 PM eric norris via Elecraft <
[hidden email]> wrote:

> 2)  Does anyone offer a KX3 to KPA1500 serial cable, and a K2 to KPA1500
> serial cable for sale?  No, I can no longer build them myself, even though
> they are simple.
>

My Serial Box (S-BOX <https://bit.ly/S-BOX> or S-BOX-USB) can provide both
a computer interface to the K2 or KX3 for logging software (including
computer-generated CW and PTT keying over the same cable).  *Plus*, it can
also provides a parallel RS-232 connection to the KPA1500 XCVR SERIAL port,
all using standard stereo cables (3.5mm TRS to dual RCA-M) and a
KXSER-compatible cable (DE9-F to 3.5mm TRS) , all of which which I'll be
happy to supply with the S-BOX or S-BOX-USB.  The same scheme can work with
the KPA500.  Placing the amplifier in "no poll" mode means the logging
program must be responsible for polling the radio for frequency data,
instead of the amplifier.  No polling, no tracking (except by "RF sense").

If you have no need to control the KX3 or send CW by computer, and just
want the amp. to poll and track the KX3, then building your own 3.5mm TRS
crossover cable would be the most economical solution.

Connection of the KIO2 connector of a K2 to the KPA1500 through the S-BOX
is also possible with a standard RS-232 cable as long as the "PC" connector
on the S-BOX is not used (which would connect too many lines to the KIO2
DE-9 connector).  One of the S-BOX secondary DE-9F connectors (or
builtin-in FTDI USB-to-Serial adapters) can be used instead to just connect
the TXD, RXD, and Ground pins to the KIO2, leaving the others open.

I don't know if the KIO2 AUXBUS line (pin 6) is compatible with the KPA1500
AUXBUS line (pin 2), but if so, this connection is also possible through
the S-BOX's 15-pin connector and a 15-pin M/F cable, which I can also
supply.  I don't know if the ACC2 AUXBUS option on a KX3 is compatible with
the KPA1500 AUXBUS.

73,
Bob, N6TV
https://bit.ly/S-BOX
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