[Elecraft] [KPA500] - 144MHz Version?

[Lew Phelps K6LMP]

If a 2-meter version of the KPA500 ever gets to the drawing-board stage,
I'd vote for two-band capability, adding 6 meters; this would be ideal
for VHF/UHF contesting, as it would provide a single amp for the two most-used 
bands in those contests. I think that trying to stretch it to 432 mhz would
be a much more difficult design challenge, since it would require more 
modification to the circuitry than substituting a different power transistor,
whereas you might be able to accommodate 2 meters with the existing board layout
or something similar.

Lew K6LMP


On Sep 6, 2011, at 7:48 AM, Allan G Duncan wrote:

> I was recently studying the schematics of the KPA500 and looked at the
> specification of the VRF2933 devices which are used in the RF deck of the
> amplifier. I noted that the devices are rated to 150MHz which made  me think
> a 144Mhz version of the KPA500 would be a nice addition for a K3 equipped
> with a K144XV 2m option (or indeed any 144MHz transceiver). Nearly all the
> existing KPA500 metalwork, PSU and front panel PCB (with different firmware
> and no band buttons) could be carried over with a different RF deck (perhaps
> using the same VRF2933 devices and heatsink). A 2m version could potentially
> be lower cost as the switchable complex LPF arrangement of the HF/6M KPA500
> would not be required. The RF deck aside, the R&D costs would be low, using
> much of the already proven KPA500 hardware. The 500W output is ideal for
> here in the UK where the power limit is 400W. Even a 432Mhz version could be
> created although the VRF2933 devices would have to be replaced with
> something else - I suspect the demand for this 70cm version would be far
> lower than that for 144MHz and would not be cost effective for Elecraft.
> 
> I currently use a Henry Tempo 2002 using two Eimac 8874 on 144MHz. I think
> that a 144MHz KPA500 would be cheaper than obtaining two replacement tubes
> for my existing amp! I would certainly be very interested in the purchase of
> a 144MHz KPA500 (KPAV500 ?) - anyone else?
> 
> On a slightly different matter, I note that the KPA500 front panel PCB
> schematic also has an unused "2nd RF deck" connection - perhaps for a future
> KPA1000 utilising two of the KPA500 modules combined?
> 
> 73
> 
> Allan
> GM4ZUK
> 
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