[hpsdr] PennyWhistle Comment Summary

[Graham / KE9H]

Todd:

Even though the VHF transistors are rated at 15 watts, and the HF
transistors are rated at 16 watts, I saw what appeared to be an
overall increase in power output at all bands of about 1/2  to 1 watt.

The suggestion to switch was based on a reported highly variable
unit-to-unit variance in 6 Meters performance when using the
HF transistors.  I haven't built enough amplifiers to see that,
but it is certainly a reasonable suggestion.

I have PC boards in hand with the changes requested by the
group, and am starting verification tests now.

--- Graham / KE9H

==

Todd Mondragon wrote:
> How did the VHF transistor experiment turn out for you?
>
> 2009/2/16 Graham / KE9H <KE9H at austin.rr.com <mailto:KE9H at austin.rr.com>>
>
>     ***** High Performance Software Defined Radio Discussion List *****
>
>     All:
>
>     Thanks to all that took the time to comment.
>     I have summarized the comments below
>
>     Connectors:
>     Extremely strong support for BNC rather than SMA.
>     For those who wanted direct wire attach, you can easily do
>     that with either a BNC or SMA footprint. Center to center,
>     and shield to any ground via of your choice.
>
>     Surface mount parts:
>     The majority of the group seemed quite comfortable building this
>     level of surface mount kit.  There are only about two dozen
>     surface mount parts.
>     The SMT part size is the largest common size, that is, 1206 for
>     caps and resistors.
>
>     Regarding the switching relay, majority said "keep it simple."
>     I will provide the capacitor values for both the tuning
>     points of 30 MHz and 50 MHz peaking, so the builder can do
>     as he pleases.
>
>     The option will be provided for an extra feedback turn
>     on the balancing transformer, for those that want to dump
>     some gain (and lower power output), and increase linearity
>     for driving another linear.  
>     Regarding substituting some VHF transistors for the HF
>     transistors for more consistent output at 6 Meters.
>     I have ordered and received some of the VHF transistors.
>     I'll install them this week and see what it looks like.
>     The footprint is identical to the HF transistor, so no
>     matter what the outcome, it should not affect the board
>     layout.
>
>     --- Graham
>     <http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/>
>

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