Re: PA problem on new QRSS TX, some progress ;-)
|
No problem Andy, My kit is using just the 2 x BS170 at 5v. That is giving 50mw 73's Andy GJ7RWT
From: "andyfoad@..."
To: QRPLabs@...
Sent: Friday, May 17, 2013 5:42 PM
Subject: [QRPLabs] Re: PA problem on new QRSS TX, some progress ;-)
?
Right then lads...Andy & Eddie,
Just done the DDS pot tweek and it sprang to life on 28Mhz!
Not done exhaustive tests yet but at least it's looking like
the RF from the DDS is being amplified by the 4 x BS170's at 9 volts.
Andy Cutland <gj7rwt@...> wrote:
> Yes I've adjusted the blue pot so that the unit functions on 10m
> but have not adjusted it for max power as the lower bands suffer.
Not had a chance to try it myself but thanks for bringing that up.
Good to know.
> I am at a sort of half way house. I've been getting a few spots on
> 10m wspr today, the best being 4x1rf at 3.5k km so thats good
> for 50mw out into a random wire.
50mw. Well that stacks up with my crude finger on the 50R resistor
tests so far ;-) I.E. not much heat being generated. Well at least
it initially looks like we're seeing the same results.
I just stuffed the TX on 21Mhz via the 28Mhz LPF and that seemed
quite warm. I dunno what the S11 of the LPF is at 21Mhz or it's
response curve so there may be losses and unrepresentative.
Frankly I'm surprised that the BS170's have enough gain do work
at the higher freqs, so I'm not complaining.
Off now to build a 17m LPF and then the rest after some more tests.
Looks like this is going to be a fruitful weekend.
Thanks Eddie and Andy for you observations and contribution to this
thread.
Anyone got any confirmed power output figures yet on 28Mhz ?
73 de Andy G0FTD
|
