Mike, The TXDVGA in the radio goes into clip at around +7 to +8dBm on two meters. More power output is available on HF -- around +16 to +17dBm. You should be able to safely plan on always having +5dBm on two meters and this will give you a little margin. They are not walking around by more than 1dBm or so.
Steve Steve Stephen Hicks, N5AC VP Engineering FlexRadio Systems™ 4616 W Howard Ln Ste 1-150 Austin, TX 78728 Phone: 512-535-4713 x205 Email: [email protected] Web: www.flexradio.com Click Here for PGP Public Key<https://sites.google.com/a/flex-radio.com/pgp-public-keys/n5ac> *Tune In Excitement™* PowerSDR™ is a trademark of FlexRadio Systems On Tue, Jul 9, 2013 at 8:45 AM, Mike Valentine <[email protected]> wrote: > Here's a cross post of mine from the FlexRadioSmartSDR Yahoo group: > > I've been mulling over the same question. > > One needs between 40 and 50dB of gain to get to 25 or 50 watts (44 to 47 > dBm) output. I'm waiting to find out just how much output one can expect > from the 6700 transverter transmit port on 2 meters. The documentation > says 0 to +10 dBm, max. I want to find out whether this figure varies from > one 6700 to another as well as how much it may differ between the 0-77 MHz > configuration and the 135-165 MHz selection, let alone variations in each > segment. > > Being conservative, let's assume 0 dBm is the max that comes out of the > transverter port on 2 meters. I looked at the DownEast Microwave 2 meter, > 30 watt amplifier, the 2M30PA. Its specifications say it requires +10 dBm, > typical, and +14 dBm (25 mW) saturated, drive power. Clearly, the 6700 > won't drive it to saturated output. The question is, "How far will it > drive it?" > > It's likely that an interstage amplifier (post-amp?) with 10 to 15 dB gain > will be required to boost the 6700 2 meter output up to the point where an > amateur-market device will serve as a useful "barefoot" transmitter. > > Some folks (like me) want to drive an EME amplifier directly with the 6700 > without going through a 28 MHz IF transverter. I like the idea of very > clean transmit characteristics (phase noise, for one) when running 1 KW > near other 2 meter contesters. 50 watts seems like the right target output > power to serve most needs. > > Here's what I am likely to chose among: > > 1) Spend WAY too much money and purchase a Mini-Circuits ZHL-100-52+< > http://www.minicircuits.com/pdfs/ZHL-50W-52.pdf> instrumentation > amplifier that could be used for 2M, 222, and 432 with appropriate output > filters. It has 50 dB of gain (47 dB min.), but has an absolute maximum > drive limit of +2.0 dBm. It might need a safety pad on the input if the > 6700 has more than that amount of drive available. > > This method requires the least amount of ingenuity and/or engineering > work, but is very expensive, not comfortably robust, requires a 24V power > supply, and still needs lots of T/R switching, etc. > > 2) Spend less money and buy a W6PQL 80 watt 2 Meter amplifier kit that > uses an SAV36 power module. < > http://www.w6pql.com/2_meter_80w_all_mode_amplifier.htm> > > It needs +17 dBm of drive, so 20 dB of gain and a 1 dB compression output > of +20 dBm seems right for a post-amp leaving the 6700. > > The post-amp might be a Mini-Circuits ZHL-2500VH+< > http://www.minicircuits.com/pdfs/ZFL-2500VH+.pdf> . It has 18.5 - 21.5 > dB of gain and a 1 dB compression power of 200 mW (+23 dBm). It can also > tolerate +10 dBm of drive with no damage. It can run from 13.6 Volts and > costs more than double the W6PQL kit, but it comes ready to go. > > 3) Purchase a DownEast Microwave L144-28HP 60 watt output transverter< > http://www.downeastmicrowave.com/PDF/Manuals/L144-28rB.PDF> and > "weird-wire" its guts to eliminate (disconnect or remove) the LO and mixer > sections. > > I propose to use only the low-level transmit chain amplifiers all the way > through to the PA module. The 6700 transverter output would connect where > C44 feeds the IC3 (MAR3) transmit pre-driver. I would remove C44 from the > circuit-board and feed a coax (reconnect C44 in series) to the input of > IC3. The other end of this coax would go to where I propose to remove C90 > and connect to the junction of R35 and R36, the output of the TXIF > adjustable pad. This pad works well enough at 10 meters and will probably > work just fine at 2 meters if one isn't terribly choosy about perfect VSWR. > > I propose similar messing about with the receive pre-amp sections to > provide a really great pre-amp with at least 2 dB better noise figure than > the internal 6700 135-165 front-end pre-amp. Details to be easily worked > out. > > This option uses high quality, robust components in the both the transmit > and receive signal chains, includes T/R switching, and runs from standard > 14V power supplies. Plus, if one ever tires of this way of doing things, > it can be put back to a useful condition with reasonable value at resale. > > END OF LIST! > > If anyone else has an idea or two, please let me know. > > Cheers, > > Mike - W8MM - EM79sd > > > --- In [email protected]<mailto: > [email protected]>, "DrPaper" wrote: > > > > The output of the 6700 is 0 dbm or 1 mW on 2 meters > > > > Anyone have any suggestions for an amplifier to raise the power levels > to something useful? > > > > > _______________________________________________ > Flexedge mailing list > [email protected] > http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz > This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is > used for posting topics related to SDR software innovation and other > technical SDR topics. > _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software innovation and other technical SDR topics.
