Adding RF Negative feedback to a complete exciter / linear system?

[w3jn]

That is, if you can figure out the TAPR web page, and figure out which modules are available anymore, and decipher what modules you actually need to make a working radio.  Oops - that ONE module you need is now no longer available 

[WA1GFZ]

TAPR is not in the HPSDR business. They do production runs when there is enough demand to make it worth doing. They try to unload all the stock as soon as possible to get their money back. Coming late requires one to wait for the next production run. A guy in germany has been dupilcating the open source hardware.  We waited 2 years for mercury to happen so join the club. I have found quality very good and everyone very helpful. There is some real software talent behind this stuff. TAPR doesn't release anything until it is right. The only design issue I have found was the temperature of the a/D on mercury. I glued a heat sink to the top of the chip and some copperflashing to the board below the A/D to sink off some heat. but I'm anal about this kind of stuff. I've had 1 relay fail but TAPR sent me a new one in a couple days.

[K1JJ]

That is, if you can figure out the TAPR web page, and figure out which modules are available anymore, and decipher what modules you actually need to make a working radio.  Oops - that ONE module you need is now no longer available  

Yep, I got the same impression at first, Johnny.  Axe Frank - I was getting frustrated thinking I may get stuck if they folded...  

But all of the boards are available to build a rig once you dig thru it. Gerd in Germany has the Penelope exciter in stock as well as Mercury receiver boards. ( with a 2 week wait)

Gerd Loch [gerd.loch@loch-leiterplatten.de]

They are planning a Hermes transceiver board which may be the reason for stopping production, I dunno.  Everything else needed is available now from TAPR. You would also need one Atlas back plane, (socket frame)  a Metis communications board,  one ref clock if you planned on two Mercurys for diversity, a Pandora enclosure box and power supplies.   Everything to build a transceiver is there except for adding a linear.  They have a 16w linear available and also a new "PennyLane" exciter with built-in 16w output coming out in a couple months I hear.

The no longer available boards mean a new one is coming out. I guess that's better than buying old technology and getting stuck cuz they need to blow thru their old inventory.

Price-wise, compared to other offerings, they are a bargain. We just need to axe lots of questions and read the details. The marketing and presentation of the site is poor, I must say.  The alternative is to pay top dollar to the Flexes of the whirl..

T

[KM1H]

Collins S Line and Kenwood hybrids are all NFB with reportedly IMD in the -40's and not having to baby the finals at QRP.

You could also bypass the 1000D heat and IMD generators and take that 100mw into a distributed amp with output filters and wind up with a 500KHz to 150MHz capable amp.

[W1VD]

Have measured several Collins 32S-3 transmitters at -40 dB 3rd IMD after NFB adjustment. Assume most hybrid rigs with clean predrivers could do the same.

[K1JJ]

Today I was sent IMD spec charts from a German who tested Penelope, the HPSDR exciter. It's only 500mW, but the specs show OVER -70db IP3 numbers, depending on power and freq. Incredible.  He also showed me a 500 mW to 150w SS CCI amplifier combo that ran class A  amplifying Penny.  It was showing well over -50db 3rd on the charts.

Help me - I'm falling into the SDR darkside abyss! (Theres no escape)

T

[Steve - K4HX]

As Carl noted, I think some of the Kenwoods (TS-820/830) were in this range for IMD too. Seems like we've taken a big step backwards. Most recent transceivers are in the low 30s! Add in synth noise and it's a good thing there are less hams on the are these days.

Have measured several Collins 32S-3 transmitters at -40 dB 3rd IMD after NFB adjustment. Assume most hybrid rigs with clean predrivers could do the same.

[K1JJ]

Most recent transceivers are in the low 30s! Add in synth noise and it's a good thing there are less hams on the are these days.

Yeah, and add in a big QRO amplifier and the effective whiner QRM IMD drops down into the abominable low -20's...

[WA1GFZ]

We don't need no stinking synthesizers or DDS crap generators.
It is a disease. But Tom now your going to need a good Tempest computer.
Good thing the antennas are out in the field.

[K1JJ]

We don't need no stinking synthesizers or DDS crap generators.
It is a disease. But Tom now your going to need a good Tempest computer.
Good thing the antennas are out in the field.

A Tempest computer?  Is that like a Lemans computer - or is a GTO computer better?   

I'm stuck with a 5 year old, 2-core 2.5ghz machine that better lick it and like it.

T

[WA1GFZ]

A Tempest is the sleeper machine. Same frame as a GTO and looks like a family car.....

[K1JJ]

http://www.cryptek.com/products/emanation_security_products/tempest_desktop_computers/emcon_tempest_level_2_pc

I see they DO exist. Are these the disco duck high-end dreamboats of the SDR guys?  Why are they only Duo-core?   Chuck tells me he bought a quad-core for his Flex 5K.    I don't wanna be left in the disco-dust here...

T

[WA1GFZ]

RF getting into the computer can be an issue. That was my only point.
Tempest machines had extra shielding, they didn't radiate so spys couldn't hear your bits.
I lock my machine up every once in a while. I thought I had it licked but it is back with the 3 KAZ feedlines coming into the shack. Time for a bead job and a better cable layout. Now they JS dangle from the window.

[WA1GFZ]

Tom, I'm running a Dell precision 650 dual dual core 2.4 GHz. I picked it up at the Pratt surplus store for under $200. I'm usually running under 10% horse power. I bet the new Ethrnet interface will be even better.

[KM1H]

Back in days of old when hams were bold I had Tempest clearance at Sanders and then picked up at Wang. Amazing what the bad guys could hear across the street from a guarded secure building back then. The spook outfit gave a demo at Sanders and at Wang and also tested everything they bought from us on site.

Steve, a TS-830, which is what I uses to test amps and drive a HB xvtr for those 6M conversions will do -42dB with just a standard tune for max power tuneup. Tweak a bit and you can pick up 2-3 more. Its somewhere south of -55 out of the 10mw xvtr port and no phase noise to speak of. Im using 3 more to drive transverters in the shack for those reasons.....and people claim its my location that hears so well A good hilltop and a noisy radio sucks no matter how you look at it and drives others bonkers on TX when the band noise floor is at/below galatic noise.

[Steve - K4HX]

Those are some impressive numbers Carl.

[WA1GFZ]

Carl, I remember testing at Sanders once and old Bob Samson talking about tempest testing. He couldn't let us in the test area though.