开云体育

I looked for you yesterday.

Michael,

Laurence = Firstly both the CIA and Russkies in Moscow head office? read this site looking to improve battlefield communications,? so Laurence most likely has altered the balance of world power.? ?..? I knew something like this would happen.
Secondly if you get xtals of no name brand ...mm.. they might be all on same nom freq but certainly they are likely to be? near enough design for micro controllers and such and not formal communication xtals. If they work for you,? then you have the deal of the century. Others like? Alltronics in Calif? sell microprocessor spec xtals for? up to one USdollar each.? ?If they all come with same mafr brand on side then you are in with a good chance - like ECE or Fox.?

Thanks Raj.....sounds like a good idea!

Michael

I tried going down to 10pF in C102 and then put a trimmer in C103 but it still was too narrow.

May try changing those caps tomorrow and see what happens.

Michael

Howdy friends,

Still haven't licked this. I made a short video to demonstrate the problem and show what I've tried so far--which involves stripping away almost everything but the main board.
Kindly have a look and let me know what you think I should try next.

I appreciate your applied expertise. :)

Ashhar,

Nudge. I'm sure you're incredibly busy, and the v3 boards are ancient history at this point. But they're important history for those of us with that hardware.
(Or perhaps the latest files are out there, and only the link on the page needs to be updated)

:)

Cheers et 73, -m

This is another pass on the LPF board....being tested.?

1) this one is meant to install under the covers of the uBITX, Board is 68mm x 48.4mm.
2) uses the existing uBITX LPF components moved over to small plug-in LPFs (can also use the QRP Labs
? ? LPFs or your own LPF design),
3) uses basically the physical layout of the LPF board as outlined by Allison in the Wiki section, the high band
? ? LPF?is ALWAYS in the circuit Rx or Tx.
4) if Tx voltage is present, the LPF board is routed to T11 and removed from the Rx section which is grounded.
5) if one of the bands, other than the high band, is selected by the TxA, TxB, or TxC, it inserts that LPF AND the
? ? high band LPF in series for Tx. Really reduces high frequency harmonics.?
6) has a 1 mH inductor in series with each relay coil for further isolation,
7) uses the smaller NAiS TQ2-H-12V relays. Good relay I have used before.?
8) extensive use of flood-fill ground and ground stitching
9) interfaces provided are: T11 (near the PA, happens to have a SMA installed for test), Ant (happens to have
? ? a SMA installed for test), Rx (near the line to Rx), TxA, TxB, TxC, Tx Voltage, and Ground

73 Kees K5BCQ


?

Jim,

That's exactly how the K2 handles it, its one of the first kit QRP rigs to use microprocessors
(more than one) for ore than a digital dial.

The software puts out Via PWM or DAC controll voltages for the BFO and the filter.

Allison

SSSSSSShhhhh!!!!!!? THIS IS MY **SECRET** U.S.A. SOURCE...

between YOU and I ONLY!!!!!

12Mhz Crystals 5 for a $1.00? or 15 cents each in lot 100 quanities...

Right! 5 for a DOLLAR.!!!.... over $75 free shipping, under $75 flat $7 shipping.. They have 1/8" uBITX volume knobs too..



Also read my review on 50ft. RG58/u cables with BNC's both ends (GO KIT SPECIAL) ... and adjustable 6.8uH inductors..
I usually get my order Calif. to Kansas in 2 days...

de W8LM

PS... they have small pf trimmers dirt cheep...65 cents..10 for $6.00
?????



.

Gary,

Good catch on the current... next time wear glasses...? THat was the max current not operating.
There is a table in the datasheet for the resistor needed.

Allison

A good reference app note on MMIC biasing from minicircuits:?


I've done 2 VHF amps, and good results with running 12V, bias resistor and choke also.
(Also had access to a top tier spectrum analyzer at that time :-)

(Recommended Device Operating Current for ERA-3SM+?is 35mA)

Regards,
Gary
AG5TX

Can I purchase just the??BITX ‘s Raduino somewhere?? Original display and Nano combination.

Its known as a Jones filter and was used by TenTec? many years backand the Elecraft K2
for a more recent example.

With matched or at least close to each in capacitance for a given voltage it can work well.
Another is to use dies with less capacitance range and parallel caps like 82pf and a?
varicap diode that can do 30pf.

The problem is the BFO has to be close to the edge of the filter and the edge is variable.
Keep them in sync may be a handful.

Sorry,

?I was just teasing a bit and didn't mean any harm. I just wanted to emphasize that it's the function that really counts in the end. ?I started work on making the steps for this on the wiki easier to follow, but haven't finished yet. ?Hopefully some would find find it useful?

73,


Mark