What are you using for Q90 and all the other 3904s?

Words would make the posting informative.

Allison

Glenn,

Use them in good health.? Note 3904s have gain of maybe 3 at 82.2 so you have
to rebuild the 45mhz amp completely.? Also layout at 82mhz is getting fussier than
at 45mhz.

Changing the filter will not cure the output from the power amp getting into the
wide open 45/82.2mhz amp and contributing spurs though I may move them
around.

Also the HFO (osc-3) has to go from 85mhz to 115 mhz and that meas you
exceed the SI5351 code by 6mhz.

They are most like 15khz wide but could be much wider for data use.

I can't use them as I said experiments and mods have reduced mine to a
collection of junk.? ??

One magik pill.

Allison

I'm sure our Indian folks will back me: I'm sure 'Karma' here should be 'Kudos'. Karma is the 'therefore that' result of 'because this' - the immutable eternal Logic.

73 de ZL2DEX

These are the filters. I haven't swept them but imagine they are relatively narrow 'fm' filters.

Before anybody asks, they are no longer available from ?

glenn

Bill:

This is one I used... .



David A Posthuma, WD8PUO
1 (616) 283-7703

Allison,? some nice do-able ideas there. I have some 82.2MHz crystal filters here and thought? that they may eliminate the issues above 20MHz? Happy to send you a pair if they help your project.

glenn

----snipped----------------------------------------------------------------------------------------------------

Result then is a decent 80 -17M radio.? ?Forget anything over 20mhz the filters before
the amp is much more difficult and otehr issues conspire to make it a mess.? We need
V5 to get that.

The plan for mine was a mil style man pack with 80/40/20/10 as primary bands (must have)
low power RX with AGC and 5-10W TX.? As work on ubitx proceeded it was obvious getting
that in the package identified was?not going to fit due to added blocks to make it work
and I found the power needs rather high for something I plan to run on battery.

I will have to come up with my own design to fill that need.? I already have a breadboarded
version that needs to be size reduced to fit.??

Allison

For any of the low pass fitlers the easy mod is to wire around the whole built in LPG and?
save the losses.? Then put the 3rd party filters between the antenna jack and the board.

All KT1-3 do is contribute loss and consume power.? You can use the three outputs
TX-A, TXB, And TXC with software changes to control the new board or whatever then.

Allison

Can someone give me a link for the best 4.2" display and associated products?

Bill

Brent,

I am considering Hans' low past filters and matching relay board as I have plenty of room in my box. I have no problem with a simple rotary switch to select, and I'm looking for a simple bolt on solution without butchering the board, either by just connecting to the output, or else disconnecting the existing filters, and feeding the new ones directly from the power amp. I see he also sells BPF modules.?

IF you using external filters. disable Kt1-3 and run a coax from power amp to K3.? Use external filters.

With trivial wiring and trivial code mods you can use the Raduino? to select the filters.? Stop at 17M?
though as without band pass filters you can't clean up above 20mhz.

For band pass you have to alter (butcher) the board as it has to get before the amp.? They are
not designed to handle power.? ?There are other issues that makes that messy so 20mhz and
up give it a pass or build in one filter (alter the board) and use it for only one band.

Most tuners have insufficient selectivity (not their function) to suppress spurs much.? ?Those polyvaricon
are cheap and with both sections in parallel hit about 350pf or so.? That and they are more available then
the higher power air gaped as well as smaller.? Max power is not much over 10W depending on the?
style of the tuner.? The trimmers are meaningless.

Its one of those either get in there with a precision knife or its wishful thinking.? What I can't see is why
people fear making changes.? Its the only way to satisfy the wish/need list.


Allison

Yes, a great education for the money. I am considering Hans' low past filters and matching relay board as I have plenty of room in my box. I have no problem with a simple rotary switch to select, and I'm looking for a simple bolt on solution without butchering the board, either by just connecting to the output, or else disconnecting the existing filters, and feeding the new ones directly from the power amp. I see he also sells BPF modules. Does anyone have an opinion if these would work on TX for the band's where spurs are a problem??? It would be nice as I know many qrp tuners use the polyvaricon, and I don't see? where the trimmers should be much different at qrp, but again, I defer to others with more knowledge and experience.

Thanks and 73
Brent, VE3CUS

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How did you go about adding the qrp labs filters I built mine up but haven't put them in yet. Experience is valuable in these cases. Did you remove kt1 relay and drop it in it's place?

"Both men deserving"? is a as funny as hell. What? ?? Ashan F and his younger brother Ashan Farhan the second ? Please don't ban me Arv... I could not? resist it?
.

It was fun, no question, and plenty of mental exercise.? It missed the mark
for my intended use.

If my board was intact my list might be..??

External balanced mod and filter as that cleans up the carrier leakage.
I built such a thing and put it haywired in a mint tin with a crystal
oscillator dialed in as needed and got excellent result.? The circuit
was nearly in the end identical to bitx40 analog.

Mod both TX IF for no more than 11DB from the tx side of the bidi amp.

Pull the relays.? Carefully remove all the RF tracks. and DC
running under them.? Install those or replacements from the
underside and? wire it up for 80 through 20 and forget the 10M filter.
Sounds nasty but fairly trivial bunch of wires.? I put up the base circuit
for that three times.? Go dig.

Replace the 33mhz low pass with a 20mhz low pass values.? That will
take out most if not all of the lower spurs.

Edit the code to stop at 17M.? Add the needed touch ups for the now
current relay scheme for the 80 through 17M use.

Rewire RX/TX to bypass the power amp input (rewire around K1). Use K1
for DC switching only and also to remove DC short the unused line to ground.
the whole switching scheme is nuts I'd try to use KT1 for that and dump K3.
Improve bypassing and add bead chokes to power lines all over the board.

The idea is less high power wandering around the board and leave the filters
in for RX as it helps with RX birdies.? since that also means only 1 relay per
band is active it helps with power drain.

Mod the Power amp section:?
Q90 a decent part mmbt2369 or other 600mhz FT part will do as we are stopping at 18mhz.
Play with C81 for more even power 80 to 17M.

Version A, what most might do:
Replace all the 3904s with 2n2222A and lower bias foor 20ma each idling.
Reinstall the IRF510s with shorted leads possible.? Add insulator kits and real large heatsink.

Do yourself a favor hold the power to 10W or close.? Pushing the amp to max power?
just makes you a trash bucket operator as it will never be clean when doing that.
When you do that the RF gets back into other stages and creates more issues!
If you think you need more power get a used 100W radio!

Version B for those not terrified by now:
All the parts after Predriver removed.? Rewind T8 on BN61-2402? 6t and 2 turn secondary #30.
Replace pre-driver 2n3904s with one 2n2219A and bias it for 25ma.? Rewind transformer
as 8 turns bifilar #28, connect as 4:1.
Get another Kitsandparts 5W CW amp, replace BD139s with IRF510 and bias network OR
get a QSX amp and be done.
Use coax (rg316) to connect from pre-driver output to amp module amp and from that amp
to the relay tree for filters.? There will be power and control wires.??

The above is an outline if you cannot think your way through it you will get over your head
fast.? Buy an appliance.? However if you build and like a challenge that is very nearly ground
up its very do able if you start with a working radio and work carefully.? Its in the land of
building from scratch and nearly a kit.? We left heathkit assembly back a while ago.

Result then is a decent 80 -17M radio.? ?Forget anything over 20mhz the filters before
the amp is much more difficult and otehr issues conspire to make it a mess.? We need
V5 to get that.

The plan for mine was a mil style man pack with 80/40/20/10 as primary bands (must have)
low power RX with AGC and 5-10W TX.? As work on ubitx proceeded it was obvious getting
that in the package identified was?not going to fit due to added blocks to make it work
and I found the power needs rather high for something I plan to run on battery.

I will have to come up with my own design to fill that need.? I already have a breadboarded
version that needs to be size reduced to fit.??

Allison

This is the bezel that I did for David.

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Well, it was a kit.

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