SM3437 3.4 GHz amplifier everything you what to know

[VE2OLM]

Hi i try to collect all information to a single place

so here the datasheet ( thank to zl2bkc ) https://zl2bkc.files.wordpress.com/2013/01/sm3437.pdf

input is 0dbm and not what to buy a attenuator for put on my kuhne MKU 34 G3 that drive 400mw
so i mod the first gain stage remove MMIC and remplace by 20 DB PAD. (17 db may better option )

dir coupler

Then amplifier i have not have PWR and REV option and i need it so ....
feedtroug cap is stock from digi-key 410-1034-ND 2425-001-X5U0-101AALF
then need 250 to 500 ohm 0805 resistor on directional coupleur to match sensitivity you need (250 ohm = ~3.3V for 20W)
for REV is bit more complicated need to replace the circulator for one that have 30db pad instead of 50Ohm load

inout mod

next is PTT input , Datasheet said it 5V TTL , find on web to put 4.7K serit resistor for 12V input , but i chose to dray schematic of input circuit
this show that it may take 12V from sequencer or TX relay of transverter whit no mod

input circuit

probably final mod is that AMP is class "A" Bias so lot of heat , i may check later for put it in class AB for less heat dissipation and efficiency

if you have anything feel free to add it

final feet datasheet https://www.digchip.com/datasheets/down ... FLL300IP-4

predriver datasheet https://cdn.datasheetspdf.com/pdf-down/ ... evices.pdf

predriver datasheet https://pdf1.alldatasheet.com/datasheet ... 107ME.html

best 73! Marc L. VE2PN / VE2OLM

[VK7HH]

Thanks for your post. I've just got my SM3437 working. It's outputting 22W for 0dBm drive.

Just waiting on my external attenuators so I can pop them on the output of my transverter.

[VK2BLS]

Hi Hayden

Ted VK2ARA and I have just completed boxing up our Stealth 3437 amps + SGLabs 3.4Ghz transverters.
We both purchased the same 3437 amps from same supplier a while back and both came as new and sealed.
Problem is, one amp works ok and draws 8.5 amps when 12V attached and 5V TTL I/O operates and RF out, on air test fine. The other amp connected the same, does not draw any current when connected to 12V. After many screws removed and wiring checks we think the amp may have been inadvertently damaged.
Other than the PDF spec sheets and the photos above, we have not been able to locate any circuit diagrams to assist with fault finding.
Would you or others possibly have any circuit documentation or suggestions that may assist?

73 Darrell

[VK7HH]

Hi Darrell,
I don't really have any circuits or anything more than what is provided when purchased.

I assume on the faulty unit you took the TTL I/O line high (or to 5V) and it still wasn't drawing current. I'd say it is dead yes.
Can you contact the supplier and say it was DOA?

I know Peter VK7PD had an issue with one of his amps and fixed it (bad cap from what I remember).
Sorry I can't be of more help.

[VK2BLS]

Hi Hayden,

Thanks for fast reply.
Amp only draws 145mA when 12V applied and no change when 5V I/O triggerd. We got the amps about 18 months ago.
The warranty seal opened to inspect internals, so a return is prob not on.

Cheers,
Darrell

[VK2BLS]

I did find a nice Hi Res photo of PA board.

73 Darrell