Here is some more technical information on the AMTRON VHF CONVERTER.
SCHEMATIC, PARTS LIST AND LAYOUT. ALSO..SOME TROUBLE SHOOTING IDEAS FOR SIMPLE
CIRCUITS.
SCHEMATIC, PARTS LIST AND LAYOUT. ALSO..SOME TROUBLE SHOOTING IDEAS FOR SIMPLE
CIRCUITS.
Sorry the manual I have is not in english but you can probably figure it out technically.
Remember design and conquer technique for troubleshooting . I wrote about it in page one of this topic. When I was doing my DC
trouble shooting; I wanted to separate the two dual gate mosfets part of the circuitry from the two transistors part of the circuitry.
By removing one connection of Z2 (the small choke) I removed the 12 volt line from the two DG mosfets and could then concentrate
on half the circuit at a time.
As you can see by my hand written notes on the bottom of the schematic; I am finding cross references to parts used in this
converter. These parts are highly interchangeable. NOTE: I spoke to a technician this summer who works on the modern ham radio
gear (built in the 21st century); He said most parts for the modern stuff is one of a kind and they are not interchangeable.
I use the ECG parts substitution and Identification book and draw cross references to parts I have in my inventory. ECG and NTE
(basically use the same methodology). They are on the web as well. The oscillator transistor (TR3) is a vhf oscillator Amp transistor.
It has an ft listed as 800 mhz. It oscillates well at UHF and vhf. Another transistor that is a good oscillator at vhf/uhf is the 2N5179.
It has an ft listed at 1400 mhz. I substituted this transistor into this circuit and it seems to be working ok.
trouble shooting; I wanted to separate the two dual gate mosfets part of the circuitry from the two transistors part of the circuitry.
By removing one connection of Z2 (the small choke) I removed the 12 volt line from the two DG mosfets and could then concentrate
on half the circuit at a time.
As you can see by my hand written notes on the bottom of the schematic; I am finding cross references to parts used in this
converter. These parts are highly interchangeable. NOTE: I spoke to a technician this summer who works on the modern ham radio
gear (built in the 21st century); He said most parts for the modern stuff is one of a kind and they are not interchangeable.
I use the ECG parts substitution and Identification book and draw cross references to parts I have in my inventory. ECG and NTE
(basically use the same methodology). They are on the web as well. The oscillator transistor (TR3) is a vhf oscillator Amp transistor.
It has an ft listed as 800 mhz. It oscillates well at UHF and vhf. Another transistor that is a good oscillator at vhf/uhf is the 2N5179.
It has an ft listed at 1400 mhz. I substituted this transistor into this circuit and it seems to be working ok.
Below is the physical layout of the unit. Sorry its upside down. BA136 (D1 and D2) are the protective diodes. Often protective diodes clamp
down any voltage spikes from the radio antenna and protect the sensitive mosfets or other semiconductors from voltage spikes.
This converter had at least 1 bad dg mosfet. I replaced both of them to save time because I had lots of dg mosfets (type 3n201) in my
collection. After replacing the 2 mosfets, the converter started working and receiving vhf signals on the 2 meter amateur band. YOU CAN SEE
the final fix to this converter by clicking on the link at the bottom of this page.
down any voltage spikes from the radio antenna and protect the sensitive mosfets or other semiconductors from voltage spikes.
This converter had at least 1 bad dg mosfet. I replaced both of them to save time because I had lots of dg mosfets (type 3n201) in my
collection. After replacing the 2 mosfets, the converter started working and receiving vhf signals on the 2 meter amateur band. YOU CAN SEE
the final fix to this converter by clicking on the link at the bottom of this page.
click here for page one of this series on basic trouble shooting.
click here to go to my home page (earl andrews.com) ve3ab home page
NAVIGATION LINKS
click here to go to the third (and last page in this series of troubleshooting the converter)
click here to go to the third (and last page in this series of troubleshooting the converter)