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My latest new transceiver.
"With a little help from my friends"
RF-280 found in the desert Interesting story
(Not this one)
Found a HAM in the USA (Thanks Dave) helped me with the manual. He gives the source to Vintage Manuals and they make a perfect copy for me and anyone else who need it.
For a very fair price, ask Mindy.
So this is a very thick manual I won't publish on my site.
If you need a detail please mail me.
This is the military version RF-280A
After some repairs and changing the meter and add a microphone.
The meter and the microphone and some other treasures was send to me from the easterbunny from Tonawanda NY. (Magic junkbox)
Buyed this RIG defect and hoped that it was complete, it was.
1. Had shortcircuit in the regulated power circuit, a defect tantalium capacitor.
2. -6 VDC missing on some opamps, set meter in middleposition and blocked power output.
A defect transistor and zener diode.
3 After warming up receive and transmit signal dissapears.
Hard to find variable resistor replaced in the L.O. circuit.
Now it works fine, halleluja.
I must say with support from my friends in the USA.
The operation table
You can see the thick manual on the table.
Tools you need for repair the RF-280
My homebrew pc-board extender card and some coax extenders.
All the Harrisses together.
RF-280 RF-230 and RF-301A
Usefull mods:
Cut these jumpers for all mode on all bands.
Silent fan mod
When powered by 115VAC or 230VAC
Adding this diode keeps the fan off in receive mode.
In transmit mode it will run.
When operating on 28VDC it is allready the normal behavior.
AM improvement mod
As you can see the filterselection for AM RX is the FM filter 28KHz bandwidth.
As a member of the SRS we use old army equipment on a net every sunday on 3705KHz. On the crowded 80 meterband a filter of 28KHz is too much.
For the TX they use the USB filter and put the carrier on the right place. So there is a one side AM signal.
With this mod I disconnect the selection diode for AM RX and make 2 new selections to the USB and LSB filters. I use them simultaniously and now I have a filter from abt 5.6 KHz wit a gap in the middle.
Improves very much AM selectivity. (ofcourse)
For the AM TX I also select the LSB filter so there is a normal DSB AM signal.
Diode selection and place overview
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