[AMRadio] heathkit swr bridge diodes


Brett gazdzinski brett.gazdzinski at verizonbusiness.com
Tue Jan 30 21:39:07 EST 2007


I took the 1N34a's out and put in some 1N270T's.
1N32a's are rated at 60 volts and 5 ma per the bag of
them that I have.
The 1N270t is rated for 80 volts and 200 ma per the bag.

On the SA-2060 series tuners, you have to remove the
box on the back that holds the switch, then drill out
rivets holding the board in, unsolder the wire that runs
from the input through the pickup coil, I unsoldered it at
the switch. You can then get the board out enough to
work on it. 
To get at the pots to calibrate it, I drilled 4 small
holes in the box facing the 4 pots that set the
high and low power, forward and reflected.

Using another meter, I adjusted the pots so the low and high
power scales read correct.

Ran the thing up to full power with modulation without problems.
Good as new.

Brett
N2DTS


> -----Original Message-----
> From: amradio-bounces at mailman.qth.net 
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Geoff/W5OMR
> Sent: Tuesday, January 30, 2007 2:11 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] new antenna and matchbox a bust.
> 
> Brett gazdzinski wrote:
> > Ok, I have some diodes marked fast switching,
> > rated at 200 volts and 200ma I think.
> > The 1N34a's are rated at something like 60 volts
> > and 40ma.
> > I wonder if the fast switchers would work.
> > Its such a pain in the butt to get at the diodes
> > in the tuner, and I don't think you can adjust
> > the pots with the tuner working as its built
> > into the antenna switch part.
> 
> I seem to recall that you're using the Heathkit SA-2060 impedance 
> matching device, Brett.  Is this correct?
> 
> I'm watching this thread with baited anticipation.  Let me 
> know how you 
> come out with it.
> 
> I had the same problem with mine, when moving back up from 
> 3650kc/s to 
> 3880kcs on the day after the Band warming party on 15 December, 2006.
> I moved back to 3880kc/s and hit the thing with what was 350w into an 
> infinite SWR.
> 
> Makes me wish I had a 20w monolithic RF power -brick- in 
> which I could 
> just punch up a frequency, adjust the impedance matching device.
> 
> Perhaps some little 100w ricebox w/built-in SWR protection on a coax 
> switch with the AM receiver.  Flip to the solid-state rig, key it up, 
> adjust the knobs, and then fire up the big-rig into the load.
> 
> Anyway... fast switching diodes. are what's needed, and as little of 
> forward bias as possible.
> 
> There's an adjustment trimmer capacitor in there, that looks like it 
> couldn't handle 25w.  You might check it as well, and see if it's not 
> zorched.
> 
> Good luck
> 
> --
> 73, etc
> -Geoff/W5OMR
> 
>> 




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