[VHFcontesting] [NEWSVHF] Long shot about Bird product the 6154 wattmeter.

[David Olean]

Hello VHFers,

This is a follow up to my original e mail asking for advice on repairing 
a Bird 6154 150 watt wattmeter/ load.  I was hoping to find info on how 
to proceed, but met with no success.  My idea of finding a grizzled old 
Bird employee turned up nothing.  Info on the web is about nil.  I ended 
up getting a new 6154 that appears to work. That left me with the old 
Bird 6154 that worked on the low ranges (5 and 15 watts) but was way out 
of cal on 50 and 150 watts.  The high range was way out of whack! With 
nothing to lose, I dug in and have pretty much fixed it back to almost 
perfect, Along the way, I learned a few things.  I have noted that I am 
seeing a higher indicated RF level above the 222 MHz band. 432 MHz is 
reading about 0.9 dB too high. I am not surprised as I had to disturb 
the parallel capacity of a capacitive divider network on the output of 
the diode that sets the freq response. I had to unsolder a chunk of 
siver plated brass that did double duty as part of the capacitive 
network. When I resoldered things I made no attempt to get things back 
in the EXACT position. Hey, I only had two hands and one of them is 
shakier than the  Waco Kid in "BLAZING SADDLES"!

When I took everything apart, I found that the capacitive probe had been 
adjusted so far in that it fell off and was laying there inside causing 
all sorts of errors. I re attached everything and soldered the assembly 
back together.  I can easily add a few pf externally and am hoping that 
I can flatten the curve a bit. I'll write it up with pictures and 
arrows. The 6154 can easily be re calibrated.

73

Dave K1WHS

On 2/29/2024 12:40 PM, David Olean wrote:
> I know this is a long shot, but my Bird 6154 wattmeter seems to have 
> developed a serious problem and I need advice on fixing it. The thing 
> has two ranges with a crystal diode that plugs into two connectors. 05 
> and 0-15 watts works fine. The 50 and 150 watt position does not. It 
> is way out of calibration. It used to work FB. (?)  I am looking for 
> some grizzled and crotchety old Bird employee who has the tribal 
> knowledge to effect the repair. To calibrate these things you poke a 
> small allen wrench into two openings on either side of the input 
> housing. There is a hole for each range. The low power side works 
> great and works fine. The allen wrench will turn something inside and 
> adjust the power setting. , but when I stick the allen wrench in the 
> other side, I can feel no set screw adjuster so I think some Bozo may 
> have turned the setting in too far and messed things up. I have to 
> disassemble it, but it looks all soldered together.  The guts are held 
> in with a threaded locking nut. I can loosen that, but there is no way 
> to pull the innards out without unsoldering things.  It looks real dicey.
>
> I need to find someone who knows how they are built and can steer me 
> properly. If I can't find anyone, I am on my own and will hope for the 
> best, but we all know how that all works out.
>
> HELP!
> 73
>
> Dave K1WHS
>
> ______________________________________________________________
> NEWSVHF mailing list
> Home: http://mailman.qth.net/mailman/listinfo/newsvhf
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:NEWSVHF at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html