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My friend Rich K0ZX has been using his NanoVNA (original type) outdoors, and asked me about options for improving display visibility. I went searching for possible solutions and ran into a low-cost camera viewfinder accessory (some digital cameras also have ~2.8" LCD display, and are subject to the same visibility impairments when used outdoors.)

A few weeks ago I ordered on ebay the 2.8" LCD viewfinder listed below (now about USD 12; they seem common on ebay and I'm sure there are alternatives to consider...)



It arrived after about a month, and after popping out (inverting) the rubber material eye cup (it's shipped in a backwards configuration reduce size of shipping container) and placing it on my (very much original-era NanoVNA), it does indeed somewhat magnify the display and shield it from ambient light.

A few of caveats:

1. The touchscreen is obviously not accessible while the viewfinder is in place, and my nanovna is pure original vintage, no updates, so the manual button/switch controls leave more than a little to be desired;

2. The focus isn't quite perfect - it seems that it the small gap between the LCD plane and the viewfinder focus point caused by the PC board material takes the viewfinder slightly out of focus, but it's still quite readable, nonetheless;

3. There's no immediately obvious way to fix the viewfinder to the NanoVNA.

In any event, I wanted to pass this along to our user hhcommunity to see if it inspires any further ideas.

A few photos are attached. Please excuse the up/down inverted photos (photography hasn't been my thing since about 1962!)

Comments and observations welcomed!

73 Dave WB0GAZ wb0gaz@...

With respect to the viewer focus. Have you tried it on any other display like a smart phone, TV or computer display; from what looks like a very cheap lens, it might be what you see is what you get. If other displays look more in focus, then you could try sanding down the viewer a bit to account for the extra space caused by the case.

Another possible solution might be to use it with a smart phone where the display can be set brighter and would probably be bigger as well. I am new here, but tried "NanoVNA WebApp" on my Samsung Android today, not sure if there are others or if there is one for iPhones.

Nice discovery. Thank you. I ordered one.
Some 9 US $ only, but it has a long delivery time, though.

-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von David Feldman via groups.io
Gesendet: Samstag, 13. Juni 2020 03:43
An: [email protected]
Betreff: [nanovna-users] Possible adjunct to 2.8" NanoVNA for outdoor use - LCD viewfinder

My friend Rich K0ZX has been using his NanoVNA (original type) outdoors, and asked me about options for improving display visibility. I went searching for possible solutions and ran into a low-cost camera viewfinder accessory (some digital cameras also have ~2.8" LCD display, and are subject to the same visibility impairments when used outdoors.)

A few weeks ago I ordered on ebay the 2.8" LCD viewfinder listed below (now about USD 12; they seem common on ebay and I'm sure there are alternatives to consider...)



It arrived after about a month, and after popping out (inverting) the rubber material eye cup (it's shipped in a backwards configuration reduce size of shipping container) and placing it on my (very much original-era NanoVNA), it does indeed somewhat magnify the display and shield it from ambient light.

A few of caveats:

1. The touchscreen is obviously not accessible while the viewfinder is in place, and my nanovna is pure original vintage, no updates, so the manual button/switch controls leave more than a little to be desired;

2. The focus isn't quite perfect - it seems that it the small gap between the LCD plane and the viewfinder focus point caused by the PC board material takes the viewfinder slightly out of focus, but it's still quite readable, nonetheless;

3. There's no immediately obvious way to fix the viewfinder to the NanoVNA.

In any event, I wanted to pass this along to our user hhcommunity to see if it inspires any further ideas.

A few photos are attached. Please excuse the up/down inverted photos (photography hasn't been my thing since about 1962!)

Comments and observations welcomed!

73 Dave WB0GAZ wb0gaz@...





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There's no immediately obvious way to fix the viewfinder to the NanoVNA

mine included a thin steel frame with pressure-sensitive adhesive
that attracts viewfinder's magnets

Thank you, Oristo and DJ7BA ---

I discovered the small metal shim or bezel at the bottom of the viewfinder shipping box this morning before I read your posting (did not realize that the shim was included, or that the viewfinder used magnetic mounting).

The shim or bezel has four thin adhesive areas used to attach the shim to the camera body. I slightly trimmed the shim at one corner (it had slightly enlarged outline, perhaps to help camera owner to position the shim, but in this case the enlarged outline interferes with one of the four nanovna screws), then pressed the shim onto the front of the nanovna.

The shim does not adhere very well to the front of the nanovna; perhaps because of the material or paint used on the front layer of the nanovna package, or I impaired the shim flatness after trimming the corner, so after I attached then removed the viewfinder (the magnetic attraction between the viewfinder and the shim is quite strong and magnetic attachment would be a good solution to problem #3), the shim separated from the nanovna and remained attached to the viewfinder magnets.

The presence of the shim (it is ~1mm thickness, adding to the distance between the LCD display and the viewfinder lens) did not seem to change the image focus enough to notice - it was still slightly out of focus (with chromatic aberation), but perfectly usable. I would be happy to use it.

Considering the intended fit of the viewfinder and the very good fit otherwise to the nanovna, perhaps the nanovna 2.8" display was originally used in digital camera manufacture...

I think a more useful solution would be a replacement nanovna 2.8" front panel made from thin steel rather than FR4, but with same opening and same mounting holes. This would allow the viewfinder to directly attach to the nanovna front using the in-built magnets. It is probably required to use commercial manufacturing to make a steel front panel, so I do not think I will be able to proceed further, but I will investigate improved attachment of the viewfinder for my nanovna.

DJ7BA - I did find other listings of this type of item on ebay, some lower price maybe USD 6 with (slow) shipping. There seems to be some variations depending on camera type. My device was labeled on box as type "V1", type AY014, for Canon 5DII/7D/500D and Nikon D700/D800". I have no such cameras, so I did not consider the possible differences.

Thank you again,

Dave