b

[ve8xj]

I

[k4kyv]

I would experiment.  Set it close enough that it sparks whenever the transmitter plate supply is turned on, then widen the gap just a little past the point where it quits sparking under normal conditions.  Should be somewhere between 1/16" and 1/8".

[w4bfs]

the Johnson 500 has 2 gaps .... the one across the mod xfmr is set at .018" .... seems pretty close ... this should still be useful as the plate impedances and power levels are similar to BC610  

the gap you are concerned with is in the power supply filter choke and gets tickled each time the transmitter is unkeyed .... the choke is rated at 7kv as I recall .... the .125" sounds more like it but I think this calls for a transient snubber on the choke to remove this unnecessary stress

[W2PFY]

The BC-610 C & D models do not have a spark gap on the reactor. On my C model, now sold, a carbon path from one of the terminals to the chassis was created. I did my best dentistry on the burn area and put something on it. Forgot what I used but never had a problem thereafter.

I don't believe any of the 610 series have spark gaps on the modulation transformer primary. What I did to protect the transformer was to place on each heat dissipation plate cap a piece of # 22 gauge wire that would go over to the other other cap midway with a bend in it.  I separated both bent wires spaced the thickness of a match book cover. I would hear them snap from time to time knowing they were doing their job. I think the match book setting would also be good on a reactor in a 610 at their voltage levels.

[N8ETQ]

  My "E" does not have em' either.

Must have been a Korea thing.

/Dan

[K9PNP]

Out of curiosity I looked at the Tech Manual [TM 11-826] for the E thru I versions.  All it says about the spark gap is "In the H and I models, filter choke L4 has a closely spaced spark gap across its terminals."  There are no further references to it except in the same paragraph explaining why it's there.  According to the specs for those models, L4 is rated at 10KV.  For the earlier models [A thru D and some of the E's] it was rated at 5 KV.  So much for the Tech Manual answer, which I presume agrees with yours.  If I could remember what the breakdown voltage of air was, I could compute the spacing roughly.  It's unusual that the military then did not make a comment of maintaining the spark gap; they did everything else.

[ve8xj]

[connector!!

[ve8xj]

Out of curiosity I looked at the Tech Manual [TM 11-826] for the E thru I versions.  All it says about the spark gap is "In the H and I models, filter choke L4 has a closely spaced spark gap across its terminals."  There are no further references to it except in the same paragraph explaining why it's there.  According to the specs for those models, L4 is rated at 10KV.  For the earlier models [A thru D and some of the E's] it was rated at 5 KV.  So much for the Tech Manual answer, which I presume agrees with yours.  If I could remember what the breakdown voltage of air was, I could compute the spacing roughly.  It's unusual that the military then did not make a comment of maintaining the spark gap; they did everything else.

Must be like the R-390 s-meters Top Secret!! The height of spark gap technology. In the end it wasn't my problem , got the rig up and going.But I certainly learned something.