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Heathkit SB-303 RF rocket replacement

Discussion in '"Boat Anchor" & Classic Equipment' started by KM4HNF, Jun 12, 2021.

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  1. KM4HNF

    KM4HNF Ham Member QRZ Page

    I have a very nice Heathkit SB-303 receiver, but the connector for HF input use is inconvenient to me. Would like to replace it with a SO-239 connector.
    Is it as simple as drilling the bigger whole, and then transferring the two coax wires over from the RF (HF) connector to the SO-239?
    I see there is a coil there connected to the HF socket as well, that I assume I need to move also?

    Input and advice appreciated.

  2. KM4HNF

    KM4HNF Ham Member QRZ Page

  3. KM4HNF

    KM4HNF Ham Member QRZ Page

    ...drilling the whole bigger, I meant!!!
  4. VE7DQ

    VE7DQ Ham Member QRZ Page

    Ya, sure.

    You might consider using a BNC female chassis mount connector; if you use the type with the nut on the back instead of the flange, I believe it may fit in the same size (or very nearly) hole the RCA connector uses.

    Cheers! :D
  5. KI4ZNV

    KI4ZNV Ham Member QRZ Page

    Agreed. BNC is more convenient and very reliable and will prevent having to hack up the chassis at all.
  6. K8CCA

    K8CCA Ham Member QRZ Page

    I am not sure if a SO-239 would fit, but the RCA jacks worked fine for all these decades. I used to not like them as well, but after a while they don't bother me. I guess they are like a new pair of underwear, at first kinda constricting and uncomfortable, but eventually they become part of you lol.

    Just build up some RCA to PL-259 jumpers 3-5 feet long and then you can use them. Collins gear uses RCA jacks as well, so they must be ok and I can't imagine anyone hacking up Collins gear to add these connectors. My vote is to leave alone and make up some cables. You won't even know once the gear is on your desk and operating.
  7. AG5RJ

    AG5RJ Ham Member QRZ Page

    I too would leave the whole hole thing alone and use an adaptor, taking care not to leverage against the RCA and crack the ceramic inside.

    Lots of people assume today that an RCA phono jack must be a terrible idea for an RF connector, but as some very knowledgeable older gentlemen, some now SK, have written on QRZ pages, the RCA's were tested to be good to many MHz and 100 watts, well suited to the tasks assigned by Heath and Collins and perhaps others. Just make sure your RCA plugs are a snug fit. I have tables full of Heath SB gear, plus Collins and Drake that use them. I give the jack inner conductor sleeves a little squeeze while the rigs are apart, then make sure the plug outer shell fingers are snug. Keeps the cables from falling out due to wiggle-worn jacks. I still use the crummy little solder-on RCA plugs like Heath supplied with the kits, because I like the period look! They also don't fail; no twist-on or compression connections.

    Having said all that, my SB-303 basket case came with an SO-239 hacked into the rear panel. Since I'm using RCA for receiving antenna at the moment, I did the reverse of what you propose. I tacked a short piece of coax to the SO-239 and hung an RCA jack out the back panel in parallel. Works fine.

    Glenn Zook, SK, former Collins employee and prolific QRZ poster who schooled me on the suitability of the RCA connectors, also used to frequently recommend the SB-301 over the 303. I have them stacked one atop the other just beyond my left hand as I type. He was right. The 301 is a lot better radio. The 303's internal noise is incredible...hisssssssssssss! I haven't figured out why they command such premium prices.

    Alan AG5RJ
    KG5IPO likes this.

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