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RM KL503 & SSB compatibility

Discussion in 'General CB Services Discussion' started by Dereka5, Jul 29, 2021.

  1. secret squirrel

    secret squirrel Lustrous Potentate

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    I almost forgot. Handy Andy reminded me. I had to add this to my setup after adding the KL503 HD. Drake TV-3300 Low Pass Filter, 1970s style.
    Drake.jpg


     
    #16 secret squirrel, Jul 31, 2021
    Last edited: Jul 31, 2021
    Dereka5, Handy Andy and Slowmover like this.

  2. Eldorado828

    Eldorado828 8-2-8 in the Lonestar State

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    Maybe @NightThumper can chime in here, he's used the 503hd and I'm pretty sure that it's been on 11 meters.
     
    secret squirrel likes this.
  3. NightThumper

    NightThumper Sr. Member

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    The KL-503HD works great on SSB 11 meters. No modifications and good reports. Before purchasing the KL-503HD I seem to remember reading I believe on the Copper Electronics forum someone complaining about the plain Jane KL-503 on SSB, can’t remember off hand what they said the difference was on SSB…I’m thinking it had something to do with the delay on the 503 vs 503HD. Again my 503HD worked great on 11 meter SSB no complaints from me or anyone else.

    Used three radios on SSB with the KL-503HD….IC-7300 (turned down), DX99V2 and RCI2950 (not jacked up)

    Brad
    South of Pittsburgh

    One of the nice things about using the IC-7300 (Ham radio)is that unlike Export or CB SSB radios, when you turn down the power the PEP goes down as well on the IC-7300…try that on an Export or plain CB radio. Only way to cut PEP on those radios is to cut the mic gain. The only thing variable power typical cuts back/down on is Dead Key AM, otherwise PEP is nearly the same across the board. That’s the way it is on Galaxy, Cobra and Lincoln.

    Thanks for waking me up there Eldorado828…LOL

    Edit 1:52pm EST: Added pics from early KL-503HD output
     

    Attached Files:

    #18 NightThumper, Jul 31, 2021
    Last edited: Jul 31, 2021
  4. Slowmover

    Slowmover Supporting Member

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    Glad I haven’t gone to hooking up willy-nilly without some advice as seen here and in other threads.
     
    undertaker and secret squirrel like this.
  5. Dereka5

    Dereka5 Member

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    Guys,

    I decided to ditch the KL503 & instead amend my order to a KL505.

    I'll no doubt purchase a KL503 at a later date, though, if the price is right.

    I'll update this thread on Monday when I've tested the Amp'.
     
  6. NightThumper

    NightThumper Sr. Member

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    If you don’t mind me asking what vendor in the US had them in stock?

    I’ve seen a few disclaimers that they won’t ship to the US

    Thanks
    Brad
     
    secret squirrel likes this.
  7. NightThumper

    NightThumper Sr. Member

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    One thing I know about you for sure…NOTHING is ever done WILLY-NILLY sir.
     
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  8. Dereka5

    Dereka5 Member

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    Hi Brad,

    I'm in the UK, but I bought mine from here - https://www.radioworld.co.uk/search/products?keywords=Kl505+

    I've only just realised that the members here are predominantly based in the Americas - great forum, though, with a wealth of information.
     
  9. Dereka5

    Dereka5 Member

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    The 505 arrived today & works a dream on 11m, @Handy Andy.

    Sounds great on SSB, uses 4 x RM SD1446 Transistors, and here are the results: 4w in = 150w out, 5w = 180w, 6w = 200w, and 7w = 220w out.

    I didn't want to push it anymore than 7 watts, and I only keyed for about 10 seconds then.

    Only curious, but what's the highest input and output power this would accept & do respectively?


    Here are some images of the internals. Seems it uses 4 x "RM SD1446" Transistors, but I'm certain the SD1446 were discontinued years ago - so I'm not sure what these are?

    PS - L1 to L4 are missing on this (close to the RTX socket) 20210802_214220.jpg 20210802_213700.jpg
     
  10. ForestRunner98

    ForestRunner98 917 SoCal

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    I see that 11m solder bridge....sweet!!!!!
     
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  11. 9C1Driver

    9C1Driver Sr. Member

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    So on SSB 7 watts PEP gives you 220 out? Wow, must be very much a low drive amp.
     
    Dereka5 likes this.
  12. Dereka5

    Dereka5 Member

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    The instructions for this say 7W is optimum, but it accepts 10W maximum before compression occurs.

    I'm quite impressed with it, and glad I ditched the KL503 now.
     
    Handy Andy likes this.
  13. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    I find this interesting.

    In the USA - these spots are important...

    Re-read the first few posts you'll see where this reference comes into play.

    upload_2021-8-3_7-59-53.png
    (HINT: SWR BLOCK)​

    That's' where you'll find it...
     
  14. Eldorado828

    Eldorado828 8-2-8 in the Lonestar State

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    So the euro version has sd1446 while the US version has the rm3 & rm4?

    Or is this a completely different animal?
     
  15. Dereka5

    Dereka5 Member

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    I'm not convinced they are SD1446, even though they're labelled as RM SD1446.

    As far as I'm aware, the SD1446 was obsoleted a while ago.

    Furthermore, the SD1446 is capable of easily doing around 80W, so 4 x SD1446 would do 320W if pushed - but no more than ~240W will be achieved from the KL505.

    I do wonder, though, if RM got a big batch of SD1446 rejects (low gain), hence why they're marked RM SD1446.

    On another note, the schematic diagram provided with this KL505 says they're using 4 x SD1407 which are expensive 28V devices!
     

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