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RF Attenuation HW-32A

Discussion in '"Boat Anchor" & Classic Equipment' started by W3DKY, May 29, 2019.

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  1. W3DKY

    W3DKY Ham Member QRZ Page

    Hi when i am in the PTT mode does the above pot control RF output and in the receive mode does it function for RF input as well?
    Thanks
     
  2. K3XR

    K3XR Ham Member QRZ Page

    Heathkit does a very good job of explaining the operation of their rigs. Just checked my manual for the HW-12A which is the same rig but for 75-meters. Might be a good idea to secure a manual for your radio. Heathkit manuals are a little more difficult to find online.
     
  3. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Not sure what you're talking about. There is no 'RF Attenuation' pot on the HW-32A. There is an RF Gain pot but that's definitely a receive only function and does not influence transmit power.

    Basically older rigs, even some older solid state rigs did not include an RF output power level adjust pot or SSB mode. Many had a Carrier level adjustment that could be used to control power in CW mode but an SSB power output level controller is a relatively modern addition to ham rigs and definitely does not exist on something like the HW-32A. On rigs like that if you want to reduce SSB PEP you either turn down the mic gain (not ideal) or you build a small negative voltage supply and inject it into the rear panel ALC input(on rigs with ALC inputs intended to connect to amplifiers) to limit peak SSB power which unfortunately isn't that easy to do on the HW-32A as it lacks an external ALC input though it would be possible to add one with a bit of effort.

    upload_2019-5-29_8-25-11.png
     
  4. WA5VGO

    WA5VGO Ham Member QRZ Page

    Actually, there is a control labeled RF ATTN. It’s operated by the lever behind the AF Gain. It controls the gain of the receiver. It has no effect on the transmitter.
     
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Interesting, apparently mine was the older HW-32 as shown in the Heath illustration as I didn't have any paddle controllers behind knobs and had an explicit RF Gain control. Is that really an RF attenuator controlled by that paddle or is it just a relabeled RF Gain control as it appears they removed the RF Gain control on the 32A model? Either way, to the OPs question these don't do anything to change transmit power as you posted.
     
  6. WA5VGO

    WA5VGO Ham Member QRZ Page

    It’s really not an attenuator. It controls the cathode bias of the RF amplifier. Why Heathkit chose labeled it that way is a mystery to me.
     

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