The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    FM3 Question

    Share
    avatar
    CNCfan

    Posts : 31
    Join date : 2018-08-13
    Age : 70
    Location : Houston Texas

    FM3 Question

    Post by CNCfan on Sun Nov 04, 2018 2:56 pm

    When I touch the FM3 while tuning in a station the strength of the signal is much better than when I am not
    touching it. Wondering what causes this.

    So far I have only replace the power supply caps with the unit that Dynaco Designs sells. (unit also did this before the swap out) Plan on
    getting the FM-3 Economy Upgrade Kit from Dynaco Designs sells, would this help with this problem. (going to get the kit even if it would not
    help in this situation)

    Do I need to ground the unit? It has the original 2 wire power cable. Also I am using a big TV/FM antenna in the eves of the garage
    that was left by the previous owner of the house.

    avatar
    Peter W.

    Posts : 965
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: FM3 Question

    Post by Peter W. on Mon Nov 05, 2018 8:51 am

    CNCfan wrote:When I touch the FM3 while tuning in a station the strength of the signal is much better than when I am not
    touching it.  Wondering what causes this.

    So far I have only replace the power supply caps with the unit that Dynaco Designs sells.  (unit also did this before the swap out) Plan on
    getting the FM-3 Economy Upgrade Kit from Dynaco Designs sells, would this help with this problem. (going to get the kit even if it would not
    help in this situation)

    Do I need to ground the unit? It has the original 2 wire power cable.  Also I am using a big TV/FM antenna in the eves of the garage
    that was left by the previous owner of the house.  


    Have you done the full alignment? If not, do it!
    Have you made sure that the internal system-grounds are intact? The main board across the front is grounded to the chassis by-solder, and there is a bare copper wire visible underneath. As you have replaced the multi-section cap, make sure that the new board is properly grounded as well.
    Make sure that the output jacks are also properly grounded. Tighten the screws, if any, and make sure that they are making excellent contact with the patch-cords. Dynaco purchased their jacks from the lowest bidder, and their behavior is absolutely reflective of their cost.
    I generally suggest and approved of the use of a 2-wire polarized line-cord. But emphatically NOT a 3-wire cord.

    After all that, you are providing a 'field' when you touch the tuner, which is technically, a counterpoise. This increases the effectiveness of the antenna, and therefore, reception.

    https://en.wikipedia.org/wiki/Counterpoise_(ground_system)

    This normally applies in practice primarily to transmitting antenna, but the theory applies equally to a receiving antenna. Big does not necessarily equal 'good' when it comes to antenna, and even if one is both big and good, its orientation can be critical.

    There is a thread here that I started "office system" - that FM3 was pretty wretched as-received, and is now doing adequately in the catacombs of a city-block complex. They are better than many tube tuners, but do not stand up to a high-end solid-state device as to sensitivity and selectivity. But they sound fine! But, the alignment is both key and critical.
    avatar
    CNCfan

    Posts : 31
    Join date : 2018-08-13
    Age : 70
    Location : Houston Texas

    Re: FM3 Question

    Post by CNCfan on Mon Nov 05, 2018 3:41 pm

    Tks Peter, will check all you have listed.

    Sponsored content

    Re: FM3 Question

    Post by Sponsored content


      Current date/time is Tue Nov 13, 2018 9:38 pm