FM3 Question

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.

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.

Tks Peter, will check all you have listed.