UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - President Lincoln SWR issue "only" when meter inline.

Damo666 · 15th Jun 2021, 2:47 am

@Sirius, Richard675

Thank you both for the tips, & also my gratitude to others for their kind assistance.

I've not got around to opening the Lincoln up, but one of the first things I'll be doing is nipping up all the PCB to chassis screws, then checking decoupling cap's. If this fails to remedy the problem, I'll then fit an open air choke just below the antenna feedpoint.

I've found a website that recommends the optimum amount of windings for various air wound/ferrite chokes, but some of this is beyond my low level of RF experience; I'm thinking around 20 turns of RG58, 4" diameter air wound unless I've misinterpreted the information on this site? http://www.karinya.net/g3txq/chokes/

I'm currently using 9mm RG213, & frankly, it's awful in terms of maneuverability. I've got about 3 metres of it spare on my setup, & it's difficult to hide here in the bedroom.

I'm going to invest in something a little thinner, perhaps good quality RG58 or something - then keep cutting around 1 metre at a time in the hope it sorts the problem. In the meantime, I'm going to cut about 2ft at a time from this RG213 and see if that improves things. I've got nothing to lose, as I've got about 3 metres redundant & in the way.

@Sirius - when the SWR meter is placed inline, both this meter & the rig SWR meter show exactly the same poor SWR.

I could use this rig connected directly to the antenna & forget all this ever happened, but I'm adamant that I now need to get this anomaly sorted out.

15th Jun 2021, 2:47 am	#12
Damo666 Hexode Join Date: Jan 2010 Location: Blackburn, Lancashire, UK. Posts: 399	Re: President Lincoln SWR issue "only" when meter inline. @Sirius, Richard675 Thank you both for the tips, & also my gratitude to others for their kind assistance. I've not got around to opening the Lincoln up, but one of the first things I'll be doing is nipping up all the PCB to chassis screws, then checking decoupling cap's. If this fails to remedy the problem, I'll then fit an open air choke just below the antenna feedpoint. I've found a website that recommends the optimum amount of windings for various air wound/ferrite chokes, but some of this is beyond my low level of RF experience; I'm thinking around 20 turns of RG58, 4" diameter air wound unless I've misinterpreted the information on this site? http://www.karinya.net/g3txq/chokes/ I'm currently using 9mm RG213, & frankly, it's awful in terms of maneuverability. I've got about 3 metres of it spare on my setup, & it's difficult to hide here in the bedroom. I'm going to invest in something a little thinner, perhaps good quality RG58 or something - then keep cutting around 1 metre at a time in the hope it sorts the problem. In the meantime, I'm going to cut about 2ft at a time from this RG213 and see if that improves things. I've got nothing to lose, as I've got about 3 metres redundant & in the way. @Sirius - when the SWR meter is placed inline, both this meter & the rig SWR meter show exactly the same poor SWR. I could use this rig connected directly to the antenna & forget all this ever happened, but I'm adamant that I now need to get this anomaly sorted out. Last edited by Damo666; 15th Jun 2021 at 2:53 am.