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President JFK 2 400 channel mod

Posted: 15 May 2019, 12:24
by Papa Jupe
At first sight, this post may appear to be in the wrong group..

However, it's not so much the 'mod' that I'm concerned about, but more the 'results'.

As far as I'm aware, if I snip a little wire, and move a little jumper, my President JFK 2 will transform into an all-singing all-dancing 400 channel machine.

Not that I condone such behaviour.

My first thought is in excitement and amazement.

Being in the UK, this is soon replaced by the question of why one would want to create 10 times the number of empty channels.

However, laying that fact aside for the moment, and pretending that there was indeed more traffic than in reality - what would the benefit of having so many more extra channels be?

Is it just the luxury of having more free slots to move a conversation over to, or is there a bigger picture I'm not aware of, with regard to the additional frequency ranges?

Re: President JFK 2 400 channel mod

Posted: 15 May 2019, 15:54
by dt307
10m fm can be great when open
a place to escape any loons with 80 channels only
i know what you mean tho i dont add the low band to 40 ch sets i mod unless i am pressed as no point no 1 on there

Re: President JFK 2 400 channel mod

Posted: 16 May 2019, 11:13
by Papa Jupe

However, If one 'did' decide to go this mod route:

Don't laugh, but my homebase CB antenna consists of a 5ft stinger screwed to the side of my garage roof, with a couple of wires running horizontal for a groundplane.

I get really good SWR with that, just touching 1.5 on both 40 and 1.

Height is an issue - I live in a conservation area and need to get planning permission if I want to even hang out the washing. But I get by with the low level as it is as I have a fairly open aspect on one side.

If I was to open up the 400 channels on this machine with same antenna configuration, might that introduce some tuning issues?

I can't afford a better antenna, and so it might be a futile exercise if I were unlikely to get a good SWR.

Re: President JFK 2 400 channel mod

Posted: 16 May 2019, 19:13
by The Collector
It's highly unlikely though that too many people within your say 10mile capture radius also have a radio with 400 channels on.

Personally I wouldn't bother unless there's someone 50yards away with a large twig and big burner that wipes out 300channels worth of frequencies. You can try and get a bit further away then ;)

My old mate Andy had a Midland 48 that had a similar mod done to it. There was one person that he knew that could also do that. I couldn't (80ch Uniden 200) so it pee'd me off when I pretty much knew he was down somewhere whete I couldn't contact him and there was no way to let him know I was up on the UK channels calling him (he had no phone or landline). I almost bought a cheap modded radio with the 10 blocks on just to tell him I was about, but I thought why bother.

Re: President JFK 2 400 channel mod

Posted: 16 May 2019, 20:23
by Papa Jupe
Yeah, i hear that..

I think I'll just stick with the standard legal 80 empty channels, and work on improving my antenna configuration:

A cliff behind me but an open aspect over the River Forth in front.

Ok for marine, but i can't get too much from either side for other hurdles in the way - hills and buildings and such.

I'm ok from the Forth Bridges up to to Grangemouth, but can't quite hear any Edinburgh broadcasts with my current setup, unless i stand upstairs on my tiptoes.

I guess opening up another 320 channels with my current setup would just be a bit wishful thinking.

Re: President JFK 2 400 channel mod

Posted: 16 May 2019, 21:45
by The Collector
Can you upgrade the 5ft Springer/Stinger to a 9ft tank whip up in the loft with a few spaced 9ft wires? If not and you had to put it outside, it'd still be stealthy, but could possibly well give you 100%+ more distance just for about £20 plus postage.

Re: President JFK 2 400 channel mod

Posted: 17 May 2019, 11:48
by Papa Jupe

You had me at "9ft tank whip.."

Run a quick Google search, and found some great feedback for these bad boy's.

I've ordered one up from Thunderpole, and it's on the way.

It won't go up in the loft though - I don't have one. But I think it would fit in with the conservation concerns just fine if I swap it over for the stinger, and a fresh review of the ground plane wiring.

Ok, it'll stick up another 4 ft, but shouldn't be noticed by meddling neighbours.

Also, I'm not on the CB 'all' the time, so might hitch up a quick release connector on the mount and just throw it up when i'm 'in the mood'.

Saves the additional worry of poking the neighbours eyes out when it's really windy.

Thanks for the suggestion - you've made my day.

Re: President JFK 2 400 channel mod

Posted: 17 May 2019, 12:30
by The Collector
You could always use a bit of nylon fishing line to stop it - pardon the pun - whipping about. 2 or 3 little guy lines should keep it upright and it'll stop your signal wavering if used in windy conditions, like car signals used to go up and down as the whip jigged about.

Re: President JFK 2 400 channel mod

Posted: 30 May 2019, 20:06
by Papa Jupe
Ok, the Tank Whip is up, and seems like reasonable results..

I realised that I should be making use of a heavy metal gutter running underneath my existing ground plane wires, so took a tap from the bracket to a bolt through a hole in the gutter.

The readings aren't too shoddy, but I'm sure could be bettered with a little patience and ingenuity.

The ground plane is very directional - North South. So not ideal.

I could do with some additional wires running East and West, but the roof slopes up to the West and there isn't any roof at all to the East. Just my neighbour's garden.

SWR runs 1.2 through all the channels.

For some reason I only see 3w output at the channel 40 end tho, which I'm not too sure about.

Traffic is so sparse around here, it'll take a while to compile any decent statistics.

Quite happy though. Looks the biz if nothing else.