[Johnson] Ranger VFO chirp on 40 Meters

[David Harmon]

That's it.


73

David Harmon
K6XYZ
Sperry, OK

-----Original Message-----
From: johnson-bounces at mailman.qth.net
[mailto:johnson-bounces at mailman.qth.net] On Behalf Of Mike K9UW
Sent: Friday, March 7, 2014 9:55 AM
To: johnson at mailman.qth.net
Subject: Re: [Johnson] Ranger VFO chirp on 40 Meters

 

Is this the link you're referring to,
Brian?

http://www.w8ji.com/johnson_vfo_chirp_jump.htm [5]

73, de Mike,
K9UW
Amherst, WI 

On Mar 07, 2014, Brian wrote: 

> There is a
relatively simple modification to fix this problem but I don't remember
where it is however I saw it on someone's website. The problem is a poorly
designed ground and this modification resolves it. A little searching on the
web and I am confident you will find it. I am limited to iPad now so I'll
leave that up to you. 
> 
> Sent from my iPad
> 
>>
On Mar 7, 2014, at 9:08 AM, Eddy Swynar <deswynar at xplornet.ca> wrote:

>> 
>>> On 2014-03-07, at 9:52 AM, WQ9E at btsnetworks.net wrote: Jim,
Eddy correctly identified the problem. It is from RF entering the VFO on 40M
where it is operating on the same frequency as the final. This problem is
even more common with the higher power Valiant although my even higher power
Viking 500 shows no sign of this problem and I have never heard of anyone
having it with the 500. In really severe cases it will also cause some FM
when operating AM. The only instance where I had to go beyond tightening all
of the VFO mounting screws properly (surface oxidation causes poor contact
with age) was in an early Valiant which had a long factory slot cut into the
case where the VFO shaft enters. I had to add some metallic shielding tape
to this one and it cured the problem. I expect the problem doesn't show up
on 160 since it takes a bigger "leak" in the shielding to let this lower
frequency radiation into the VFO. It can be successfully cured, I have a
Ranger 1, Ranger 2, Valiant 1, Valiant 2, Viking 500, Navigator, and
Pacemaker and none chirp on 40 CW. Rodger WQ9E
>> Hi Jim & Roger, In my case all it took to
fix the problem was a re-tightening of all of the VFO enclosure
screws---yes, the solution to such a vexing issue really & truly was just
that simple! ~73~ de Eddy VE3CUI -VE3XZ
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