Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Dec Fri 14, 2018 2:20 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 4 posts ] 
Author Message
 Post subject: Assistance requested on a modified CR88
PostPosted: Feb Fri 23, 2018 7:08 pm 
New Member

Joined: Feb Fri 23, 2018 6:48 pm
Posts: 2
Greetings from a newcomer:

Looking for information (have the manual) that would cover modifications to a CR88 I am restoring for a friend.
One of the modifications was to remove C75 and install a BNC female connector in its' place.
There have been several other undocumented changes that I will need to resolve.
There is white thread locking material on all the inductors (IF transformers). Was this standard procedure when the RCAF performed alignment or was this "third party".

I have worked on a couple of these very fine receivers in the past but none were in this otherwise very clean condition.

Broadcast band works fine. All others are relatively deaf.

I am very well equipped, test equipment wise.

TIA

Dave, W5WP


Top
 Profile  
 
 Post subject: Re: Assistance requested on a modified CR88
PostPosted: Feb Sat 24, 2018 2:41 pm 
Member

Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1180
Location: Santa Rosa, CA
Welcome to the group Dave!

My CR91 had been badly hacked as well and never did get it working
up to its potential. Most of the mods were done by another company
so it could be used in a diversity setup. Chances are the external BNC
was used to allow the use of an external VFO or BFO.
Mine had a switch added to turn these off.
Steve W6SSP

_________________
'cell phones and the internet are tools, not a lifestyle'


Top
 Profile  
 
 Post subject: Re: Assistance requested on a modified CR88
PostPosted: Feb Sat 24, 2018 7:35 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 3131
Location: Seattle WA US
Dave-
C75 is the phasing control for the crystal filter. If it is missing, you should check and see if the crystal is also missing......
Since neither end of C75 is grounded, you need to explore in more detail where the center pin of the new BNC connector is conneccted.
If the crystal filter has been removed, signals may reach the first IF only if wider IF bandwidths have been selected.

-Chuck K7MCG


Top
 Profile  
 
 Post subject: Re: Assistance requested on a modified CR88
PostPosted: Feb Sun 25, 2018 1:43 am 
New Member

Joined: Feb Fri 23, 2018 6:48 pm
Posts: 2
Chuck;

Thanks for the reply.

The BNC connector goes to pin 5 (cathode) of V5, the first IF. Scope and VOM show DC which indicates slight variation to changes in signal strength as if someone was attempting to obtain a connection point for an outboard "S" meter. Level is dependent on the settings of both RF gain and IF gain controls. The phasing crystal (marked 455) is present.

Dave, W5WP


Top
 Profile  
 
Post New Topic Post Reply  [ 4 posts ]  Moderator: Sandy

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 6 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB