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president grant mobile

samsonone1

Member
May 13, 2016
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My grant the volume drop's down but I can key the mike it comes back up then drop's back down in a few second's key the mike back up. anybody have any idea what the problem would be. The volume doesn't drop completely out just down.
 

Welcome to the forum Samsonone1!

Silly question, but have you turned the squelch all the way off, and "RF Gain" all the way up? I gotta ask.

Because of the age of this radio, it is possible you may have (electrolytic) capacitors on the verge of failure.

Is this a Grant XL or the older style Grant?

Edit: I see you said it's a President Grant, in that case i'm leaning towards a capacitor issue.
I don't want to sound offensive but I'm not sure how much experience you have with radio, could be a settings issue or hardware failure. Also, (if you have another microphone) I recommend that you try another mic because sometimes a single wire will break connection and cause the receive audio to go out.

(My thinking here is b/c you mentioned when you pick up the mic to key/unkey you notice the audio change. There's a chance the connection is being made momentarily, if you wiggle the cord around at all where it connects to the radio, does the audio come back?)




Best Regards.
 
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Yup; sounds just like a cap ready to go completely belly up. This radio - IMO - is a fine unit and really worth the expense to recap. Don't have one of these in my collection, but I may yet find one too. You will really like it when its working 100%. Aligned one for a local op awhile back. If you don't know how to rebuild a radio; then send it to a reliable shop and let them do it.
 
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There are 2 versions that share the name "President Grant". The old "3 button" version, which has the D858 SSB chassis in it, or the "4 button" version, which has the MB8719 chassis. I think N8FGB is right on the money by saying it's the relay. I suspect it's the D858 chassis, which uses a relay. Chances are the relay is excessively dirty and the contacts need to be cleaned.

~Cheers~
 
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Found a link here, to help explain what model you have w/pics.
Does your radio have four buttons, or just three in a row?

Yes, I would look at the relay first as n8fgb, & ExitThirteen have pointed out the old-school Grant had a tx/rx relay. I didn't think about this with the (Uniden) radio in mind, one day I'll have an old school President radio! If your radio uses a relay (what the problem sounds like now) the contacts may need to be cleaned. [Echo'ing n8fgb, Exit13]
 
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radio is just like the one in the video. it's a 4 button, an yes I have changed the mike with a brand new one. I have had this radio since the early 70's so I think I know how to operate the unit.
 
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what PLL is in the radio? since you have had it that long you should know what PLL is in it. would help with any questions you have to get a good answer. this is why so many are asking you what radio it is.
 
radio is just like the one in the video. it's a 4 button, an yes I have changed the mike with a brand new one. I have had this radio since the early 70's so I think I know how to operate the unit.
In that case, it's time for a total restoration.
Or servicing at least.

what PLL is in the radio? since you have had it that long you should know what PLL is in it. would help with any questions you have to get a good answer. this is why so many are asking you what radio it is.
He may not be into the technical aspect of radio but just enjoys using them.
I know a lot of people like that, but I can't speak for
Samsonone1.

If you have any interest in fixing or restoring this yourself, plenty of people on the forum will be able to share advice, opinions, or help you get going.

If you just need to send it out for a repair, & re-cap, somebody can point you to a recent thread discussing "mail-in repair service" as they can be hard to find locally.

Also as far I know, ExitThirteen & a few others on here can do mail-in service for some forum members. (PayPal or how ever done outside of the forum not through it) Best to PM an older forum member for advice on this, as i'm not trying to advertise or anything or break any forum rules. [I'd have to double check on the rules, but I don't see anything wrong with meeting a good tech on a (public) internet forum]

Best Regards
-Leap
 
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the radio has a mb8719 board like I said it is a 4 button model. Thank's
Right on, I always liked that PLL.

Also you can always "edit" the previous post instead of replying again.
Seems like you "double posted"
It's not a big deal but a simple edit (or deletion of the double post) helps to keep the forum less cluttered.
You get a 24 hour period to edit & correct any typos, or to add information if you need for the sake of the thread. :)

{tiny 'edit' button, should be under the post (y)}


Taken from the link posted earlier.
Now this is a President Grant from the transitional period of Uniden. It housed a board that had electronic switching for the TX and RX. It also had a 192 channel capable MB8719 PLL. What we cant see is the mic jack, instead of 4 pin, this radio had a 5 pin mic jack. The obvious sign that it is a Uniden made radio is the 4 push buttons on the front.

May be a bad cap, I guess you have no relay to try and clean!
If you take the lids off, do you see any relay?
 
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since the volume drops off and then you can key the mic it comes back. 1st thing I would do is pull the covers and press on the board with a pencil or a plastic tool and try this in different areas and see if the audio comes back with pushing on the board. you could have a bad solder joint which can cause this problem. if you do not find any area that the audio comes back by pushing on it. touch up the solder joints in the PLL, vco, and audio iC area. this may find the bad solder. be sure you have the radio off to touch up solder joints. leave it on while pushing on the board with a non metalic tool. you do not want to short some thing out.
 

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